DocumentClient.cs

//------------------------------------------------------------
// Copyright (c) Microsoft Corporation.  All rights reserved.
//------------------------------------------------------------

namespace Microsoft.Azure.Cosmos
{
    using System;
    using System.Collections.Generic;
    using System.Diagnostics;
    using System.Globalization;
    using System.IO;
    using System.Linq;
    using System.Net;
    using System.Net.Http;
    using System.Net.Security;
    using System.Security;
    using System.Text;
    using System.Threading;
    using System.Threading.Tasks;
    using global::Azure.Core;
    using Microsoft.Azure.Cosmos.Common;
    using Microsoft.Azure.Cosmos.Core.Trace;
    using Microsoft.Azure.Cosmos.Handler;
    using Microsoft.Azure.Cosmos.Query;
    using Microsoft.Azure.Cosmos.Query.Core.QueryPlan;
    using Microsoft.Azure.Cosmos.Routing;
    using Microsoft.Azure.Cosmos.Telemetry;
    using Microsoft.Azure.Cosmos.Tracing;
    using Microsoft.Azure.Cosmos.Tracing.TraceData;
    using Microsoft.Azure.Documents;
    using Microsoft.Azure.Documents.Client;
    using Microsoft.Azure.Documents.Collections;
    using Microsoft.Azure.Documents.Routing;
    using Newtonsoft.Json;

    /// <summary>
    /// Provides a client-side logical representation for the Azure Cosmos DB service.
    /// This client is used to configure and execute requests against the service.
    /// </summary>
    /// <threadSafety>
    /// This type is thread safe.
    /// </threadSafety>
    /// <remarks>
    /// The service client that encapsulates the endpoint and credentials and connection policy used to access the Azure Cosmos DB service.
    /// It is recommended to cache and reuse this instance within your application rather than creating a new instance for every operation.
    ///
    /// <para>
    /// When your app uses DocumentClient, you should call its IDisposable.Dispose implementation when you are finished using it.
    /// Depending on your programming technique, you can do this in one of two ways:
    /// </para>
    ///
    /// <para>
    /// 1. By using a language construct such as the using statement in C#.
    /// The using statement is actually a syntactic convenience.
    /// At compile time, the language compiler implements the intermediate language (IL) for a try/catch block.
    /// <code language="c#">
    /// <![CDATA[
    /// using (IDocumentClient client = new DocumentClient(new Uri("endpoint"), "authKey"))
    /// {
    ///     ...
    /// }
    /// ]]>
    /// </code>
    /// </para>
    ///
    /// <para>
    /// 2. By wrapping the call to the IDisposable.Dispose implementation in a try/catch block.
    /// The following example replaces the using block in the previous example with a try/catch/finally block.
    /// <code language="c#">
    /// <![CDATA[
    /// IDocumentClient client = new DocumentClient(new Uri("endpoint"), "authKey"))
    /// try{
    ///     ...
    /// }
    /// finally{
    ///     if (client != null) client.Dispose();
    /// }
    /// ]]>
    /// </code>
    /// </para>
    ///
    /// </remarks>
    internal partial class DocumentClient : IDisposable, IAuthorizationTokenProvider, ICosmosAuthorizationTokenProvider, IDocumentClient, IDocumentClientInternal
    {
        private const string AllowOverrideStrongerConsistency = "AllowOverrideStrongerConsistency";
        private const string MaxConcurrentConnectionOpenConfig = "MaxConcurrentConnectionOpenRequests";
        private const string IdleConnectionTimeoutInSecondsConfig = "IdleConnectionTimeoutInSecondsConfig";
        private const string OpenConnectionTimeoutInSecondsConfig = "OpenConnectionTimeoutInSecondsConfig";
        private const string TransportTimerPoolGranularityInSecondsConfig = "TransportTimerPoolGranularityInSecondsConfig";
        private const string EnableTcpChannelConfig = "CosmosDbEnableTcpChannel";
        private const string MaxRequestsPerChannelConfig = "CosmosDbMaxRequestsPerTcpChannel";
        private const string TcpPartitionCount = "CosmosDbTcpPartitionCount";
        private const string MaxChannelsPerHostConfig = "CosmosDbMaxTcpChannelsPerHost";
        private const string RntbdPortReuseMode = "CosmosDbTcpPortReusePolicy";
        private const string RntbdPortPoolReuseThreshold = "CosmosDbTcpPortReuseThreshold";
        private const string RntbdPortPoolBindAttempts = "CosmosDbTcpPortReuseBindAttempts";
        private const string RntbdReceiveHangDetectionTimeConfig = "CosmosDbTcpReceiveHangDetectionTimeSeconds";
        private const string RntbdSendHangDetectionTimeConfig = "CosmosDbTcpSendHangDetectionTimeSeconds";
        private const string EnableCpuMonitorConfig = "CosmosDbEnableCpuMonitor";
        // Env variable
        private const string RntbdMaxConcurrentOpeningConnectionCountConfig = "AZURE_COSMOS_TCP_MAX_CONCURRENT_OPENING_CONNECTION_COUNT";

        private const int MaxConcurrentConnectionOpenRequestsPerProcessor = 25;
        private const int DefaultMaxRequestsPerRntbdChannel = 30;
        private const int DefaultRntbdPartitionCount = 1;
        private const int DefaultMaxRntbdChannelsPerHost = ushort.MaxValue;
        private const PortReuseMode DefaultRntbdPortReuseMode = PortReuseMode.ReuseUnicastPort;
        private const int DefaultRntbdPortPoolReuseThreshold = 256;
        private const int DefaultRntbdPortPoolBindAttempts = 5;
        private const int DefaultRntbdReceiveHangDetectionTimeSeconds = 65;
        private const int DefaultRntbdSendHangDetectionTimeSeconds = 10;
        private const bool DefaultEnableCpuMonitor = true;
        private const string DefaultInitTaskKey = "InitTaskKey";

        private readonly bool IsLocalQuorumConsistency = false;
        private readonly bool isReplicaAddressValidationEnabled;

        //Auth
        internal readonly AuthorizationTokenProvider cosmosAuthorization;

        // Gateway has backoff/retry logic to hide transient errors.
        private RetryPolicy retryPolicy;
        private bool allowOverrideStrongerConsistency = false;
        private int maxConcurrentConnectionOpenRequests = Environment.ProcessorCount * MaxConcurrentConnectionOpenRequestsPerProcessor;
        private int openConnectionTimeoutInSeconds = 5;
        private int idleConnectionTimeoutInSeconds = -1;
        private int timerPoolGranularityInSeconds = 1;
        private bool enableRntbdChannel = true;
        private int maxRequestsPerRntbdChannel = DefaultMaxRequestsPerRntbdChannel;
        private int rntbdPartitionCount = DefaultRntbdPartitionCount;
        private int maxRntbdChannels = DefaultMaxRntbdChannelsPerHost;
        private PortReuseMode rntbdPortReuseMode = DefaultRntbdPortReuseMode;
        private int rntbdPortPoolReuseThreshold = DefaultRntbdPortPoolReuseThreshold;
        private int rntbdPortPoolBindAttempts = DefaultRntbdPortPoolBindAttempts;
        private int rntbdReceiveHangDetectionTimeSeconds = DefaultRntbdReceiveHangDetectionTimeSeconds;
        private int rntbdSendHangDetectionTimeSeconds = DefaultRntbdSendHangDetectionTimeSeconds;
        private bool enableCpuMonitor = DefaultEnableCpuMonitor;
        private int rntbdMaxConcurrentOpeningConnectionCount = 5;
        private string clientId;

        //Consistency
        private Documents.ConsistencyLevel? desiredConsistencyLevel;

        internal CosmosAccountServiceConfiguration accountServiceConfiguration { get; private set; }
        internal ClientTelemetry clientTelemetry { get; set; }

        private ClientCollectionCache collectionCache;

        private PartitionKeyRangeCache partitionKeyRangeCache;

        //Private state.
        private bool isSuccessfullyInitialized;
        private bool isDisposed;

        // creator of TransportClient is responsible for disposing it.
        private IStoreClientFactory storeClientFactory;
        internal CosmosHttpClient httpClient { get; private set; }

        // Flag that indicates whether store client factory must be disposed whenever client is disposed.
        // Setting this flag to false will result in store client factory not being disposed when client is disposed.
        // This flag is used to allow shared store client factory survive disposition of a document client while other clients continue using it.
        private bool isStoreClientFactoryCreatedInternally;

        //Id counter.
        private static int idCounter;
        //Trace Id.
        private int traceId;

        //RemoteCertificateValidationCallback
        internal RemoteCertificateValidationCallback remoteCertificateValidationCallback;

        //Distributed Tracing Flag
        internal bool isDistributedTracingEnabled;

        //SessionContainer.
        internal ISessionContainer sessionContainer;

        private readonly CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();

        private AsyncLazy<QueryPartitionProvider> queryPartitionProvider;

        private DocumentClientEventSource eventSource;
        private Func<bool, Task<bool>> initializeTaskFactory;
        internal AsyncCacheNonBlocking<string, bool> initTaskCache;

        private JsonSerializerSettings serializerSettings;
        private event EventHandler<SendingRequestEventArgs> sendingRequest;
        private event EventHandler<ReceivedResponseEventArgs> receivedResponse;
        private Func<TransportClient, TransportClient> transportClientHandlerFactory;

        /// <summary>
        /// Initializes a new instance of the <see cref="DocumentClient"/> class using the
        /// specified Azure Cosmos DB service endpoint, key, and connection policy for the Azure Cosmos DB service.
        /// </summary>
        /// <param name="serviceEndpoint">
        /// The service endpoint to use to create the client.
        /// </param>
        /// <param name="authKey">
        /// The list of Permission objects to use to create the client.
        /// </param>
        /// <param name="connectionPolicy">
        /// (Optional) The connection policy for the client. If none is passed, the default is used <see cref="ConnectionPolicy"/>
        /// </param>
        /// <param name="desiredConsistencyLevel">
        /// (Optional) This can be used to weaken the database account consistency level for read operations.
        /// If this is not set the database account consistency level will be used for all requests.
        /// </param>
        /// <remarks>
        /// The service endpoint and the authorization key can be obtained from the Azure Management Portal.
        /// The authKey used here is encrypted for privacy when being used, and deleted from computer memory when no longer needed
        /// <para>
        /// Using Direct connectivity, wherever possible, is recommended
        /// </para>
        /// </remarks>
        /// <seealso cref="Uri"/>
        /// <seealso cref="SecureString"/>
        /// <seealso cref="ConnectionPolicy"/>
        /// <seealso cref="ConsistencyLevel"/>
        public DocumentClient(Uri serviceEndpoint,
                              SecureString authKey,
                              ConnectionPolicy connectionPolicy = null,
                              Documents.ConsistencyLevel? desiredConsistencyLevel = null)
        {
            if (authKey == null)
            {
                throw new ArgumentNullException("authKey");
            }

            if (authKey != null)
            {
                this.cosmosAuthorization = new AuthorizationTokenProviderMasterKey(authKey);
            }

            this.Initialize(serviceEndpoint, connectionPolicy, desiredConsistencyLevel);
            this.initTaskCache = new AsyncCacheNonBlocking<string, bool>(cancellationToken: this.cancellationTokenSource.Token);
            this.isReplicaAddressValidationEnabled = ConfigurationManager.IsReplicaAddressValidationEnabled();
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="DocumentClient"/> class using the
        /// specified Azure Cosmos DB service endpoint, key, connection policy and a custom JsonSerializerSettings
        /// for the Azure Cosmos DB service.
        /// </summary>
        /// <param name="serviceEndpoint">
        /// The service endpoint to use to create the client.
        /// </param>
        /// <param name="authKey">
        /// The list of Permission objects to use to create the client.
        /// </param>
        /// <param name="connectionPolicy">
        /// The connection policy for the client.
        /// </param>
        /// <param name="desiredConsistencyLevel">
        /// This can be used to weaken the database account consistency level for read operations.
        /// If this is not set the database account consistency level will be used for all requests.
        /// </param>
        /// <param name="serializerSettings">
        /// The custom JsonSerializer settings to be used for serialization/derialization.
        /// </param>
        /// <remarks>
        /// The service endpoint and the authorization key can be obtained from the Azure Management Portal.
        /// The authKey used here is encrypted for privacy when being used, and deleted from computer memory when no longer needed
        /// <para>
        /// Using Direct connectivity, wherever possible, is recommended
        /// </para>
        /// </remarks>
        /// <seealso cref="Uri"/>
        /// <seealso cref="SecureString"/>
        /// <seealso cref="ConnectionPolicy"/>
        /// <seealso cref="ConsistencyLevel"/>
        /// <seealso cref="JsonSerializerSettings"/>
        [Obsolete("Please use the constructor that takes JsonSerializerSettings as the third parameter.")]
        public DocumentClient(Uri serviceEndpoint,
                              SecureString authKey,
                              ConnectionPolicy connectionPolicy,
                              Documents.ConsistencyLevel? desiredConsistencyLevel,
                              JsonSerializerSettings serializerSettings)
            : this(serviceEndpoint, authKey, connectionPolicy, desiredConsistencyLevel)
        {
            this.serializerSettings = serializerSettings;
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="DocumentClient"/> class using the
        /// specified Azure Cosmos DB service endpoint, key, connection policy and a custom JsonSerializerSettings
        /// for the Azure Cosmos DB service.
        /// </summary>
        /// <param name="serviceEndpoint">
        /// The service endpoint to use to create the client.
        /// </param>
        /// <param name="authKey">
        /// The list of Permission objects to use to create the client.
        /// </param>
        /// <param name="serializerSettings">
        /// The custom JsonSerializer settings to be used for serialization/derialization.
        /// </param>
        /// <param name="connectionPolicy">
        /// (Optional) The connection policy for the client. If none is passed, the default is used <see cref="ConnectionPolicy"/>
        /// </param>
        /// <param name="desiredConsistencyLevel">
        /// (Optional) This can be used to weaken the database account consistency level for read operations.
        /// If this is not set the database account consistency level will be used for all requests.
        /// </param>
        /// <remarks>
        /// The service endpoint and the authorization key can be obtained from the Azure Management Portal.
        /// The authKey used here is encrypted for privacy when being used, and deleted from computer memory when no longer needed
        /// <para>
        /// Using Direct connectivity, wherever possible, is recommended
        /// </para>
        /// </remarks>
        /// <seealso cref="Uri"/>
        /// <seealso cref="SecureString"/>
        /// <seealso cref="JsonSerializerSettings"/>
        /// <seealso cref="ConnectionPolicy"/>
        /// <seealso cref="ConsistencyLevel"/>
        public DocumentClient(Uri serviceEndpoint,
                              SecureString authKey,
                              JsonSerializerSettings serializerSettings,
                              ConnectionPolicy connectionPolicy = null,
                              Documents.ConsistencyLevel? desiredConsistencyLevel = null)
            : this(serviceEndpoint, authKey, connectionPolicy, desiredConsistencyLevel)
        {
            this.serializerSettings = serializerSettings;
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="DocumentClient"/> class using the
        /// specified service endpoint, an authorization key (or resource token) and a connection policy
        /// for the Azure Cosmos DB service.
        /// </summary>
        /// <param name="serviceEndpoint">The service endpoint to use to create the client.</param>
        /// <param name="authKeyOrResourceToken">The authorization key or resource token to use to create the client.</param>
        /// <param name="connectionPolicy">(Optional) The connection policy for the client.</param>
        /// <param name="desiredConsistencyLevel">(Optional) The default consistency policy for client operations.</param>
        /// <remarks>
        /// The service endpoint can be obtained from the Azure Management Portal.
        /// If you are connecting using one of the Master Keys, these can be obtained along with the endpoint from the Azure Management Portal
        /// If however you are connecting as a specific Azure Cosmos DB User, the value passed to <paramref name="authKeyOrResourceToken"/> is the ResourceToken obtained from the permission feed for the user.
        /// <para>
        /// Using Direct connectivity, wherever possible, is recommended.
        /// </para>
        /// </remarks>
        /// <seealso cref="Uri"/>
        /// <seealso cref="ConnectionPolicy"/>
        /// <seealso cref="ConsistencyLevel"/>
        public DocumentClient(Uri serviceEndpoint,
                              string authKeyOrResourceToken,
                              ConnectionPolicy connectionPolicy = null,
                              Documents.ConsistencyLevel? desiredConsistencyLevel = null)
            : this(serviceEndpoint, authKeyOrResourceToken, sendingRequestEventArgs: null, connectionPolicy: connectionPolicy, desiredConsistencyLevel: desiredConsistencyLevel)
        {
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="DocumentClient"/> class using the
        /// specified service endpoint, an authorization key (or resource token) and a connection policy
        /// for the Azure Cosmos DB service.
        /// </summary>
        /// <param name="serviceEndpoint">The service endpoint to use to create the client.</param>
        /// <param name="authKeyOrResourceToken">The authorization key or resource token to use to create the client.</param>
        /// <param name="handler">The HTTP handler stack to use for sending requests (e.g., HttpClientHandler).</param>
        /// <param name="connectionPolicy">(Optional) The connection policy for the client.</param>
        /// <param name="desiredConsistencyLevel">(Optional) The default consistency policy for client operations.</param>
        /// <remarks>
        /// The service endpoint can be obtained from the Azure Management Portal.
        /// If you are connecting using one of the Master Keys, these can be obtained along with the endpoint from the Azure Management Portal
        /// If however you are connecting as a specific Azure Cosmos DB User, the value passed to <paramref name="authKeyOrResourceToken"/> is the ResourceToken obtained from the permission feed for the user.
        /// <para>
        /// Using Direct connectivity, wherever possible, is recommended.
        /// </para>
        /// </remarks>
        /// <seealso cref="Uri"/>
        /// <seealso cref="ConnectionPolicy"/>
        /// <seealso cref="ConsistencyLevel"/>
        public DocumentClient(Uri serviceEndpoint,
                              string authKeyOrResourceToken,
                              HttpMessageHandler handler,
                              ConnectionPolicy connectionPolicy = null,
                              Documents.ConsistencyLevel? desiredConsistencyLevel = null)
            : this(serviceEndpoint, authKeyOrResourceToken, sendingRequestEventArgs: null, connectionPolicy: connectionPolicy, desiredConsistencyLevel: desiredConsistencyLevel, handler: handler)
        {
        }

        internal DocumentClient(Uri serviceEndpoint,
                      string authKeyOrResourceToken,
                      EventHandler<SendingRequestEventArgs> sendingRequestEventArgs,
                      ConnectionPolicy connectionPolicy = null,
                      Documents.ConsistencyLevel? desiredConsistencyLevel = null,
                      JsonSerializerSettings serializerSettings = null,
                      ApiType apitype = ApiType.None,
                      EventHandler<ReceivedResponseEventArgs> receivedResponseEventArgs = null,
                      HttpMessageHandler handler = null,
                      ISessionContainer sessionContainer = null,
                      bool? enableCpuMonitor = null,
                      Func<TransportClient, TransportClient> transportClientHandlerFactory = null,
                      IStoreClientFactory storeClientFactory = null)
            : this(serviceEndpoint,
                AuthorizationTokenProvider.CreateWithResourceTokenOrAuthKey(authKeyOrResourceToken),
                sendingRequestEventArgs,
                connectionPolicy,
                desiredConsistencyLevel,
                serializerSettings,
                apitype,
                receivedResponseEventArgs,
                handler,
                sessionContainer,
                enableCpuMonitor,
                transportClientHandlerFactory,
                storeClientFactory)
        {
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="DocumentClient"/> class using the
        /// specified service endpoint, an authorization key (or resource token) and a connection policy
        /// for the Azure Cosmos DB service.
        /// </summary>
        /// <param name="serviceEndpoint">The service endpoint to use to create the client.</param>
        /// <param name="cosmosAuthorization">The cosmos authorization for the client.</param>
        /// <param name="sendingRequestEventArgs"> The event handler to be invoked before the request is sent.</param>
        /// <param name="receivedResponseEventArgs"> The event handler to be invoked after a response has been received.</param>
        /// <param name="connectionPolicy">(Optional) The connection policy for the client.</param>
        /// <param name="desiredConsistencyLevel">(Optional) The default consistency policy for client operations.</param>
        /// <param name="serializerSettings">The custom JsonSerializer settings to be used for serialization/derialization.</param>
        /// <param name="apitype">Api type for the account</param>
        /// <param name="handler">The HTTP handler stack to use for sending requests (e.g., HttpClientHandler).</param>
        /// <param name="sessionContainer">The default session container with which DocumentClient is created.</param>
        /// <param name="enableCpuMonitor">Flag that indicates whether client-side CPU monitoring is enabled for improved troubleshooting.</param>
        /// <param name="transportClientHandlerFactory">Transport client handler factory.</param>
        /// <param name="storeClientFactory">Factory that creates store clients sharing the same transport client to optimize network resource reuse across multiple document clients in the same process.</param>
        /// <param name="isLocalQuorumConsistency">Flag to allow Quorum Read with Eventual Consistency Account</param>
        /// <param name="cosmosClientId"></param>
        /// <param name="remoteCertificateValidationCallback">This delegate responsible for validating the third party certificate. </param>
        /// <param name="isDistributedTracingEnabled">This is distributed tracing flag</param>
        /// <remarks>
        /// The service endpoint can be obtained from the Azure Management Portal.
        /// If you are connecting using one of the Master Keys, these can be obtained along with the endpoint from the Azure Management Portal
        /// If however you are connecting as a specific Azure Cosmos DB User, the value passed to is the ResourceToken obtained from the permission feed for the user.
        /// <para>
        /// Using Direct connectivity, wherever possible, is recommended.
        /// </para>
        /// </remarks>
        /// <seealso cref="Uri"/>
        /// <seealso cref="ConnectionPolicy"/>
        /// <seealso cref="ConsistencyLevel"/>
        internal DocumentClient(Uri serviceEndpoint,
                              AuthorizationTokenProvider cosmosAuthorization,
                              EventHandler<SendingRequestEventArgs> sendingRequestEventArgs,
                              ConnectionPolicy connectionPolicy = null,
                              Documents.ConsistencyLevel? desiredConsistencyLevel = null,
                              JsonSerializerSettings serializerSettings = null,
                              ApiType apitype = ApiType.None,
                              EventHandler<ReceivedResponseEventArgs> receivedResponseEventArgs = null,
                              HttpMessageHandler handler = null,
                              ISessionContainer sessionContainer = null,
                              bool? enableCpuMonitor = null,
                              Func<TransportClient, TransportClient> transportClientHandlerFactory = null,
                              IStoreClientFactory storeClientFactory = null,
                              bool isLocalQuorumConsistency = false,
                              string cosmosClientId = null,
                              RemoteCertificateValidationCallback remoteCertificateValidationCallback = null,
                              bool isDistributedTracingEnabled = false)
        {
            if (sendingRequestEventArgs != null)
            {
                this.sendingRequest += sendingRequestEventArgs;
            }

            if (serializerSettings != null)
            {
                this.serializerSettings = serializerSettings;
            }

            this.ApiType = apitype;

            if (receivedResponseEventArgs != null)
            {
                this.receivedResponse += receivedResponseEventArgs;
            }

            this.cosmosAuthorization = cosmosAuthorization ?? throw new ArgumentNullException(nameof(cosmosAuthorization));
            this.transportClientHandlerFactory = transportClientHandlerFactory;
            this.IsLocalQuorumConsistency = isLocalQuorumConsistency;
            this.initTaskCache = new AsyncCacheNonBlocking<string, bool>(cancellationToken: this.cancellationTokenSource.Token);

            this.Initialize(
                serviceEndpoint: serviceEndpoint,
                connectionPolicy: connectionPolicy,
                desiredConsistencyLevel: desiredConsistencyLevel,
                handler: handler,
                sessionContainer: sessionContainer,
                enableCpuMonitor: enableCpuMonitor,
                storeClientFactory: storeClientFactory,
                cosmosClientId: cosmosClientId,
                remoteCertificateValidationCallback: remoteCertificateValidationCallback,
                isDistributedTracingEnabled: isDistributedTracingEnabled);
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="DocumentClient"/> class using the
        /// specified service endpoint, an authorization key (or resource token), a connection policy
        /// and a custom JsonSerializerSettings for the Azure Cosmos DB service.
        /// </summary>
        /// <param name="serviceEndpoint">The service endpoint to use to create the client.</param>
        /// <param name="authKeyOrResourceToken">The authorization key or resource token to use to create the client.</param>
        /// <param name="connectionPolicy">The connection policy for the client.</param>
        /// <param name="desiredConsistencyLevel">The default consistency policy for client operations.</param>
        /// <param name="serializerSettings">The custom JsonSerializer settings to be used for serialization/derialization.</param>
        /// <remarks>
        /// The service endpoint can be obtained from the Azure Management Portal.
        /// If you are connecting using one of the Master Keys, these can be obtained along with the endpoint from the Azure Management Portal
        /// If however you are connecting as a specific Azure Cosmos DB User, the value passed to <paramref name="authKeyOrResourceToken"/> is the ResourceToken obtained from the permission feed for the user.
        /// <para>
        /// Using Direct connectivity, wherever possible, is recommended.
        /// </para>
        /// </remarks>
        /// <seealso cref="Uri"/>
        /// <seealso cref="ConnectionPolicy"/>
        /// <seealso cref="ConsistencyLevel"/>
        /// <seealso cref="JsonSerializerSettings"/>
        [Obsolete("Please use the constructor that takes JsonSerializerSettings as the third parameter.")]
        public DocumentClient(Uri serviceEndpoint,
                              string authKeyOrResourceToken,
                              ConnectionPolicy connectionPolicy,
                              Documents.ConsistencyLevel? desiredConsistencyLevel,
                              JsonSerializerSettings serializerSettings)
            : this(serviceEndpoint, authKeyOrResourceToken, (HttpMessageHandler)null, connectionPolicy, desiredConsistencyLevel)
        {
            this.serializerSettings = serializerSettings;
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="DocumentClient"/> class using the
        /// specified service endpoint, an authorization key (or resource token), a connection policy
        /// and a custom JsonSerializerSettings for the Azure Cosmos DB service.
        /// </summary>
        /// <param name="serviceEndpoint">The service endpoint to use to create the client.</param>
        /// <param name="authKeyOrResourceToken">The authorization key or resource token to use to create the client.</param>
        /// <param name="serializerSettings">The custom JsonSerializer settings to be used for serialization/derialization.</param>
        /// <param name="connectionPolicy">(Optional) The connection policy for the client.</param>
        /// <param name="desiredConsistencyLevel">(Optional) The default consistency policy for client operations.</param>
        /// <remarks>
        /// The service endpoint can be obtained from the Azure Management Portal.
        /// If you are connecting using one of the Master Keys, these can be obtained along with the endpoint from the Azure Management Portal
        /// If however you are connecting as a specific Azure Cosmos DB User, the value passed to <paramref name="authKeyOrResourceToken"/> is the ResourceToken obtained from the permission feed for the user.
        /// <para>
        /// Using Direct connectivity, wherever possible, is recommended.
        /// </para>
        /// </remarks>
        /// <seealso cref="Uri"/>
        /// <seealso cref="JsonSerializerSettings"/>
        /// <seealso cref="ConnectionPolicy"/>
        /// <seealso cref="ConsistencyLevel"/>
        public DocumentClient(Uri serviceEndpoint,
                              string authKeyOrResourceToken,
                              JsonSerializerSettings serializerSettings,
                              ConnectionPolicy connectionPolicy = null,
                              Documents.ConsistencyLevel? desiredConsistencyLevel = null)
            : this(serviceEndpoint, authKeyOrResourceToken, (HttpMessageHandler)null, connectionPolicy, desiredConsistencyLevel)
        {
            this.serializerSettings = serializerSettings;
        }

        /// <summary>
        /// Internal constructor purely for unit-testing
        /// </summary>
        internal DocumentClient(Uri serviceEndpoint, string authKey)
        {
            // do nothing 
            this.ServiceEndpoint = serviceEndpoint;
            this.ConnectionPolicy = new ConnectionPolicy();
        }

        internal virtual async Task<ClientCollectionCache> GetCollectionCacheAsync(ITrace trace)
        {
            using (ITrace childTrace = trace.StartChild("Get Collection Cache", TraceComponent.Routing, Tracing.TraceLevel.Info))
            {
                await this.EnsureValidClientAsync(childTrace);
                return this.collectionCache;
            }
        }

        internal virtual async Task<PartitionKeyRangeCache> GetPartitionKeyRangeCacheAsync(ITrace trace)
        {
            using (ITrace childTrace = trace.StartChild("Get Partition Key Range Cache", TraceComponent.Routing, Tracing.TraceLevel.Info))
            {
                await this.EnsureValidClientAsync(childTrace);
                return this.partitionKeyRangeCache;
            }
        }

        internal GlobalAddressResolver AddressResolver { get; private set; }

        internal GlobalEndpointManager GlobalEndpointManager { get; private set; }
        
        internal GlobalPartitionEndpointManager PartitionKeyRangeLocation { get; private set; }

        /// <summary>
        /// Open the connection to validate that the client initialization is successful in the Azure Cosmos DB service.
        /// </summary>
        /// <returns>
        /// A <see cref="System.Threading.Tasks.Task"/> object.
        /// </returns>
        /// <remarks>
        /// This method is recommended to be called, after the constructor, but before calling any other methods on the DocumentClient instance.
        /// If there are any initialization exceptions, this method will throw them (set on the task).
        /// Alternately, calling any API will throw initialization exception at the first call.
        /// </remarks>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// using (IDocumentClient client = new DocumentClient(new Uri("service endpoint"), "auth key"))
        /// {
        ///     await client.OpenAsync();
        /// }
        /// ]]>
        /// </code>
        /// </example>
        public Task OpenAsync(CancellationToken cancellationToken = default)
        {
            return TaskHelper.InlineIfPossibleAsync(() => this.OpenPrivateInlineAsync(cancellationToken), null, cancellationToken);
        }

        private async Task OpenPrivateInlineAsync(CancellationToken cancellationToken)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);
            await TaskHelper.InlineIfPossibleAsync(() => this.OpenPrivateAsync(cancellationToken), this.ResetSessionTokenRetryPolicy.GetRequestPolicy(), cancellationToken);
        }

        private async Task OpenPrivateAsync(CancellationToken cancellationToken)
        {
            // Initialize caches for all databases and collections
            ResourceFeedReader<Documents.Database> databaseFeedReader = this.CreateDatabaseFeedReader(
                new FeedOptions { MaxItemCount = -1 });

            try
            {
                while (databaseFeedReader.HasMoreResults)
                {
                    foreach (Documents.Database database in await databaseFeedReader.ExecuteNextAsync(cancellationToken))
                    {
                        ResourceFeedReader<DocumentCollection> collectionFeedReader = this.CreateDocumentCollectionFeedReader(
                            database.SelfLink,
                            new FeedOptions { MaxItemCount = -1 });
                        List<Task> tasks = new List<Task>();
                        while (collectionFeedReader.HasMoreResults)
                        {
                            tasks.AddRange((await collectionFeedReader.ExecuteNextAsync(cancellationToken)).Select(collection => this.InitializeCachesAsync(database.Id, collection, cancellationToken)));
                        }

                        await Task.WhenAll(tasks);
                    }
                }
            }
            catch (DocumentClientException ex)
            {
                // Clear the caches to ensure that we don't have partial results
                this.collectionCache = new ClientCollectionCache(
                    sessionContainer: this.sessionContainer, 
                    storeModel: this.GatewayStoreModel, 
                    tokenProvider: this, 
                    retryPolicy: this.retryPolicy,
                    clientTelemetry: this.clientTelemetry);
                this.partitionKeyRangeCache = new PartitionKeyRangeCache(this, this.GatewayStoreModel, this.collectionCache);

                DefaultTrace.TraceWarning("{0} occurred while OpenAsync. Exception Message: {1}", ex.ToString(), ex.Message);
            }
        }

        internal virtual void Initialize(Uri serviceEndpoint,
            ConnectionPolicy connectionPolicy = null,
            Documents.ConsistencyLevel? desiredConsistencyLevel = null,
            HttpMessageHandler handler = null,
            ISessionContainer sessionContainer = null,
            bool? enableCpuMonitor = null,
            IStoreClientFactory storeClientFactory = null,
            TokenCredential tokenCredential = null,
            string cosmosClientId = null,
            RemoteCertificateValidationCallback remoteCertificateValidationCallback = null,
            bool isDistributedTracingEnabled = false)
        {
            if (serviceEndpoint == null)
            {
                throw new ArgumentNullException("serviceEndpoint");
            }

            this.clientId = cosmosClientId;
            this.remoteCertificateValidationCallback = remoteCertificateValidationCallback;
            this.isDistributedTracingEnabled = isDistributedTracingEnabled;

            this.queryPartitionProvider = new AsyncLazy<QueryPartitionProvider>(async () =>
            {
                await this.EnsureValidClientAsync(NoOpTrace.Singleton);
                return new QueryPartitionProvider(this.accountServiceConfiguration.QueryEngineConfiguration);
            }, CancellationToken.None);

#if !(NETSTANDARD15 || NETSTANDARD16)
#if NETSTANDARD20
            // GetEntryAssembly returns null when loaded from native netstandard2.0
            if (System.Reflection.Assembly.GetEntryAssembly() != null)
            {
#endif
                // For tests we want to allow stronger consistency during construction or per call
                string allowOverrideStrongerConsistencyConfig = System.Configuration.ConfigurationManager.AppSettings[DocumentClient.AllowOverrideStrongerConsistency];
                if (!string.IsNullOrEmpty(allowOverrideStrongerConsistencyConfig))
                {
                    if (!bool.TryParse(allowOverrideStrongerConsistencyConfig, out this.allowOverrideStrongerConsistency))
                    {
                        this.allowOverrideStrongerConsistency = false;
                    }
                }

                // We might want to override the defaults sometime
                string maxConcurrentConnectionOpenRequestsOverrideString = System.Configuration.ConfigurationManager.AppSettings[DocumentClient.MaxConcurrentConnectionOpenConfig];
                if (!string.IsNullOrEmpty(maxConcurrentConnectionOpenRequestsOverrideString))
                {
                    int maxConcurrentConnectionOpenRequestOverrideInt = 0;
                    if (Int32.TryParse(maxConcurrentConnectionOpenRequestsOverrideString, out maxConcurrentConnectionOpenRequestOverrideInt))
                    {
                        this.maxConcurrentConnectionOpenRequests = maxConcurrentConnectionOpenRequestOverrideInt;
                    }
                }

                string openConnectionTimeoutInSecondsOverrideString = System.Configuration.ConfigurationManager.AppSettings[DocumentClient.OpenConnectionTimeoutInSecondsConfig];
                if (!string.IsNullOrEmpty(openConnectionTimeoutInSecondsOverrideString))
                {
                    int openConnectionTimeoutInSecondsOverrideInt = 0;
                    if (Int32.TryParse(openConnectionTimeoutInSecondsOverrideString, out openConnectionTimeoutInSecondsOverrideInt))
                    {
                        this.openConnectionTimeoutInSeconds = openConnectionTimeoutInSecondsOverrideInt;
                    }
                }

                string idleConnectionTimeoutInSecondsOverrideString = System.Configuration.ConfigurationManager.AppSettings[DocumentClient.IdleConnectionTimeoutInSecondsConfig];
                if (!string.IsNullOrEmpty(idleConnectionTimeoutInSecondsOverrideString))
                {
                    int idleConnectionTimeoutInSecondsOverrideInt = 0;
                    if (Int32.TryParse(idleConnectionTimeoutInSecondsOverrideString, out idleConnectionTimeoutInSecondsOverrideInt))
                    {
                        this.idleConnectionTimeoutInSeconds = idleConnectionTimeoutInSecondsOverrideInt;
                    }
                }

                string transportTimerPoolGranularityInSecondsOverrideString = System.Configuration.ConfigurationManager.AppSettings[DocumentClient.TransportTimerPoolGranularityInSecondsConfig];
                if (!string.IsNullOrEmpty(transportTimerPoolGranularityInSecondsOverrideString))
                {
                    int timerPoolGranularityInSecondsOverrideInt = 0;
                    if (Int32.TryParse(transportTimerPoolGranularityInSecondsOverrideString, out timerPoolGranularityInSecondsOverrideInt))
                    {
                        // timeoutgranularity specified should be greater than min(5 seconds)
                        if (timerPoolGranularityInSecondsOverrideInt > this.timerPoolGranularityInSeconds)
                        {
                            this.timerPoolGranularityInSeconds = timerPoolGranularityInSecondsOverrideInt;
                        }
                    }
                }

                string enableRntbdChannelOverrideString = System.Configuration.ConfigurationManager.AppSettings[DocumentClient.EnableTcpChannelConfig];
                if (!string.IsNullOrEmpty(enableRntbdChannelOverrideString))
                {
                    bool enableRntbdChannel = false;
                    if (bool.TryParse(enableRntbdChannelOverrideString, out enableRntbdChannel))
                    {
                        this.enableRntbdChannel = enableRntbdChannel;
                    }
                }

                string maxRequestsPerRntbdChannelOverrideString = System.Configuration.ConfigurationManager.AppSettings[DocumentClient.MaxRequestsPerChannelConfig];
                if (!string.IsNullOrEmpty(maxRequestsPerRntbdChannelOverrideString))
                {
                    int maxRequestsPerChannel = DocumentClient.DefaultMaxRequestsPerRntbdChannel;
                    if (int.TryParse(maxRequestsPerRntbdChannelOverrideString, out maxRequestsPerChannel))
                    {
                        this.maxRequestsPerRntbdChannel = maxRequestsPerChannel;
                    }
                }

                string rntbdPartitionCountOverrideString = System.Configuration.ConfigurationManager.AppSettings[DocumentClient.TcpPartitionCount];
                if (!string.IsNullOrEmpty(rntbdPartitionCountOverrideString))
                {
                    int rntbdPartitionCount = DocumentClient.DefaultRntbdPartitionCount;
                    if (int.TryParse(rntbdPartitionCountOverrideString, out rntbdPartitionCount))
                    {
                        this.rntbdPartitionCount = rntbdPartitionCount;
                    }
                }

                string maxRntbdChannelsOverrideString = System.Configuration.ConfigurationManager.AppSettings[DocumentClient.MaxChannelsPerHostConfig];
                if (!string.IsNullOrEmpty(maxRntbdChannelsOverrideString))
                {
                    int maxRntbdChannels = DefaultMaxRntbdChannelsPerHost;
                    if (int.TryParse(maxRntbdChannelsOverrideString, out maxRntbdChannels))
                    {
                        this.maxRntbdChannels = maxRntbdChannels;
                    }
                }

                string rntbdPortReuseModeOverrideString = System.Configuration.ConfigurationManager.AppSettings[DocumentClient.RntbdPortReuseMode];
                if (!string.IsNullOrEmpty(rntbdPortReuseModeOverrideString))
                {
                    PortReuseMode portReuseMode = DefaultRntbdPortReuseMode;
                    if (Enum.TryParse<PortReuseMode>(rntbdPortReuseModeOverrideString, out portReuseMode))
                    {
                        this.rntbdPortReuseMode = portReuseMode;
                    }
                }

                string rntbdPortPoolReuseThresholdOverrideString = System.Configuration.ConfigurationManager.AppSettings[DocumentClient.RntbdPortPoolReuseThreshold];
                if (!string.IsNullOrEmpty(rntbdPortPoolReuseThresholdOverrideString))
                {
                    int rntbdPortPoolReuseThreshold = DocumentClient.DefaultRntbdPortPoolReuseThreshold;
                    if (int.TryParse(rntbdPortPoolReuseThresholdOverrideString, out rntbdPortPoolReuseThreshold))
                    {
                        this.rntbdPortPoolReuseThreshold = rntbdPortPoolReuseThreshold;
                    }
                }

                string rntbdPortPoolBindAttemptsOverrideString = System.Configuration.ConfigurationManager.AppSettings[DocumentClient.RntbdPortPoolBindAttempts];
                if (!string.IsNullOrEmpty(rntbdPortPoolBindAttemptsOverrideString))
                {
                    int rntbdPortPoolBindAttempts = DocumentClient.DefaultRntbdPortPoolBindAttempts;
                    if (int.TryParse(rntbdPortPoolBindAttemptsOverrideString, out rntbdPortPoolBindAttempts))
                    {
                        this.rntbdPortPoolBindAttempts = rntbdPortPoolBindAttempts;
                    }
                }

                string rntbdReceiveHangDetectionTimeSecondsString = System.Configuration.ConfigurationManager.AppSettings[DocumentClient.RntbdReceiveHangDetectionTimeConfig];
                if (!string.IsNullOrEmpty(rntbdReceiveHangDetectionTimeSecondsString))
                {
                    int rntbdReceiveHangDetectionTimeSeconds = DefaultRntbdReceiveHangDetectionTimeSeconds;
                    if (int.TryParse(rntbdReceiveHangDetectionTimeSecondsString, out rntbdReceiveHangDetectionTimeSeconds))
                    {
                        this.rntbdReceiveHangDetectionTimeSeconds = rntbdReceiveHangDetectionTimeSeconds;
                    }
                }

                string rntbdSendHangDetectionTimeSecondsString = System.Configuration.ConfigurationManager.AppSettings[DocumentClient.RntbdSendHangDetectionTimeConfig];
                if (!string.IsNullOrEmpty(rntbdSendHangDetectionTimeSecondsString))
                {
                    int rntbdSendHangDetectionTimeSeconds = DefaultRntbdSendHangDetectionTimeSeconds;
                    if (int.TryParse(rntbdSendHangDetectionTimeSecondsString, out rntbdSendHangDetectionTimeSeconds))
                    {
                        this.rntbdSendHangDetectionTimeSeconds = rntbdSendHangDetectionTimeSeconds;
                    }
                }

                if (enableCpuMonitor.HasValue)
                {
                    this.enableCpuMonitor = enableCpuMonitor.Value;
                }
                else
                {
                    string enableCpuMonitorString = System.Configuration.ConfigurationManager.AppSettings[DocumentClient.EnableCpuMonitorConfig];
                    if (!string.IsNullOrEmpty(enableCpuMonitorString))
                    {
                        bool enableCpuMonitorFlag = DefaultEnableCpuMonitor;
                        if (bool.TryParse(enableCpuMonitorString, out enableCpuMonitorFlag))
                        {
                            this.enableCpuMonitor = enableCpuMonitorFlag;
                        }
                    }
                }
#if NETSTANDARD20
            }
#endif
#endif

            string rntbdMaxConcurrentOpeningConnectionCountOverrideString = Environment.GetEnvironmentVariable(RntbdMaxConcurrentOpeningConnectionCountConfig);
            if (!string.IsNullOrEmpty(rntbdMaxConcurrentOpeningConnectionCountOverrideString))
            {
                if (Int32.TryParse(rntbdMaxConcurrentOpeningConnectionCountOverrideString, out int rntbdMaxConcurrentOpeningConnectionCountOverrideInt))
                {
                    if (rntbdMaxConcurrentOpeningConnectionCountOverrideInt <= 0)
                    {
                        throw new ArgumentException("RntbdMaxConcurrentOpeningConnectionCountConfig should be larger than 0");
                    }

                    this.rntbdMaxConcurrentOpeningConnectionCount = rntbdMaxConcurrentOpeningConnectionCountOverrideInt;
                }
            }

            // ConnectionPolicy always overrides appconfig
            if (connectionPolicy != null)
            {
                if (connectionPolicy.IdleTcpConnectionTimeout.HasValue)
                {
                    this.idleConnectionTimeoutInSeconds = (int)connectionPolicy.IdleTcpConnectionTimeout.Value.TotalSeconds;
                }

                if (connectionPolicy.OpenTcpConnectionTimeout.HasValue)
                {
                    this.openConnectionTimeoutInSeconds = (int)connectionPolicy.OpenTcpConnectionTimeout.Value.TotalSeconds;
                }

                if (connectionPolicy.MaxRequestsPerTcpConnection.HasValue)
                {
                    this.maxRequestsPerRntbdChannel = connectionPolicy.MaxRequestsPerTcpConnection.Value;
                }

                if (connectionPolicy.MaxTcpPartitionCount.HasValue)
                {
                    this.rntbdPartitionCount = connectionPolicy.MaxTcpPartitionCount.Value;
                }

                if (connectionPolicy.MaxTcpConnectionsPerEndpoint.HasValue)
                {
                    this.maxRntbdChannels = connectionPolicy.MaxTcpConnectionsPerEndpoint.Value;
                }

                if (connectionPolicy.PortReuseMode.HasValue)
                {
                    this.rntbdPortReuseMode = connectionPolicy.PortReuseMode.Value;
                }
            }

            this.ServiceEndpoint = serviceEndpoint.OriginalString.EndsWith("/", StringComparison.Ordinal) ? serviceEndpoint : new Uri(serviceEndpoint.OriginalString + "/");

            this.ConnectionPolicy = connectionPolicy ?? ConnectionPolicy.Default;

#if !NETSTANDARD16
            ServicePointAccessor servicePoint = ServicePointAccessor.FindServicePoint(this.ServiceEndpoint);
            servicePoint.ConnectionLimit = this.ConnectionPolicy.MaxConnectionLimit;
#endif

            this.GlobalEndpointManager = new GlobalEndpointManager(this, this.ConnectionPolicy);
            this.PartitionKeyRangeLocation = this.ConnectionPolicy.EnablePartitionLevelFailover
                ? new GlobalPartitionEndpointManagerCore(this.GlobalEndpointManager)
                : GlobalPartitionEndpointManagerNoOp.Instance;

            this.httpClient = CosmosHttpClientCore.CreateWithConnectionPolicy(
                this.ApiType,
                DocumentClientEventSource.Instance,
                this.ConnectionPolicy,
                handler,
                this.sendingRequest,
                this.receivedResponse);

            // Loading VM Information (non blocking call and initialization won't fail if this call fails)
            VmMetadataApiHandler.TryInitialize(this.httpClient);

            if (sessionContainer != null)
            {
                this.sessionContainer = sessionContainer;
            }
            else
            {
                this.sessionContainer = new SessionContainer(this.ServiceEndpoint.Host);
            }

            this.retryPolicy = new RetryPolicy(
                globalEndpointManager: this.GlobalEndpointManager,
                connectionPolicy: this.ConnectionPolicy,
                partitionKeyRangeLocationCache: this.PartitionKeyRangeLocation);

            this.ResetSessionTokenRetryPolicy = this.retryPolicy;

            this.desiredConsistencyLevel = desiredConsistencyLevel;
            // Setup the proxy to be  used based on connection mode.
            // For gateway: GatewayProxy.
            // For direct: WFStoreProxy [set in OpenAsync()].
            this.eventSource = DocumentClientEventSource.Instance;

            // Disable system usage for internal builds. Cosmos DB owns the VMs and already logs
            // the system information so no need to track it.
#if !INTERNAL
            this.InitializeClientTelemetry();
#endif

            this.initializeTaskFactory = (_) => TaskHelper.InlineIfPossible<bool>(
                    () => this.GetInitializationTaskAsync(storeClientFactory: storeClientFactory),
                    new ResourceThrottleRetryPolicy(
                        this.ConnectionPolicy.RetryOptions.MaxRetryAttemptsOnThrottledRequests,
                        this.ConnectionPolicy.RetryOptions.MaxRetryWaitTimeInSeconds));

            // Create the task to start the initialize task
            // Task will be awaited on in the EnsureValidClientAsync
            Task initTask = this.initTaskCache.GetAsync(
                       key: DocumentClient.DefaultInitTaskKey,
                       singleValueInitFunc: this.initializeTaskFactory,
                       forceRefresh: (_) => false);

            // ContinueWith on the initialization task is needed for handling the UnobservedTaskException
            // if this task throws for some reason. Awaiting inside a constructor is not supported and
            // even if we had to await inside GetInitializationTask to catch the exception, that will
            // be a blocking call. In such cases, the recommended approach is to "handle" the
            // UnobservedTaskException by using ContinueWith method w/ TaskContinuationOptions.OnlyOnFaulted
            // and accessing the Exception property on the target task.
#pragma warning disable VSTHRD110 // Observe result of async calls
            initTask.ContinueWith(t => DefaultTrace.TraceWarning("initializeTask failed {0}", t.Exception), TaskContinuationOptions.OnlyOnFaulted);
#pragma warning restore VSTHRD110 // Observe result of async calls

            this.traceId = Interlocked.Increment(ref DocumentClient.idCounter);
            DefaultTrace.TraceInformation(string.Format(
                CultureInfo.InvariantCulture,
                "DocumentClient with id {0} initialized at endpoint: {1} with ConnectionMode: {2}, connection Protocol: {3}, and consistency level: {4}",
                this.traceId,
                serviceEndpoint.ToString(),
                this.ConnectionPolicy.ConnectionMode.ToString(),
                this.ConnectionPolicy.ConnectionProtocol.ToString(),
                desiredConsistencyLevel != null ? desiredConsistencyLevel.ToString() : "null"));

            this.QueryCompatibilityMode = QueryCompatibilityMode.Default;
        }

        // Always called from under the lock except when called from Intilialize method during construction.
        private async Task<bool> GetInitializationTaskAsync(IStoreClientFactory storeClientFactory)
        {
            await this.InitializeGatewayConfigurationReaderAsync();

            if (this.desiredConsistencyLevel.HasValue)
            {
                this.EnsureValidOverwrite(this.desiredConsistencyLevel.Value);
            }

            GatewayStoreModel gatewayStoreModel = new GatewayStoreModel(
                    this.GlobalEndpointManager,
                    this.sessionContainer,
                    (Cosmos.ConsistencyLevel)this.accountServiceConfiguration.DefaultConsistencyLevel,
                    this.eventSource,
                    this.serializerSettings,
                    this.httpClient);

            this.GatewayStoreModel = gatewayStoreModel;

            this.collectionCache = new ClientCollectionCache(
                    sessionContainer: this.sessionContainer, 
                    storeModel: this.GatewayStoreModel, 
                    tokenProvider: this, 
                    retryPolicy: this.retryPolicy,
                    clientTelemetry: this.clientTelemetry);
            this.partitionKeyRangeCache = new PartitionKeyRangeCache(this, this.GatewayStoreModel, this.collectionCache);
            this.ResetSessionTokenRetryPolicy = new ResetSessionTokenRetryPolicyFactory(this.sessionContainer, this.collectionCache, this.retryPolicy);

            gatewayStoreModel.SetCaches(this.partitionKeyRangeCache, this.collectionCache);

            if (this.ConnectionPolicy.ConnectionMode == ConnectionMode.Gateway)
            {
                this.StoreModel = this.GatewayStoreModel;
            }
            else
            {
                this.InitializeDirectConnectivity(storeClientFactory);
            }

            return true;
        }

        private void InitializeClientTelemetry()
        {
            if (this.ConnectionPolicy.EnableClientTelemetry)
            {
                try
                {
                    this.clientTelemetry = ClientTelemetry.CreateAndStartBackgroundTelemetry(
                        clientId: this.clientId,
                        httpClient: this.httpClient,
                        userAgent: this.ConnectionPolicy.UserAgentContainer.BaseUserAgent,
                        connectionMode: this.ConnectionPolicy.ConnectionMode,
                        authorizationTokenProvider: this.cosmosAuthorization,
                        diagnosticsHelper: DiagnosticsHandlerHelper.Instance,
                        preferredRegions: this.ConnectionPolicy.PreferredLocations,
                        globalEndpointManager: this.GlobalEndpointManager);

                    DefaultTrace.TraceInformation("Client Telemetry Enabled.");
                }
                catch (Exception ex)
                {
                    DefaultTrace.TraceInformation($"Error While starting Telemetry Job : {ex.Message}. Hence disabling Client Telemetry");
                    this.ConnectionPolicy.EnableClientTelemetry = false;
                }
            }
            else
            {
                DefaultTrace.TraceInformation("Client Telemetry Disabled.");
            }
        }

        private async Task InitializeCachesAsync(string databaseName, DocumentCollection collection, CancellationToken cancellationToken)
        {
            if (databaseName == null)
            {
                throw new ArgumentNullException(nameof(databaseName));
            }

            if (collection == null)
            {
                throw new ArgumentNullException(nameof(collection));
            }

            CollectionCache collectionCache = await this.GetCollectionCacheAsync(NoOpTrace.Singleton);
            using (
                DocumentServiceRequest request = DocumentServiceRequest.Create(
                    OperationType.Query,
                    ResourceType.Document,
                    collection.SelfLink,
                    AuthorizationTokenType.PrimaryMasterKey))
            {
                ContainerProperties resolvedCollection = await collectionCache.ResolveCollectionAsync(request, CancellationToken.None, NoOpTrace.Singleton);
                IReadOnlyList<PartitionKeyRange> ranges = await this.partitionKeyRangeCache.TryGetOverlappingRangesAsync(
                    resolvedCollection.ResourceId,
                    new Range<string>(
                        PartitionKeyInternal.MinimumInclusiveEffectivePartitionKey,
                        PartitionKeyInternal.MaximumExclusiveEffectivePartitionKey,
                        true,
                        false),
                    NoOpTrace.Singleton);

                // In Gateway mode, AddressCache is null
                if (this.AddressResolver != null)
                {
                    await this.AddressResolver.OpenAsync(databaseName, resolvedCollection, cancellationToken);
                }
            }
        }

        /// <summary>
        /// Gets or sets the session object used for session consistency version tracking in the Azure Cosmos DB service.
        /// </summary>
        /// <remarks>
        /// <value>
        /// The session object used for version tracking when the consistency level is set to Session.
        /// </value>
        /// The session object can be saved and shared between two DocumentClient instances within the same AppDomain.
        /// </remarks>
        public object Session
        {
            get
            {
                return this.sessionContainer;
            }

            set
            {
                SessionContainer container = value as SessionContainer;
                if (container == null)
                {
                    throw new ArgumentNullException("value");
                }

                if (!string.Equals(this.ServiceEndpoint.Host, container.HostName, StringComparison.OrdinalIgnoreCase))
                {
                    throw new ArgumentException(string.Format(
                        CultureInfo.CurrentUICulture,
                        ClientResources.BadSession,
                        container.HostName,
                        this.ServiceEndpoint.Host));
                }

                SessionContainer currentSessionContainer = this.sessionContainer as SessionContainer;
                if (currentSessionContainer == null)
                {
                    throw new ArgumentNullException(nameof(currentSessionContainer));
                }

                currentSessionContainer.ReplaceCurrrentStateWithStateOf(container);
            }
        }

        /// <summary>
        /// Gets or sets the session object used for session consistency version tracking for a specific collection in the Azure Cosmos DB service.
        /// </summary>
        /// <param name="collectionLink">Collection for which session token must be retrieved.</param>
        /// <value>
        /// The session token used for version tracking when the consistency level is set to Session.
        /// </value>
        /// <remarks>
        /// The session token can be saved and supplied to a request via <see cref="Documents.Client.RequestOptions.SessionToken"/>.
        /// </remarks>
        internal string GetSessionToken(string collectionLink)
        {
            SessionContainer sessionContainerInternal = this.sessionContainer as SessionContainer;

            if (sessionContainerInternal == null)
            {
                throw new ArgumentNullException(nameof(sessionContainerInternal));
            }

            return sessionContainerInternal.GetSessionToken(collectionLink);
        }

        /// <summary>
        /// Gets the Api type
        /// </summary>
        internal ApiType ApiType
        {
            get; private set;
        }

        internal bool UseMultipleWriteLocations { get; private set; }

        /// <summary>
        /// Gets the endpoint Uri for the service endpoint from the Azure Cosmos DB service.
        /// </summary>
        /// <value>
        /// The Uri for the service endpoint.
        /// </value>
        /// <seealso cref="System.Uri"/>
        public Uri ServiceEndpoint
        {
            get;
            private set;
        }

        /// <summary>
        /// Gets the current write endpoint chosen based on availability and preference from the Azure Cosmos DB service.
        /// </summary>
        public Uri WriteEndpoint
        {
            get
            {
                return this.GlobalEndpointManager.WriteEndpoints.FirstOrDefault();
            }
        }

        /// <summary>
        /// Gets the current read endpoint chosen based on availability and preference from the Azure Cosmos DB service.
        /// </summary>
        public Uri ReadEndpoint
        {
            get
            {
                return this.GlobalEndpointManager.ReadEndpoints.FirstOrDefault();
            }
        }

        /// <summary>
        /// Gets the Connection policy used by the client from the Azure Cosmos DB service.
        /// </summary>
        /// <value>
        /// The Connection policy used by the client.
        /// </value>
        /// <seealso cref="Microsoft.Azure.Cosmos.ConnectionPolicy"/>
        public ConnectionPolicy ConnectionPolicy { get; private set; }

        /// <summary>
        /// Gets the AuthKey used by the client from the Azure Cosmos DB service.
        /// </summary>
        /// <value>
        /// The AuthKey used by the client.
        /// </value>
        /// <seealso cref="System.Security.SecureString"/>
        public SecureString AuthKey => throw new NotSupportedException("Please use CosmosAuthorization");

        /// <summary>
        /// Gets the configured consistency level of the client from the Azure Cosmos DB service.
        /// </summary>
        /// <value>
        /// The configured <see cref="Microsoft.Azure.Cosmos.ConsistencyLevel"/> of the client.
        /// </value>
        /// <seealso cref="Microsoft.Azure.Cosmos.ConsistencyLevel"/>
        public virtual Documents.ConsistencyLevel ConsistencyLevel
        {
            get
            {
#pragma warning disable VSTHRD002 // Avoid problematic synchronous waits
                TaskHelper.InlineIfPossibleAsync(() => this.EnsureValidClientAsync(NoOpTrace.Singleton), null).Wait();
#pragma warning restore VSTHRD002 // Avoid problematic synchronous waits
                return this.desiredConsistencyLevel.HasValue ? this.desiredConsistencyLevel.Value :
                    this.accountServiceConfiguration.DefaultConsistencyLevel;
            }
        }

        /// <summary>
        /// Disposes the client for the Azure Cosmos DB service.
        /// </summary>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// IDocumentClient client = new DocumentClient(new Uri("service endpoint"), "auth key");
        /// if (client != null) client.Dispose();
        /// ]]>
        /// </code>
        /// </example>
        public void Dispose()
        {
            if (this.isDisposed)
            {
                return;
            }

            if (!this.cancellationTokenSource.IsCancellationRequested)
            {
                this.cancellationTokenSource.Cancel();
            }

            this.cancellationTokenSource.Dispose();

            if (this.StoreModel != null)
            {
                this.StoreModel.Dispose();
                this.StoreModel = null;
            }

            if (this.storeClientFactory != null)
            {
                // Dispose only if this store client factory was created and is owned by this instance of document client, otherwise just release the reference
                if (this.isStoreClientFactoryCreatedInternally)
                {
                    this.storeClientFactory.Dispose();
                }

                this.storeClientFactory = null;
            }

            if (this.AddressResolver != null)
            {
                this.AddressResolver.Dispose();
                this.AddressResolver = null;
            }

            if (this.httpClient != null)
            {
                try
                {
                    this.httpClient.Dispose();
                }
                catch (Exception exception)
                {
                    DefaultTrace.TraceWarning("Exception {0} thrown during dispose of HttpClient, this could happen if there are inflight request during the dispose of client",
                        exception);
                }

                this.httpClient = null;
            }

            if (this.cosmosAuthorization != null)
            {
                this.cosmosAuthorization.Dispose();
            }

            if (this.GlobalEndpointManager != null)
            {
                this.GlobalEndpointManager.Dispose();
                this.GlobalEndpointManager = null;
            }

            if (this.queryPartitionProvider != null && this.queryPartitionProvider.IsValueCreated)
            {
                this.queryPartitionProvider.Value.Dispose();
            }

            if (this.initTaskCache != null)
            {
                this.initTaskCache.Dispose();
                this.initTaskCache = null;
            }

            if (this.clientTelemetry != null)
            {
                this.clientTelemetry.Dispose();
            }

            DefaultTrace.TraceInformation("DocumentClient with id {0} disposed.", this.traceId);
            DefaultTrace.Flush();

            this.isDisposed = true;
        }

        //Compatibility mode:
        // Allows to specify compatibility mode used by client when making query requests.
        // should be removed when application/sql is no longer supported.
        internal QueryCompatibilityMode QueryCompatibilityMode { get; set; }

        /// <summary>
        /// RetryPolicy retries a request when it encounters session unavailable (see ClientRetryPolicy).
        /// Once it exhausts all write regions it clears the session container, then it uses ClientCollectionCache
        /// to resolves the request's collection name. If it differs from the session container's resource id it
        /// explains the session unavailable exception: somebody removed and recreated the collection. In this
        /// case we retry once again (with empty session token) otherwise we return the error to the client
        /// (see RenameCollectionAwareClientRetryPolicy)
        /// </summary>
        internal virtual IRetryPolicyFactory ResetSessionTokenRetryPolicy { get; private set; }

        /// <summary>
        /// Gets and sets the IStoreModel object.
        /// </summary>
        /// <remarks>
        /// Test hook to enable unit test of DocumentClient.
        /// </remarks>
        internal IStoreModelExtension StoreModel { get; set; }

        /// <summary>
        /// Gets and sets the gateway IStoreModel object.
        /// </summary>
        /// <remarks>
        /// Test hook to enable unit test of DocumentClient.
        /// </remarks>
        internal IStoreModelExtension GatewayStoreModel { get; set; }

        /// <summary>
        /// Gets and sets on execute scalar query callback
        /// </summary>
        /// <remarks>
        /// Test hook to enable unit test for scalar queries
        /// </remarks>
        internal Action<IQueryable> OnExecuteScalarQueryCallback { get; set; }

        internal virtual Task<QueryPartitionProvider> QueryPartitionProvider => this.queryPartitionProvider.Value;

        internal virtual async Task<ConsistencyLevel> GetDefaultConsistencyLevelAsync()
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);
            return (ConsistencyLevel)this.accountServiceConfiguration.DefaultConsistencyLevel;
        }

        internal Task<Documents.ConsistencyLevel?> GetDesiredConsistencyLevelAsync()
        {
            return Task.FromResult<Documents.ConsistencyLevel?>(this.desiredConsistencyLevel);
        }

        internal async Task<DocumentServiceResponse> ProcessRequestAsync(
            string verb,
            DocumentServiceRequest request,
            IDocumentClientRetryPolicy retryPolicyInstance,
            CancellationToken cancellationToken,
            string testAuthorization = null) // Only for unit-tests
        {
            if (request == null)
            {
                throw new ArgumentNullException(nameof(request));
            }

            if (verb == null)
            {
                throw new ArgumentNullException(nameof(verb));
            }

            (string authorization, string payload) = await this.cosmosAuthorization.GetUserAuthorizationAsync(
                request.ResourceAddress,
                PathsHelper.GetResourcePath(request.ResourceType),
                verb,
                request.Headers,
                AuthorizationTokenType.PrimaryMasterKey);

            // Unit-test hook
            if (testAuthorization != null)
            {
                payload = testAuthorization;
                authorization = testAuthorization;
            }
            request.Headers[HttpConstants.HttpHeaders.Authorization] = authorization;

            try
            {
                return await this.ProcessRequestAsync(request, retryPolicyInstance, cancellationToken);
            }
            catch (DocumentClientException dce)
            {
                this.cosmosAuthorization.TraceUnauthorized(
                    dce,
                    authorization,
                    payload);

                throw;
            }
        }

        internal Task<DocumentServiceResponse> ProcessRequestAsync(
            DocumentServiceRequest request,
            IDocumentClientRetryPolicy retryPolicyInstance,
            CancellationToken cancellationToken)
        {
            return this.ProcessRequestAsync(request, retryPolicyInstance, NoOpTrace.Singleton, cancellationToken);
        }

        internal async Task<DocumentServiceResponse> ProcessRequestAsync(
            DocumentServiceRequest request,
            IDocumentClientRetryPolicy retryPolicyInstance,
            ITrace trace,
            CancellationToken cancellationToken)
        {
            await this.EnsureValidClientAsync(trace);

            retryPolicyInstance?.OnBeforeSendRequest(request);

            using (new ActivityScope(Guid.NewGuid()))
            {
                IStoreModel storeProxy = this.GetStoreProxy(request);
                return await storeProxy.ProcessMessageAsync(request, cancellationToken);
            }
        }

        /// <summary>
        /// Establishes and Initializes the Rntbd connection to all the backend replica nodes
        /// for the given database name and container.
        /// </summary>
        /// <param name="databaseName">A string containing the cosmos database name.</param>
        /// <param name="containerLinkUri">A string containing the cosmos container link uri.</param>
        /// <param name="cancellationToken">An instance of the <see cref="CancellationToken"/>.</param>
        internal async Task OpenConnectionsToAllReplicasAsync(
            string databaseName,
            string containerLinkUri,
            CancellationToken cancellationToken)
        {
            if (string.IsNullOrEmpty(databaseName) ||
                string.IsNullOrEmpty(containerLinkUri))
            {
                string resourceName = string.IsNullOrEmpty(databaseName) ?
                    nameof(databaseName) :
                    nameof(containerLinkUri);

                throw new ArgumentNullException(resourceName);
            }

            if (this.StoreModel != null)
            {
                try
                {
                    await this.StoreModel.OpenConnectionsToAllReplicasAsync(
                        databaseName,
                        containerLinkUri,
                        cancellationToken);
                }
                catch (Exception)
                {
                    throw;
                }
            }
        }

        private static string NormalizeAuthorizationPayload(string input)
        {
            const int expansionBuffer = 12;
            StringBuilder builder = new StringBuilder(input.Length + expansionBuffer);
            for (int i = 0; i < input.Length; i++)
            {
                switch (input[i])
                {
                    case '\n':
                        builder.Append("\\n");
                        break;
                    case '/':
                        builder.Append("\\/");
                        break;
                    default:
                        builder.Append(input[i]);
                        break;
                }
            }

            return builder.ToString();
        }

        internal RntbdConnectionConfig RecordTcpSettings(ClientConfigurationTraceDatum clientConfigurationTraceDatum)
        {
            return new RntbdConnectionConfig(this.openConnectionTimeoutInSeconds,
                                this.idleConnectionTimeoutInSeconds,
                                this.maxRequestsPerRntbdChannel,
                                this.maxRntbdChannels,
                                this.ConnectionPolicy.EnableTcpConnectionEndpointRediscovery,
                                this.rntbdPortReuseMode);
        }

        internal virtual async Task EnsureValidClientAsync(ITrace trace)
        {
            if (this.cancellationTokenSource.IsCancellationRequested || this.isSuccessfullyInitialized)
            {
                return;
            }

            // Trace when the Initialization of client has not been completed. Usually during first call
            using (ITrace childTrace = trace.StartChild("Waiting for Initialization of client to complete", TraceComponent.Unknown, Tracing.TraceLevel.Info))
            {
                // If the initialization task failed, we should retry initialization.
                // We may end up throwing the same exception but this will ensure that we dont have a
                // client which is unusable and can resume working if it failed initialization once.
                // If we have to reinitialize the client, it needs to happen in thread safe manner so that
                // we dont re-initalize the task again for each incoming call.
                try
                {
                    this.isSuccessfullyInitialized = await this.initTaskCache.GetAsync(
                        key: DocumentClient.DefaultInitTaskKey,
                        singleValueInitFunc: this.initializeTaskFactory,
                        forceRefresh: (_) => false);
                }
                catch (DocumentClientException ex)
                {
                    throw Resource.CosmosExceptions.CosmosExceptionFactory.Create(
                         dce: ex,
                         trace: trace);
                }
                catch (Exception e)
                {
                    DefaultTrace.TraceWarning("EnsureValidClientAsync initializeTask failed {0}", e);
                    childTrace.AddDatum("initializeTask failed", e);
                    throw;
                }
            }
        }

        #region Create Impl
        /// <summary>
        /// Creates a database resource as an asychronous operation in the Azure Cosmos DB service.
        /// </summary>
        /// <param name="database">The specification for the <see cref="Database"/> to create.</param>
        /// <param name="options">(Optional) The <see cref="Documents.Client.RequestOptions"/> for the request.</param>
        /// <returns>The <see cref="Database"/> that was created within a task object representing the service response for the asynchronous operation.</returns>
        /// <exception cref="ArgumentNullException">If <paramref name="database"/> is not set.</exception>
        /// <exception cref="System.AggregateException">Represents a consolidation of failures that occured during async processing. Look within InnerExceptions to find the actual exception(s).</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Database are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>400</term><description>BadRequest - This means something was wrong with the database object supplied. It is likely that an id was not supplied for the new Database.</description>
        ///     </item>
        ///     <item>
        ///         <term>409</term><description>Conflict - This means a <see cref="Database"/> with an id matching the id field of <paramref name="database"/> already existed.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// The example below creates a new <see cref="Database"/> with an Id property of 'MyDatabase'
        /// This code snippet is intended to be used from within an asynchronous method as it uses the await keyword
        /// <code language="c#">
        /// <![CDATA[
        /// using (IDocumentClient client = new DocumentClient(new Uri("service endpoint"), "auth key"))
        /// {
        ///     Database db = await client.CreateDatabaseAsync(new Database { Id = "MyDatabase" });
        /// }
        /// ]]>
        /// </code>
        /// </example>
        /// <example>
        /// If you would like to construct a <see cref="Database"/> from within a synchronous method then you need to use the following code
        /// <code language="c#">
        /// <![CDATA[
        /// using (IDocumentClient client = new DocumentClient(new Uri("service endpoint"), "auth key"))
        /// {
        ///     Database db = client.CreateDatabaseAsync(new Database { Id = "MyDatabase" }).Result;
        /// }
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.Database"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<ResourceResponse<Documents.Database>> CreateDatabaseAsync(Documents.Database database, Documents.Client.RequestOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(() => this.CreateDatabasePrivateAsync(database, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<Documents.Database>> CreateDatabasePrivateAsync(Documents.Database database, Documents.Client.RequestOptions options, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (database == null)
            {
                throw new ArgumentNullException("database");
            }

            this.ValidateResource(database);

            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Create, ResourceType.Database);

            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Create,
                Paths.Databases_Root,
                database,
                ResourceType.Database,
                AuthorizationTokenType.PrimaryMasterKey,
                headers,
                SerializationFormattingPolicy.None))
            {
                return new ResourceResponse<Documents.Database>(await this.CreateAsync(request, retryPolicyInstance));
            }
        }

        /// <summary>
        /// Creates(if doesn't exist) or gets(if already exists) a database resource as an asychronous operation in the Azure Cosmos DB service.
        /// You can check the status code from the response to determine whether the database was newly created(201) or existing database was returned(200)
        /// </summary>
        /// <param name="database">The specification for the <see cref="Database"/> to create.</param>
        /// <param name="options">(Optional) The <see cref="Documents.Client.RequestOptions"/> for the request.</param>
        /// <returns>The <see cref="Database"/> that was created within a task object representing the service response for the asynchronous operation.</returns>
        /// <exception cref="ArgumentNullException">If <paramref name="database"/> is not set.</exception>
        /// <exception cref="System.AggregateException">Represents a consolidation of failures that occured during async processing. Look within InnerExceptions to find the actual exception(s).</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property.</exception>
        /// <example>
        /// The example below creates a new <see cref="Database"/> with an Id property of 'MyDatabase'
        /// This code snippet is intended to be used from within an asynchronous method as it uses the await keyword
        /// <code language="c#">
        /// <![CDATA[
        /// using (IDocumentClient client = new DocumentClient(new Uri("service endpoint"), "auth key"))
        /// {
        ///     Database db = await client.CreateDatabaseIfNotExistsAsync(new Database { Id = "MyDatabase" });
        /// }
        /// ]]>
        /// </code>
        /// </example>
        /// <example>
        /// If you would like to construct a <see cref="Database"/> from within a synchronous method then you need to use the following code
        /// <code language="c#">
        /// <![CDATA[
        /// using (IDocumentClient client = new DocumentClient(new Uri("service endpoint"), "auth key"))
        /// {
        ///     Database db = client.CreateDatabaseIfNotExistsAsync(new Database { Id = "MyDatabase" }).Result;
        /// }
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.Database"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<ResourceResponse<Documents.Database>> CreateDatabaseIfNotExistsAsync(Documents.Database database, Documents.Client.RequestOptions options = null)
        {
            return TaskHelper.InlineIfPossible(() => this.CreateDatabaseIfNotExistsPrivateAsync(database, options), null);
        }

        private async Task<ResourceResponse<Documents.Database>> CreateDatabaseIfNotExistsPrivateAsync(Documents.Database database,
            Documents.Client.RequestOptions options)
        {
            if (database == null)
            {
                throw new ArgumentNullException("database");
            }

            // Doing a Read before Create will give us better latency for existing databases
            try
            {
                return await this.ReadDatabaseAsync(UriFactory.CreateDatabaseUri(database.Id));
            }
            catch (DocumentClientException dce)
            {
                if (dce.StatusCode != HttpStatusCode.NotFound)
                {
                    throw;
                }
            }

            try
            {
                return await this.CreateDatabaseAsync(database, options);
            }
            catch (DocumentClientException ex)
            {
                if (ex.StatusCode != HttpStatusCode.Conflict)
                {
                    throw;
                }
            }

            // This second Read is to handle the race condition when 2 or more threads have Read the database and only one succeeds with Create
            // so for the remaining ones we should do a Read instead of throwing Conflict exception
            return await this.ReadDatabaseAsync(UriFactory.CreateDatabaseUri(database.Id));
        }

        /// <summary>
        /// Creates a Document as an asychronous operation in the Azure Cosmos DB service.
        /// </summary>
        /// <param name="documentsFeedOrDatabaseLink">The link of the <see cref="DocumentCollection"/> to create the document in. E.g. dbs/db_rid/colls/coll_rid/ </param>
        /// <param name="document">The document object to create.</param>
        /// <param name="options">(Optional) Any request options you wish to set. E.g. Specifying a Trigger to execute when creating the document. <see cref="Documents.Client.RequestOptions"/></param>
        /// <param name="disableAutomaticIdGeneration">(Optional) Disables the automatic id generation, If this is True the system will throw an exception if the id property is missing from the Document.</param>
        /// <param name="cancellationToken">(Optional) A <see cref="CancellationToken"/> that can be used by other objects or threads to receive notice of cancellation.</param>
        /// <returns>The <see cref="Microsoft.Azure.Documents.Document"/> that was created contained within a <see cref="System.Threading.Tasks.Task"/> object representing the service response for the asynchronous operation.</returns>
        /// <exception cref="ArgumentNullException">If either <paramref name="documentsFeedOrDatabaseLink"/> or <paramref name="document"/> is not set.</exception>
        /// <exception cref="System.AggregateException">Represents a consolidation of failures that occured during async processing. Look within InnerExceptions to find the actual exception(s)</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>400</term><description>BadRequest - This means something was wrong with the document supplied. It is likely that <paramref name="disableAutomaticIdGeneration"/> was true and an id was not supplied</description>
        ///     </item>
        ///     <item>
        ///         <term>403</term><description>Forbidden - This likely means the collection in to which you were trying to create the document is full.</description>
        ///     </item>
        ///     <item>
        ///         <term>409</term><description>Conflict - This means a <see cref="Document"/> with an id matching the id field of <paramref name="document"/> already existed</description>
        ///     </item>
        ///     <item>
        ///         <term>413</term><description>RequestEntityTooLarge - This means the <see cref="Document"/> exceeds the current max entity size. Consult documentation for limits and quotas.</description>
        ///     </item>
        ///     <item>
        ///         <term>429</term><description>TooManyRequests - This means you have exceeded the number of request units per second. Consult the DocumentClientException.RetryAfter value to see how long you should wait before retrying this operation.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// Azure Cosmos DB supports a number of different ways to work with documents. A document can extend <see cref="Resource"/>
        /// <code language="c#">
        /// <![CDATA[
        /// public class MyObject : Resource
        /// {
        ///     public string MyProperty {get; set;}
        /// }
        ///
        /// using (IDocumentClient client = new DocumentClient(new Uri("service endpoint"), "auth key"))
        /// {
        ///     Document doc = await client.CreateDocumentAsync("dbs/db_rid/colls/coll_rid/", new MyObject { MyProperty = "A Value" });
        /// }
        /// ]]>
        /// </code>
        /// </example>
        /// <example>
        /// A document can be any POCO object that can be serialized to JSON, even if it doesn't extend from <see cref="Resource"/>
        /// <code language="c#">
        /// <![CDATA[
        /// public class MyPOCO
        /// {
        ///     public string MyProperty {get; set;}
        /// }
        ///
        /// using (IDocumentClient client = new DocumentClient(new Uri("service endpoint"), "auth key"))
        /// {
        ///     Document doc = await client.CreateDocumentAsync("dbs/db_rid/colls/coll_rid/", new MyPOCO { MyProperty = "A Value" });
        /// }
        /// ]]>
        /// </code>
        /// </example>
        /// <example>
        /// Finally, a Document can also be a dynamic object
        /// <code language="c#">
        /// <![CDATA[
        /// using (IDocumentClient client = new DocumentClient(new Uri("service endpoint"), "auth key"))
        /// {
        ///     Document doc = await client.CreateDocumentAsync("dbs/db_rid/colls/coll_rid/", new { SomeProperty = "A Value" } );
        /// }
        /// ]]>
        /// </code>
        /// </example>
        /// <example>
        /// Create a Document and execute a Pre and Post Trigger
        /// <code language="c#">
        /// <![CDATA[
        /// using (IDocumentClient client = new DocumentClient(new Uri("service endpoint"), "auth key"))
        /// {
        ///     Document doc = await client.CreateDocumentAsync(
        ///         "dbs/db_rid/colls/coll_rid/",
        ///         new { id = "DOC123213443" },
        ///         new RequestOptions
        ///         {
        ///             PreTriggerInclude = new List<string> { "MyPreTrigger" },
        ///             PostTriggerInclude = new List<string> { "MyPostTrigger" }
        ///         });
        /// }
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.Document"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<ResourceResponse<Document>> CreateDocumentAsync(string documentsFeedOrDatabaseLink,
            object document, Documents.Client.RequestOptions options = null, bool disableAutomaticIdGeneration = false,
            CancellationToken cancellationToken = default)
        {
            // This call is to just run CreateDocumentInlineAsync in a SynchronizationContext aware environment
            return TaskHelper.InlineIfPossible(() => this.CreateDocumentInlineAsync(documentsFeedOrDatabaseLink, document, options, disableAutomaticIdGeneration, cancellationToken), null, cancellationToken);
        }

        private async Task<ResourceResponse<Document>> CreateDocumentInlineAsync(string documentsFeedOrDatabaseLink, object document, Documents.Client.RequestOptions options, bool disableAutomaticIdGeneration, CancellationToken cancellationToken)
        {
            IDocumentClientRetryPolicy requestRetryPolicy = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            if (options?.PartitionKey == null)
            {
                requestRetryPolicy = new PartitionKeyMismatchRetryPolicy(
                    await this.GetCollectionCacheAsync(NoOpTrace.Singleton), 
                    requestRetryPolicy);
            }

            return await TaskHelper.InlineIfPossible(() => this.CreateDocumentPrivateAsync(
                documentsFeedOrDatabaseLink,
                document,
                options,
                disableAutomaticIdGeneration,
                requestRetryPolicy,
                cancellationToken), requestRetryPolicy);
        }

        private async Task<ResourceResponse<Document>> CreateDocumentPrivateAsync(
            string documentCollectionLink,
            object document,
            Documents.Client.RequestOptions options,
            bool disableAutomaticIdGeneration,
            IDocumentClientRetryPolicy retryPolicyInstance,
            CancellationToken cancellationToken)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(documentCollectionLink))
            {
                throw new ArgumentNullException("documentCollectionLink");
            }

            if (document == null)
            {
                throw new ArgumentNullException("document");
            }

            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Create, ResourceType.Document);
            Document typedDocument = Document.FromObject(document, this.GetSerializerSettingsForRequest(options));

            this.ValidateResource(typedDocument);

            if (string.IsNullOrEmpty(typedDocument.Id) && !disableAutomaticIdGeneration)
            {
                typedDocument.Id = Guid.NewGuid().ToString();
            }

            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Create,
                documentCollectionLink,
                typedDocument,
                ResourceType.Document,
                AuthorizationTokenType.PrimaryMasterKey,
                headers,
                SerializationFormattingPolicy.None,
                this.GetSerializerSettingsForRequest(options)))
            {
                await this.AddPartitionKeyInformationAsync(request, typedDocument, options);
                return new ResourceResponse<Document>(await this.CreateAsync(request, retryPolicyInstance, cancellationToken));
            }
        }

        /// <summary>
        /// Creates a collection as an asychronous operation in the Azure Cosmos DB service.
        /// </summary>
        /// <param name="databaseLink">The link of the database to create the collection in. E.g. dbs/db_rid/.</param>
        /// <param name="documentCollection">The <see cref="Microsoft.Azure.Documents.DocumentCollection"/> object.</param>
        /// <param name="options">(Optional) Any <see cref="Microsoft.Azure.Documents.Client.RequestOptions"/> you wish to provide when creating a Collection. E.g. RequestOptions.OfferThroughput = 400. </param>
        /// <returns>The <see cref="Microsoft.Azure.Documents.DocumentCollection"/> that was created contained within a <see cref="System.Threading.Tasks.Task"/> object representing the service response for the asynchronous operation.</returns>
        /// <exception cref="ArgumentNullException">If either <paramref name="databaseLink"/> or <paramref name="documentCollection"/> is not set.</exception>
        /// <exception cref="System.AggregateException">Represents a consolidation of failures that occured during async processing. Look within InnerExceptions to find the actual exception(s).</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a collection are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>400</term><description>BadRequest - This means something was wrong with the request supplied. It is likely that an id was not supplied for the new collection.</description>
        ///     </item>
        ///     <item>
        ///         <term>403</term><description>Forbidden - This means you attempted to exceed your quota for collections. Contact support to have this quota increased.</description>
        ///     </item>
        ///     <item>
        ///         <term>409</term><description>Conflict - This means a <see cref="Microsoft.Azure.Documents.DocumentCollection"/> with an id matching the id you supplied already existed.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        ///
        /// <code language="c#">
        /// <![CDATA[
        /// using (IDocumentClient client = new DocumentClient(new Uri("service endpoint"), "auth key"))
        /// {
        ///     //Create a new collection with an OfferThroughput set to 10000
        ///     //Not passing in RequestOptions.OfferThroughput will result in a collection with the default OfferThroughput set.
        ///     DocumentCollection coll = await client.CreateDocumentCollectionAsync(databaseLink,
        ///         new DocumentCollection { Id = "My Collection" },
        ///         new RequestOptions { OfferThroughput = 10000} );
        /// }
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.DocumentCollection"/>
        /// <seealso cref="Microsoft.Azure.Documents.OfferV2"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<ResourceResponse<DocumentCollection>> CreateDocumentCollectionAsync(string databaseLink, DocumentCollection documentCollection, Documents.Client.RequestOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(() => this.CreateDocumentCollectionPrivateAsync(databaseLink, documentCollection, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<DocumentCollection>> CreateDocumentCollectionPrivateAsync(
            string databaseLink,
            DocumentCollection documentCollection,
            Documents.Client.RequestOptions options,
            IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(databaseLink))
            {
                throw new ArgumentNullException("databaseLink");
            }

            if (documentCollection == null)
            {
                throw new ArgumentNullException("documentCollection");
            }

            this.ValidateResource(documentCollection);
            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Create, ResourceType.Collection);
            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Create,
                databaseLink,
                documentCollection,
                ResourceType.Collection,
                AuthorizationTokenType.PrimaryMasterKey,
                headers,
                SerializationFormattingPolicy.None))
            {
                ResourceResponse<DocumentCollection> collection = new ResourceResponse<DocumentCollection>(
                    await this.CreateAsync(request, retryPolicyInstance));
                // set the session token
                this.sessionContainer.SetSessionToken(collection.Resource.ResourceId, collection.Resource.AltLink, collection.Headers);
                return collection;
            }
        }

        /// <summary>
        /// Creates (if doesn't exist) or gets (if already exists) a collection as an asychronous operation in the Azure Cosmos DB service.
        /// You can check the status code from the response to determine whether the collection was newly created (201) or existing collection was returned (200).
        /// </summary>
        /// <param name="databaseLink">The link of the database to create the collection in. E.g. dbs/db_rid/.</param>
        /// <param name="documentCollection">The <see cref="Microsoft.Azure.Documents.DocumentCollection"/> object.</param>
        /// <param name="options">(Optional) Any <see cref="Microsoft.Azure.Documents.Client.RequestOptions"/> you wish to provide when creating a Collection. E.g. RequestOptions.OfferThroughput = 400. </param>
        /// <returns>The <see cref="Microsoft.Azure.Documents.DocumentCollection"/> that was created contained within a <see cref="System.Threading.Tasks.Task"/> object representing the service response for the asynchronous operation.</returns>
        /// <exception cref="ArgumentNullException">If either <paramref name="databaseLink"/> or <paramref name="documentCollection"/> is not set.</exception>
        /// <exception cref="System.AggregateException">Represents a consolidation of failures that occured during async processing. Look within InnerExceptions to find the actual exception(s).</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a DocumentCollection are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>400</term><description>BadRequest - This means something was wrong with the request supplied. It is likely that an id was not supplied for the new collection.</description>
        ///     </item>
        ///     <item>
        ///         <term>403</term><description>Forbidden - This means you attempted to exceed your quota for collections. Contact support to have this quota increased.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        ///
        /// <code language="c#">
        /// <![CDATA[
        /// using (IDocumentClient client = new DocumentClient(new Uri("service endpoint"), "auth key"))
        /// {
        ///     //Create a new collection with an OfferThroughput set to 10000
        ///     //Not passing in RequestOptions.OfferThroughput will result in a collection with the default OfferThroughput set.
        ///     DocumentCollection coll = await client.CreateDocumentCollectionIfNotExistsAsync(databaseLink,
        ///         new DocumentCollection { Id = "My Collection" },
        ///         new RequestOptions { OfferThroughput = 10000} );
        /// }
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.DocumentCollection"/>
        /// <seealso cref="Microsoft.Azure.Documents.OfferV2"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<ResourceResponse<DocumentCollection>> CreateDocumentCollectionIfNotExistsAsync(string databaseLink, DocumentCollection documentCollection, Documents.Client.RequestOptions options = null)
        {
            return TaskHelper.InlineIfPossible(() => this.CreateDocumentCollectionIfNotExistsPrivateAsync(databaseLink, documentCollection, options), null);
        }

        private async Task<ResourceResponse<DocumentCollection>> CreateDocumentCollectionIfNotExistsPrivateAsync(
            string databaseLink, DocumentCollection documentCollection, Documents.Client.RequestOptions options)
        {
            if (string.IsNullOrEmpty(databaseLink))
            {
                throw new ArgumentNullException("databaseLink");
            }

            if (documentCollection == null)
            {
                throw new ArgumentNullException("documentCollection");
            }

            // ReadDatabaseAsync call is needed to support this API that takes databaseLink as a parameter, to be consistent with CreateDocumentCollectionAsync. We need to construct the collectionLink to make
            // ReadDocumentCollectionAsync call, in case database selfLink got passed to this API. We cannot simply concat the database selfLink with /colls/{collectionId} to get the collectionLink.
            Documents.Database database = await this.ReadDatabaseAsync(databaseLink);

            // Doing a Read before Create will give us better latency for existing collections.
            // Also, in emulator case when you hit the max allowed partition count and you use this API for a collection that already exists,
            // calling Create will throw 503(max capacity reached) even though the intent of this API is to return the collection if it already exists.
            try
            {
                return await this.ReadDocumentCollectionAsync(UriFactory.CreateDocumentCollectionUri(database.Id, documentCollection.Id), null);
            }
            catch (DocumentClientException dce)
            {
                if (dce.StatusCode != HttpStatusCode.NotFound)
                {
                    throw;
                }
            }

            try
            {
                return await this.CreateDocumentCollectionAsync(databaseLink, documentCollection, options);
            }
            catch (DocumentClientException ex)
            {
                if (ex.StatusCode != HttpStatusCode.Conflict)
                {
                    throw;
                }
            }

            // This second Read is to handle the race condition when 2 or more threads have Read the collection and only one succeeds with Create
            // so for the remaining ones we should do a Read instead of throwing Conflict exception
            return await this.ReadDocumentCollectionAsync(UriFactory.CreateDocumentCollectionUri(database.Id, documentCollection.Id), null);
        }

        /// <summary>
        /// Restores a collection as an asychronous operation in the Azure Cosmos DB service.
        /// </summary>
        /// <param name="sourceDocumentCollectionLink">The link to the source <see cref="DocumentCollection"/> object.</param>
        /// <param name="targetDocumentCollection">The target <see cref="DocumentCollection"/> object.</param>
        /// <param name="restoreTime">(optional)The point in time to restore. If null, use the latest restorable time. </param>
        /// <param name="options">(Optional) The <see cref="Documents.Client.RequestOptions"/> for the request.</param>
        /// <returns>The task object representing the service response for the asynchronous operation.</returns>
        internal Task<ResourceResponse<DocumentCollection>> RestoreDocumentCollectionAsync(string sourceDocumentCollectionLink, DocumentCollection targetDocumentCollection, DateTimeOffset? restoreTime = null, Documents.Client.RequestOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(() => this.RestoreDocumentCollectionPrivateAsync(sourceDocumentCollectionLink, targetDocumentCollection, restoreTime, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<DocumentCollection>> RestoreDocumentCollectionPrivateAsync(string sourceDocumentCollectionLink, DocumentCollection targetDocumentCollection, DateTimeOffset? restoreTime, Documents.Client.RequestOptions options, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(sourceDocumentCollectionLink))
            {
                throw new ArgumentNullException("sourceDocumentCollectionLink");
            }

            if (targetDocumentCollection == null)
            {
                throw new ArgumentNullException("targetDocumentCollection");
            }

            bool isFeed;
            string resourceTypeString;
            string resourceIdOrFullName;
            bool isNameBased;

            string dbsId;
            string databaseLink = PathsHelper.GetDatabasePath(sourceDocumentCollectionLink);
            if (PathsHelper.TryParsePathSegments(databaseLink, out isFeed, out resourceTypeString, out resourceIdOrFullName, out isNameBased) && isNameBased && !isFeed)
            {
                string[] segments = resourceIdOrFullName.Split(new char[] { '/' }, StringSplitOptions.RemoveEmptyEntries);
                dbsId = segments[segments.Length - 1];
            }
            else
            {
                throw new ArgumentNullException("sourceDocumentCollectionLink");
            }

            string sourceCollId;
            if (PathsHelper.TryParsePathSegments(sourceDocumentCollectionLink, out isFeed, out resourceTypeString, out resourceIdOrFullName, out isNameBased) && isNameBased && !isFeed)
            {
                string[] segments = resourceIdOrFullName.Split(new char[] { '/' }, StringSplitOptions.RemoveEmptyEntries);
                sourceCollId = segments[segments.Length - 1];
            }
            else
            {
                throw new ArgumentNullException("sourceDocumentCollectionLink");
            }

            this.ValidateResource(targetDocumentCollection);

            if (options == null)
            {
                options = new Documents.Client.RequestOptions();
            }
            if (!options.RemoteStorageType.HasValue)
            {
                options.RemoteStorageType = RemoteStorageType.Standard;
            }
            options.SourceDatabaseId = dbsId;
            options.SourceCollectionId = sourceCollId;
            if (restoreTime.HasValue)
            {
                options.RestorePointInTime = Helpers.ToUnixTime(restoreTime.Value);
            }

            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Create, ResourceType.Collection);
            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Create,
                databaseLink,
                targetDocumentCollection,
                ResourceType.Collection,
                AuthorizationTokenType.PrimaryMasterKey,
                headers,
                SerializationFormattingPolicy.None))
            {
                ResourceResponse<DocumentCollection> collection = new ResourceResponse<DocumentCollection>(await this.CreateAsync(request, retryPolicyInstance));
                // set the session token
                this.sessionContainer.SetSessionToken(collection.Resource.ResourceId, collection.Resource.AltLink, collection.Headers);
                return collection;
            }
        }

        /// <summary>
        /// Get the status of a collection being restored in the Azure Cosmos DB service.
        /// </summary>
        /// <param name="targetDocumentCollectionLink">The link of the document collection being restored.</param>
        /// <returns>The task object representing the service response for the asynchronous operation.</returns>
        internal Task<DocumentCollectionRestoreStatus> GetDocumentCollectionRestoreStatusAsync(string targetDocumentCollectionLink)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(() => this.GetDocumentCollectionRestoreStatusPrivateAsync(targetDocumentCollectionLink, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<DocumentCollectionRestoreStatus> GetDocumentCollectionRestoreStatusPrivateAsync(string targetDocumentCollectionLink, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            if (string.IsNullOrEmpty(targetDocumentCollectionLink))
            {
                throw new ArgumentNullException("targetDocumentCollectionLink");
            }

            ResourceResponse<DocumentCollection> response = await this.ReadDocumentCollectionPrivateAsync(
                targetDocumentCollectionLink,
                new Documents.Client.RequestOptions { PopulateRestoreStatus = true },
                retryPolicyInstance);
            string restoreState = response.ResponseHeaders.Get(WFConstants.BackendHeaders.RestoreState);
            if (restoreState == null)
            {
                restoreState = RestoreState.RestoreCompleted.ToString();
            }

            DocumentCollectionRestoreStatus ret = new DocumentCollectionRestoreStatus()
            {
                State = restoreState
            };

            return ret;
        }

        /// <summary>
        /// Creates a stored procedure as an asychronous operation in the Azure Cosmos DB service.
        /// </summary>
        /// <param name="collectionLink">The link of the collection to create the stored procedure in. E.g. dbs/db_rid/colls/col_rid/</param>
        /// <param name="storedProcedure">The <see cref="Microsoft.Azure.Documents.StoredProcedure"/> object to create.</param>
        /// <param name="options">(Optional) Any <see cref="Microsoft.Azure.Documents.Client.RequestOptions"/>for this request.</param>
        /// <returns>The <see cref="Microsoft.Azure.Documents.StoredProcedure"/> that was created contained within a <see cref="System.Threading.Tasks.Task"/> object representing the service response for the asynchronous operation.</returns>
        /// <exception cref="ArgumentNullException">If either <paramref name="collectionLink"/> or <paramref name="storedProcedure"/> is not set.</exception>
        /// <exception cref="System.AggregateException">Represents a consolidation of failures that occured during async processing. Look within InnerExceptions to find the actual exception(s)</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>400</term><description>BadRequest - This means something was wrong with the request supplied. It is likely that an Id was not supplied for the stored procedure or the Body was malformed.</description>
        ///     </item>
        ///     <item>
        ///         <term>403</term><description>Forbidden - You have reached your quota of stored procedures for the collection supplied. Contact support to have this quota increased.</description>
        ///     </item>
        ///     <item>
        ///         <term>409</term><description>Conflict - This means a <see cref="Microsoft.Azure.Documents.StoredProcedure"/> with an id matching the id you supplied already existed.</description>
        ///     </item>
        ///     <item>
        ///         <term>413</term><description>RequestEntityTooLarge - This means the body of the <see cref="Microsoft.Azure.Documents.StoredProcedure"/> you tried to create was too large.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        ///
        /// <code language="c#">
        /// <![CDATA[
        /// //Create a new stored procedure called "HelloWorldSproc" that takes in a single param called "name".
        /// StoredProcedure sproc = await client.CreateStoredProcedureAsync(collectionLink, new StoredProcedure
        /// {
        ///    Id = "HelloWorldSproc",
        ///    Body = @"function (name){
        ///                var response = getContext().getResponse();
        ///                response.setBody('Hello ' + name);
        ///             }"
        /// });
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.StoredProcedure"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<ResourceResponse<StoredProcedure>> CreateStoredProcedureAsync(string collectionLink, StoredProcedure storedProcedure, Documents.Client.RequestOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(() => this.CreateStoredProcedurePrivateAsync(collectionLink, storedProcedure, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<StoredProcedure>> CreateStoredProcedurePrivateAsync(
            string collectionLink,
            StoredProcedure storedProcedure,
            Documents.Client.RequestOptions options,
            IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(collectionLink))
            {
                throw new ArgumentNullException("collectionLink");
            }

            if (storedProcedure == null)
            {
                throw new ArgumentNullException("storedProcedure");
            }

            this.ValidateResource(storedProcedure);

            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Create, ResourceType.StoredProcedure);
            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Create,
                collectionLink,
                storedProcedure,
                ResourceType.StoredProcedure,
                AuthorizationTokenType.PrimaryMasterKey,
                headers,
                SerializationFormattingPolicy.None))
            {
                return new ResourceResponse<StoredProcedure>(await this.CreateAsync(request, retryPolicyInstance));
            }
        }

        /// <summary>
        /// Creates a trigger as an asychronous operation in the Azure Cosmos DB service.
        /// </summary>
        /// <param name="collectionLink">The link of the <see cref="Microsoft.Azure.Documents.DocumentCollection"/> to create the trigger in. E.g. dbs/db_rid/colls/col_rid/ </param>
        /// <param name="trigger">The <see cref="Microsoft.Azure.Documents.Trigger"/> object to create.</param>
        /// <param name="options">(Optional) Any <see cref="Microsoft.Azure.Documents.Client.RequestOptions"/>for this request.</param>
        /// <returns>A task object representing the service response for the asynchronous operation.</returns>
        /// <exception cref="ArgumentNullException">If either <paramref name="collectionLink"/> or <paramref name="trigger"/> is not set.</exception>
        /// <exception cref="System.AggregateException">Represents a consolidation of failures that occured during async processing. Look within InnerExceptions to find the actual exception(s)</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>400</term><description>BadRequest - This means something was wrong with the request supplied. It is likely that an Id was not supplied for the new trigger or that the Body was malformed.</description>
        ///     </item>
        ///     <item>
        ///         <term>403</term><description>Forbidden - You have reached your quota of triggers for the collection supplied. Contact support to have this quota increased.</description>
        ///     </item>
        ///     <item>
        ///         <term>409</term><description>Conflict - This means a <see cref="Microsoft.Azure.Documents.Trigger"/> with an id matching the id you supplied already existed.</description>
        ///     </item>
        ///     <item>
        ///         <term>413</term><description>RequestEntityTooLarge - This means the body of the <see cref="Microsoft.Azure.Documents.Trigger"/> you tried to create was too large.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        ///
        /// <code language="c#">
        /// <![CDATA[
        /// //Create a trigger that validates the contents of a document as it is created and adds a 'timestamp' property if one was not found.
        /// Trigger trig = await client.CreateTriggerAsync(collectionLink, new Trigger
        /// {
        ///     Id = "ValidateDocuments",
        ///     Body = @"function validate() {
        ///                         var context = getContext();
        ///                         var request = context.getRequest();                                                             
        ///                         var documentToCreate = request.getBody();
        ///                         
        ///                         // validate properties
        ///                         if (!('timestamp' in documentToCreate)) {
        ///                             var ts = new Date();
        ///                             documentToCreate['timestamp'] = ts.getTime();
        ///                         }
        ///                         
        ///                         // update the document that will be created
        ///                         request.setBody(documentToCreate);
        ///                       }",
        ///     TriggerType = TriggerType.Pre,
        ///     TriggerOperation = TriggerOperation.Create
        /// });
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.Trigger"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<ResourceResponse<Trigger>> CreateTriggerAsync(string collectionLink, Trigger trigger, Documents.Client.RequestOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(() => this.CreateTriggerPrivateAsync(collectionLink, trigger, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<Trigger>> CreateTriggerPrivateAsync(string collectionLink, Trigger trigger, Documents.Client.RequestOptions options, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(collectionLink))
            {
                throw new ArgumentNullException("collectionLink");
            }

            if (trigger == null)
            {
                throw new ArgumentNullException("trigger");
            }

            this.ValidateResource(trigger);
            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Create, ResourceType.Trigger);
            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Create,
                collectionLink,
                trigger,
                ResourceType.Trigger,
                AuthorizationTokenType.PrimaryMasterKey,
                headers,
                SerializationFormattingPolicy.None))
            {
                return new ResourceResponse<Trigger>(await this.CreateAsync(request, retryPolicyInstance));
            }
        }

        /// <summary>
        /// Creates a user defined function as an asychronous operation in the Azure Cosmos DB service.
        /// </summary>
        /// <param name="collectionLink">The link of the <see cref="Microsoft.Azure.Documents.DocumentCollection"/> to create the user defined function in. E.g. dbs/db_rid/colls/col_rid/ </param>
        /// <param name="function">The <see cref="Microsoft.Azure.Documents.UserDefinedFunction"/> object to create.</param>
        /// <param name="options">(Optional) Any <see cref="Microsoft.Azure.Documents.Client.RequestOptions"/>for this request.</param>
        /// <returns>A task object representing the service response for the asynchronous operation.</returns>
        /// <exception cref="ArgumentNullException">If either <paramref name="collectionLink"/> or <paramref name="function"/> is not set.</exception>
        /// <exception cref="System.AggregateException">Represents a consolidation of failures that occured during async processing. Look within InnerExceptions to find the actual exception(s)</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>400</term><description>BadRequest - This means something was wrong with the request supplied. It is likely that an Id was not supplied for the new user defined function or that the Body was malformed.</description>
        ///     </item>
        ///     <item>
        ///         <term>403</term><description>Forbidden - You have reached your quota of user defined functions for the collection supplied. Contact support to have this quota increased.</description>
        ///     </item>
        ///     <item>
        ///         <term>409</term><description>Conflict - This means a <see cref="Microsoft.Azure.Documents.UserDefinedFunction"/> with an id matching the id you supplied already existed.</description>
        ///     </item>
        ///     <item>
        ///         <term>413</term><description>RequestEntityTooLarge - This means the body of the <see cref="Microsoft.Azure.Documents.UserDefinedFunction"/> you tried to create was too large.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        ///
        /// <code language="c#">
        /// <![CDATA[
        /// //Create a user defined function that converts a string to upper case
        /// UserDefinedFunction udf = client.CreateUserDefinedFunctionAsync(collectionLink, new UserDefinedFunction
        /// {
        ///    Id = "ToUpper",
        ///    Body = @"function toUpper(input) {
        ///                        return input.toUpperCase();
        ///                     }",
        /// });
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.UserDefinedFunction"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<ResourceResponse<UserDefinedFunction>> CreateUserDefinedFunctionAsync(string collectionLink, UserDefinedFunction function, Documents.Client.RequestOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(() => this.CreateUserDefinedFunctionPrivateAsync(collectionLink, function, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<UserDefinedFunction>> CreateUserDefinedFunctionPrivateAsync(
            string collectionLink,
            UserDefinedFunction function,
            Documents.Client.RequestOptions options,
            IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(collectionLink))
            {
                throw new ArgumentNullException("collectionLink");
            }

            if (function == null)
            {
                throw new ArgumentNullException("function");
            }

            this.ValidateResource(function);
            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Create, ResourceType.UserDefinedFunction);
            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Create,
                collectionLink,
                function,
                ResourceType.UserDefinedFunction,
                AuthorizationTokenType.PrimaryMasterKey,
                headers,
                SerializationFormattingPolicy.None))
            {
                return new ResourceResponse<UserDefinedFunction>(await this.CreateAsync(request, retryPolicyInstance));
            }
        }

        /// <summary>
        /// Creates a user defined type object as an asychronous operation in the Azure Cosmos DB service.
        /// </summary>
        /// <param name="databaseLink">The link of the database to create the user defined type in. E.g. dbs/db_rid/ </param>
        /// <param name="userDefinedType">The <see cref="Microsoft.Azure.Documents.UserDefinedType"/> object to create.</param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <returns>A task object representing the service response for the asynchronous operation which contains the created <see cref="Microsoft.Azure.Documents.UserDefinedType"/> object.</returns>
        /// <exception cref="ArgumentNullException">If either <paramref name="databaseLink"/> or <paramref name="userDefinedType"/> is not set.</exception>
        /// <exception cref="System.AggregateException">Represents a consolidation of failures that occured during async processing. Look within InnerExceptions to find the actual exception(s)</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a UserDefinedType are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>400</term><description>BadRequest - This means something was wrong with the request supplied.</description>
        ///     </item>
        ///     <item>
        ///         <term>403</term><description>Forbidden - You have reached your quota of user defined type objects for this database. Contact support to have this quota increased.</description>
        ///     </item>
        ///     <item>
        ///         <term>409</term><description>Conflict - This means a <see cref="Microsoft.Azure.Documents.UserDefinedType"/> with an id matching the id you supplied already existed.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        ///
        /// <code language="c#">
        /// <![CDATA[
        /// //Create a new user defined type in the specified database
        /// UserDefinedType userDefinedType = await client.CreateUserDefinedTypeAsync(databaseLink, new UserDefinedType { Id = "userDefinedTypeId5" });
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.UserDefinedType"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        internal Task<ResourceResponse<UserDefinedType>> CreateUserDefinedTypeAsync(string databaseLink, UserDefinedType userDefinedType, Documents.Client.RequestOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(() => this.CreateUserDefinedTypePrivateAsync(databaseLink, userDefinedType, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<UserDefinedType>> CreateUserDefinedTypePrivateAsync(string databaseLink, UserDefinedType userDefinedType, Documents.Client.RequestOptions options, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(databaseLink))
            {
                throw new ArgumentNullException("databaseLink");
            }

            if (userDefinedType == null)
            {
                throw new ArgumentNullException("userDefinedType");
            }

            this.ValidateResource(userDefinedType);
            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Create, ResourceType.UserDefinedType);
            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Create,
                databaseLink,
                userDefinedType,
                ResourceType.UserDefinedType,
                AuthorizationTokenType.PrimaryMasterKey,
                headers,
                SerializationFormattingPolicy.None))
            {
                return new ResourceResponse<UserDefinedType>(await this.CreateAsync(request, retryPolicyInstance));
            }
        }

        /// <summary>
        /// Creates a snapshot resource as an asychronous operation in the Azure Cosmos DB service.
        /// </summary>
        /// <param name="snapshot">The specification for the <see cref="Snapshot"/> to create.</param>
        /// <param name="options">(Optional) The <see cref="Documents.Client.RequestOptions"/> for the request.</param>
        /// <returns>The <see cref="Snapshot"/> that was created within a task object representing the service response for the asynchronous operation.</returns>
        /// <exception cref="ArgumentNullException">If <paramref name="snapshot"/> is not set.</exception>
        /// <exception cref="System.AggregateException">Represents a consolidation of failures that occured during async processing. Look within InnerExceptions to find the actual exception(s).</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Database are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>400</term><description>BadRequest - This means something was wrong with the snapshot object supplied. It is likely that the resource link specified for the Snapshot was invalid.</description>
        ///     </item>
        ///     <item>
        ///         <term>409</term>
        ///         <description>
        ///         Conflict - This means a <see cref="Snapshot"/> with an id matching the id field of <paramref name="snapshot"/> already existed,
        ///         or there is already a pending snapshot for the specified resource link.
        ///         </description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// The example below creates a new <see cref="Snapshot"/> with an Id property of 'MySnapshot'. The ResourceLink indicates that
        /// the snapshot should be created for the collection named "myContainer" in the database "myDatabase".
        /// This code snippet is intended to be used from within an asynchronous method as it uses the await keyword
        /// <code language="c#">
        /// <![CDATA[
        /// using (IDocumentClient client = new DocumentClient(new Uri("service endpoint"), "auth key"))
        /// {
        ///     Snapshot snapshot = await client.CreateSnapshotAsync(new Snapshot { Id = "MySnapshot", ResourceLink = ResourceLink = "dbs/myDatabase/colls/myContainer" });
        /// }
        /// ]]>
        /// </code>
        /// </example>
        /// <example>
        /// If you would like to construct a <see cref="Snapshot"/> from within a synchronous method then you need to use the following code
        /// <code language="c#">
        /// <![CDATA[
        /// using (IDocumentClient client = new DocumentClient(new Uri("service endpoint"), "auth key"))
        /// {
        ///     Snapshot snapshot = client.CreateSnapshotAsync(new Snapshot { Id = "MySnapshot", ResourceLink = ResourceLink = "dbs/myDatabase/colls/myContainer" });.Result;
        /// }
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.Snapshot"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        internal Task<ResourceResponse<Snapshot>> CreateSnapshotAsync(Snapshot snapshot, Documents.Client.RequestOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(() => this.CreateSnapshotPrivateAsync(snapshot, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<Snapshot>> CreateSnapshotPrivateAsync(Snapshot snapshot, Documents.Client.RequestOptions options, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (snapshot == null)
            {
                throw new ArgumentNullException("snapshot");
            }

            this.ValidateResource(snapshot);

            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Create, ResourceType.Snapshot);

            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Create,
                Paths.Snapshots_Root,
                snapshot,
                ResourceType.Snapshot,
                AuthorizationTokenType.PrimaryMasterKey,
                headers,
                SerializationFormattingPolicy.None))
            {
                return new ResourceResponse<Snapshot>(await this.CreateAsync(request, retryPolicyInstance));
            }
        }

        #endregion

        #region Delete Impl
        /// <summary>
        /// Delete a <see cref="Microsoft.Azure.Documents.Database"/> from the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="databaseLink">The link of the <see cref="Microsoft.Azure.Documents.Database"/> to delete. E.g. dbs/db_rid/ </param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <returns>A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which will contain information about the request issued.</returns>
        /// <exception cref="ArgumentNullException">If <paramref name="databaseLink"/> is not set.</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>404</term><description>NotFound - This means the resource you tried to delete did not exist.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// //Delete a database using its selfLink property
        /// //To get the databaseLink you would have to query for the Database, using CreateDatabaseQuery(),  and then refer to its .SelfLink property
        /// await client.DeleteDatabaseAsync(databaseLink);
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.Database"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<ResourceResponse<Documents.Database>> DeleteDatabaseAsync(string databaseLink, Documents.Client.RequestOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(() => this.DeleteDatabasePrivateAsync(databaseLink, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<Documents.Database>> DeleteDatabasePrivateAsync(string databaseLink, Documents.Client.RequestOptions options, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(databaseLink))
            {
                throw new ArgumentNullException("databaseLink");
            }

            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Delete, ResourceType.Database);
            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Delete,
                ResourceType.Database,
                databaseLink,
                AuthorizationTokenType.PrimaryMasterKey,
                headers))
            {
                return new ResourceResponse<Documents.Database>(await this.DeleteAsync(request, retryPolicyInstance));
            }
        }

        /// <summary>
        /// Delete a <see cref="Microsoft.Azure.Documents.Document"/> from the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="documentLink">The link of the <see cref="Microsoft.Azure.Documents.Document"/> to delete. E.g. dbs/db_rid/colls/col_rid/docs/doc_rid/ </param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <param name="cancellationToken">(Optional) A <see cref="CancellationToken"/> that can be used by other objects or threads to receive notice of cancellation.</param>
        /// <returns>A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which will contain information about the request issued.</returns>
        /// <exception cref="ArgumentNullException">If <paramref name="documentLink"/> is not set.</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>404</term><description>NotFound - This means the resource you tried to delete did not exist.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// //Delete a document using its selfLink property
        /// //To get the documentLink you would have to query for the Document, using CreateDocumentQuery(),  and then refer to its .SelfLink property
        /// await client.DeleteDocumentAsync(documentLink);
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.Database"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<ResourceResponse<Document>> DeleteDocumentAsync(string documentLink, Documents.Client.RequestOptions options = null, CancellationToken cancellationToken = default)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(() => this.DeleteDocumentPrivateAsync(documentLink, options, retryPolicyInstance, cancellationToken), retryPolicyInstance, cancellationToken);
        }

        private async Task<ResourceResponse<Document>> DeleteDocumentPrivateAsync(string documentLink, Documents.Client.RequestOptions options, IDocumentClientRetryPolicy retryPolicyInstance, CancellationToken cancellationToken)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(documentLink))
            {
                throw new ArgumentNullException("documentLink");
            }

            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Delete, ResourceType.Document);
            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Delete,
                ResourceType.Document,
                documentLink,
                AuthorizationTokenType.PrimaryMasterKey,
                headers))
            {
                await this.AddPartitionKeyInformationAsync(request, options);
                request.SerializerSettings = this.GetSerializerSettingsForRequest(options);
                return new ResourceResponse<Document>(await this.DeleteAsync(request, retryPolicyInstance, cancellationToken));
            }
        }

        /// <summary>
        /// Delete a <see cref="Microsoft.Azure.Documents.DocumentCollection"/> from the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="documentCollectionLink">The link of the <see cref="Microsoft.Azure.Documents.Document"/> to delete. E.g. dbs/db_rid/colls/col_rid/ </param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <returns>A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which will contain information about the request issued.</returns>
        /// <exception cref="ArgumentNullException">If <paramref name="documentCollectionLink"/> is not set.</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>404</term><description>NotFound - This means the resource you tried to delete did not exist.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// //Delete a collection using its selfLink property
        /// //To get the collectionLink you would have to query for the Collection, using CreateDocumentCollectionQuery(),  and then refer to its .SelfLink property
        /// await client.DeleteDocumentCollectionAsync(collectionLink);
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.DocumentCollection"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<ResourceResponse<DocumentCollection>> DeleteDocumentCollectionAsync(string documentCollectionLink, Documents.Client.RequestOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(() => this.DeleteDocumentCollectionPrivateAsync(documentCollectionLink, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<DocumentCollection>> DeleteDocumentCollectionPrivateAsync(string documentCollectionLink, Documents.Client.RequestOptions options, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(documentCollectionLink))
            {
                throw new ArgumentNullException("documentCollectionLink");
            }

            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Delete, ResourceType.Collection);
            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Delete,
                ResourceType.Collection,
                documentCollectionLink,
                AuthorizationTokenType.PrimaryMasterKey,
                headers))
            {
                return new ResourceResponse<DocumentCollection>(await this.DeleteAsync(request, retryPolicyInstance));
            }
        }

        /// <summary>
        /// Delete a <see cref="Microsoft.Azure.Documents.StoredProcedure"/> from the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="storedProcedureLink">The link of the <see cref="Microsoft.Azure.Documents.StoredProcedure"/> to delete. E.g. dbs/db_rid/colls/col_rid/sprocs/sproc_rid/ </param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <returns>A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which will contain information about the request issued.</returns>
        /// <exception cref="ArgumentNullException">If <paramref name="storedProcedureLink"/> is not set.</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>404</term><description>NotFound - This means the resource you tried to delete did not exist.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// //Delete a stored procedure using its selfLink property.
        /// //To get the sprocLink you would have to query for the Stored Procedure, using CreateStoredProcedureQuery(),  and then refer to its .SelfLink property
        /// await client.DeleteStoredProcedureAsync(sprocLink);
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.StoredProcedure"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<ResourceResponse<StoredProcedure>> DeleteStoredProcedureAsync(string storedProcedureLink, Documents.Client.RequestOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(() => this.DeleteStoredProcedurePrivateAsync(storedProcedureLink, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<StoredProcedure>> DeleteStoredProcedurePrivateAsync(string storedProcedureLink, Documents.Client.RequestOptions options, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(storedProcedureLink))
            {
                throw new ArgumentNullException("storedProcedureLink");
            }

            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Delete, ResourceType.StoredProcedure);
            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Delete,
                ResourceType.StoredProcedure,
                storedProcedureLink,
                AuthorizationTokenType.PrimaryMasterKey,
                headers))
            {
                return new ResourceResponse<StoredProcedure>(await this.DeleteAsync(request, retryPolicyInstance));
            }
        }

        /// <summary>
        /// Delete a <see cref="Microsoft.Azure.Documents.Trigger"/> from the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="triggerLink">The link of the <see cref="Microsoft.Azure.Documents.Trigger"/> to delete. E.g. dbs/db_rid/colls/col_rid/triggers/trigger_rid/ </param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <returns>A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which will contain information about the request issued.</returns>
        /// <exception cref="ArgumentNullException">If <paramref name="triggerLink"/> is not set.</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>404</term><description>NotFound - This means the resource you tried to delete did not exist.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// //Delete a trigger using its selfLink property.
        /// //To get the triggerLink you would have to query for the Trigger, using CreateTriggerQuery(),  and then refer to its .SelfLink property
        /// await client.DeleteTriggerAsync(triggerLink);
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.Trigger"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<ResourceResponse<Trigger>> DeleteTriggerAsync(string triggerLink, Documents.Client.RequestOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(() => this.DeleteTriggerPrivateAsync(triggerLink, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<Trigger>> DeleteTriggerPrivateAsync(string triggerLink, Documents.Client.RequestOptions options, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(triggerLink))
            {
                throw new ArgumentNullException("triggerLink");
            }

            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Delete, ResourceType.Trigger);
            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Delete,
                ResourceType.Trigger,
                triggerLink,
                AuthorizationTokenType.PrimaryMasterKey,
                headers))
            {
                return new ResourceResponse<Trigger>(await this.DeleteAsync(request, retryPolicyInstance));
            }
        }

        /// <summary>
        /// Delete a <see cref="Microsoft.Azure.Documents.UserDefinedFunction"/> from the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="functionLink">The link of the <see cref="Microsoft.Azure.Documents.UserDefinedFunction"/> to delete. E.g. dbs/db_rid/colls/col_rid/udfs/udf_rid/ </param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <returns>A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which will contain information about the request issued.</returns>
        /// <exception cref="ArgumentNullException">If <paramref name="functionLink"/> is not set.</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>404</term><description>NotFound - This means the resource you tried to delete did not exist.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// //Delete a user defined function using its selfLink property.
        /// //To get the functionLink you would have to query for the User Defined Function, using CreateUserDefinedFunctionQuery(),  and then refer to its .SelfLink property
        /// await client.DeleteUserDefinedFunctionAsync(functionLink);
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.UserDefinedFunction"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<ResourceResponse<UserDefinedFunction>> DeleteUserDefinedFunctionAsync(string functionLink, Documents.Client.RequestOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(() => this.DeleteUserDefinedFunctionPrivateAsync(functionLink, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<UserDefinedFunction>> DeleteUserDefinedFunctionPrivateAsync(string functionLink, Documents.Client.RequestOptions options, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(functionLink))
            {
                throw new ArgumentNullException("functionLink");
            }

            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Delete, ResourceType.UserDefinedFunction);
            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Delete,
                ResourceType.UserDefinedFunction,
                functionLink,
                AuthorizationTokenType.PrimaryMasterKey,
                headers))
            {
                return new ResourceResponse<UserDefinedFunction>(await this.DeleteAsync(request, retryPolicyInstance));
            }
        }

        /// <summary>
        /// Delete a <see cref="Microsoft.Azure.Documents.Conflict"/> from the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="conflictLink">The link of the <see cref="Microsoft.Azure.Documents.Conflict"/> to delete. E.g. dbs/db_rid/colls/coll_rid/conflicts/ </param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <returns>A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which will contain information about the request issued.</returns>
        /// <exception cref="ArgumentNullException">If <paramref name="conflictLink"/> is not set.</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>404</term><description>NotFound - This means the resource you tried to delete did not exist.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// //Delete a conflict using its selfLink property.
        /// //To get the conflictLink you would have to query for the Conflict object, using CreateConflictQuery(), and then refer to its .SelfLink property
        /// await client.DeleteConflictAsync(conflictLink);
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.Conflict"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<ResourceResponse<Conflict>> DeleteConflictAsync(string conflictLink, Documents.Client.RequestOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(() => this.DeleteConflictPrivateAsync(conflictLink, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<Conflict>> DeleteConflictPrivateAsync(string conflictLink, Documents.Client.RequestOptions options, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(conflictLink))
            {
                throw new ArgumentNullException("conflictLink");
            }

            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Delete, ResourceType.Conflict);
            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Delete,
                ResourceType.Conflict,
                conflictLink,
                AuthorizationTokenType.PrimaryMasterKey,
                headers))
            {
                await this.AddPartitionKeyInformationAsync(request, options);
                return new ResourceResponse<Conflict>(await this.DeleteAsync(request, retryPolicyInstance));
            }
        }

        /// <summary>
        /// Delete a <see cref="Microsoft.Azure.Documents.Snapshot"/> from the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="snapshotLink">The link of the <see cref="Microsoft.Azure.Documents.Snapshot"/> to delete. E.g. snapshots/snapshot_rid/ </param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <returns>A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which will contain information about the request issued.</returns>
        /// <exception cref="ArgumentNullException">If <paramref name="snapshotLink"/> is not set.</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>404</term><description>NotFound - This means the resource you tried to delete did not exist.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// //Delete a snapshot using its selfLink property
        /// //To get the snapshot you would have to query for the Snapshot, using CreateSnapshotQuery(),  and then refer to its .SelfLink property
        /// await client.DeleteSnapshotAsync(snapshotLink);
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.Snapshot"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        internal Task<ResourceResponse<Snapshot>> DeleteSnapshotAsync(string snapshotLink, Documents.Client.RequestOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(() => this.DeleteSnapshotPrivateAsync(snapshotLink, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<Snapshot>> DeleteSnapshotPrivateAsync(string snapshotLink, Documents.Client.RequestOptions options, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(snapshotLink))
            {
                throw new ArgumentNullException("snapshotLink");
            }

            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Delete, ResourceType.Snapshot);
            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Delete,
                ResourceType.Snapshot,
                snapshotLink,
                AuthorizationTokenType.PrimaryMasterKey,
                headers))
            {
                return new ResourceResponse<Snapshot>(await this.DeleteAsync(request, retryPolicyInstance));
            }
        }

        #endregion

        #region Replace Impl
        /// <summary>
        /// Replaces a document collection in the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="documentCollection">the updated document collection.</param>
        /// <param name="options">the request options for the request.</param>
        /// <returns>
        /// A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which wraps a <see cref="Microsoft.Azure.Documents.DocumentCollection"/> containing the updated resource record.
        /// </returns>
        public Task<ResourceResponse<DocumentCollection>> ReplaceDocumentCollectionAsync(DocumentCollection documentCollection, Documents.Client.RequestOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(() => this.ReplaceDocumentCollectionPrivateAsync(documentCollection, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<DocumentCollection>> ReplaceDocumentCollectionPrivateAsync(
            DocumentCollection documentCollection,
            Documents.Client.RequestOptions options,
            IDocumentClientRetryPolicy retryPolicyInstance,
            string altLink = null)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (documentCollection == null)
            {
                throw new ArgumentNullException("documentCollection");
            }

            this.ValidateResource(documentCollection);
            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Replace, ResourceType.Collection);
            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Replace,
                altLink ?? this.GetLinkForRouting(documentCollection),
                documentCollection,
                ResourceType.Collection,
                AuthorizationTokenType.PrimaryMasterKey,
                headers,
                SerializationFormattingPolicy.None))
            {
                ResourceResponse<DocumentCollection> collection = new ResourceResponse<DocumentCollection>(await this.UpdateAsync(request, retryPolicyInstance));
                // set the session token
                if (collection.Resource != null)
                {
                    this.sessionContainer.SetSessionToken(collection.Resource.ResourceId, collection.Resource.AltLink, collection.Headers);
                }
                return collection;
            }
        }

        /// <summary>
        /// Replaces a <see cref="Microsoft.Azure.Documents.Document"/> in the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="documentLink">The link of the document to be updated. E.g. dbs/db_rid/colls/col_rid/docs/doc_rid/ </param>
        /// <param name="document">The updated <see cref="Microsoft.Azure.Documents.Document"/> to replace the existing resource with.</param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <param name="cancellationToken">(Optional) A <see cref="CancellationToken"/> that can be used by other objects or threads to receive notice of cancellation.</param>
        /// <returns>
        /// A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which wraps a <see cref="Microsoft.Azure.Documents.Document"/> containing the updated resource record.
        /// </returns>
        /// <exception cref="ArgumentNullException">If either <paramref name="documentLink"/> or <paramref name="document"/> is not set.</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>404</term><description>NotFound - This means the resource you tried to delete did not exist.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// In this example, instead of using a strongly typed <see cref="Document"/>, we will work with our own POCO object and not rely on the dynamic nature of the Document class.
        /// <code language="c#">
        /// <![CDATA[
        /// public class MyPoco
        /// {
        ///     public string Id {get; set;}
        ///     public string MyProperty {get; set;}
        /// }
        ///
        /// //Get the doc back as a Document so you have access to doc.SelfLink
        /// Document doc = client.CreateDocumentQuery<Document>(collectionLink)
        ///                        .Where(r => r.Id == "doc id")
        ///                        .AsEnumerable()
        ///                        .SingleOrDefault();
        ///
        /// //Now dynamically cast doc back to your MyPoco
        /// MyPoco poco = (dynamic)doc;
        ///
        /// //Update some properties of the poco object
        /// poco.MyProperty = "updated value";
        ///
        /// //Now persist these changes to the database using doc.SelLink and the update poco object
        /// Document updated = await client.ReplaceDocumentAsync(doc.SelfLink, poco);
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.Document"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<ResourceResponse<Document>> ReplaceDocumentAsync(string documentLink, object document, Documents.Client.RequestOptions options = null, CancellationToken cancellationToken = default)
        {
            // This call is to just run ReplaceDocumentInlineAsync in a SynchronizationContext aware environment
            return TaskHelper.InlineIfPossible(() => this.ReplaceDocumentInlineAsync(documentLink, document, options, cancellationToken), null, cancellationToken);
        }

        private async Task<ResourceResponse<Document>> ReplaceDocumentInlineAsync(string documentLink, object document, Documents.Client.RequestOptions options, CancellationToken cancellationToken)
        {
            IDocumentClientRetryPolicy requestRetryPolicy = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            if ((options == null) || (options.PartitionKey == null))
            {
                requestRetryPolicy = new PartitionKeyMismatchRetryPolicy(
                    await this.GetCollectionCacheAsync(NoOpTrace.Singleton), 
                    requestRetryPolicy);
            }

            return await TaskHelper.InlineIfPossible(
                () => this.ReplaceDocumentPrivateAsync(
                    documentLink, 
                    document, 
                    options, 
                    requestRetryPolicy, 
                    cancellationToken), 
                requestRetryPolicy, 
                cancellationToken);
        }

        private Task<ResourceResponse<Document>> ReplaceDocumentPrivateAsync(string documentLink, object document, Documents.Client.RequestOptions options, IDocumentClientRetryPolicy retryPolicyInstance, CancellationToken cancellationToken)
        {
            if (string.IsNullOrEmpty(documentLink))
            {
                throw new ArgumentNullException("documentLink");
            }

            if (document == null)
            {
                throw new ArgumentNullException("document");
            }

            Document typedDocument = Document.FromObject(document, this.GetSerializerSettingsForRequest(options));
            this.ValidateResource(typedDocument);
            return this.ReplaceDocumentPrivateAsync(documentLink, typedDocument, options, retryPolicyInstance, cancellationToken);
        }

        /// <summary>
        /// Replaces a <see cref="Microsoft.Azure.Documents.Document"/> in the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="document">The updated <see cref="Microsoft.Azure.Documents.Document"/> to replace the existing resource with.</param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <param name="cancellationToken">(Optional) A <see cref="CancellationToken"/> that can be used by other objects or threads to receive notice of cancellation.</param>
        /// <returns>
        /// A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which wraps a <see cref="Microsoft.Azure.Documents.Document"/> containing the updated resource record.
        /// </returns>
        /// <exception cref="ArgumentNullException">If <paramref name="document"/> is not set.</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>404</term><description>NotFound - This means the resource you tried to delete did not exist.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// This example uses <see cref="Document"/> and takes advantage of the fact that it is a dynamic object and uses SetProperty to dynamically update properties on the document
        /// <code language="c#">
        /// <![CDATA[
        /// //Fetch the Document to be updated
        /// Document doc = client.CreateDocumentQuery<Document>(collectionLink)
        ///                             .Where(r => r.Id == "doc id")
        ///                             .AsEnumerable()
        ///                             .SingleOrDefault();
        ///
        /// //Update some properties on the found resource
        /// doc.SetPropertyValue("MyProperty", "updated value");
        ///
        /// //Now persist these changes to the database by replacing the original resource
        /// Document updated = await client.ReplaceDocumentAsync(doc);
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.Document"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<ResourceResponse<Document>> ReplaceDocumentAsync(Document document, Documents.Client.RequestOptions options = null, CancellationToken cancellationToken = default)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(() => this.ReplaceDocumentPrivateAsync(
                this.GetLinkForRouting(document),
                document,
                options,
                retryPolicyInstance,
                cancellationToken),
                retryPolicyInstance,
                cancellationToken);
        }

        private async Task<ResourceResponse<Document>> ReplaceDocumentPrivateAsync(string documentLink, Document document, Documents.Client.RequestOptions options, IDocumentClientRetryPolicy retryPolicyInstance, CancellationToken cancellationToken)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (document == null)
            {
                throw new ArgumentNullException("document");
            }

            this.ValidateResource(document);
            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Replace, ResourceType.Document);
            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Replace,
                documentLink,
                document,
                ResourceType.Document,
                AuthorizationTokenType.PrimaryMasterKey,
                headers,
                SerializationFormattingPolicy.None,
                this.GetSerializerSettingsForRequest(options)))
            {
                await this.AddPartitionKeyInformationAsync(request, document, options);
                return new ResourceResponse<Document>(await this.UpdateAsync(request, retryPolicyInstance, cancellationToken));
            }
        }

        /// <summary>
        /// Replaces a <see cref="Microsoft.Azure.Documents.StoredProcedure"/> in the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="storedProcedure">The updated <see cref="Microsoft.Azure.Documents.StoredProcedure"/> to replace the existing resource with.</param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <returns>
        /// A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which wraps a <see cref="Microsoft.Azure.Documents.StoredProcedure"/> containing the updated resource record.
        /// </returns>
        /// <exception cref="ArgumentNullException">If <paramref name="storedProcedure"/> is not set.</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>404</term><description>NotFound - This means the resource you tried to delete did not exist.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// //Fetch the resource to be updated
        /// StoredProcedure sproc = client.CreateStoredProcedureQuery(sprocsLink)
        ///                                  .Where(r => r.Id == "sproc id")
        ///                                  .AsEnumerable()
        ///                                  .SingleOrDefault();
        ///
        /// //Update some properties on the found resource
        /// sproc.Body = "function () {new javascript body for sproc}";
        ///
        /// //Now persist these changes to the database by replacing the original resource
        /// StoredProcedure updated = await client.ReplaceStoredProcedureAsync(sproc);
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.StoredProcedure"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<ResourceResponse<StoredProcedure>> ReplaceStoredProcedureAsync(StoredProcedure storedProcedure, Documents.Client.RequestOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(() => this.ReplaceStoredProcedurePrivateAsync(storedProcedure, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<StoredProcedure>> ReplaceStoredProcedurePrivateAsync(
            StoredProcedure storedProcedure,
            Documents.Client.RequestOptions options,
            IDocumentClientRetryPolicy retryPolicyInstance,
            string altLink = null)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (storedProcedure == null)
            {
                throw new ArgumentNullException("storedProcedure");
            }

            this.ValidateResource(storedProcedure);
            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Replace, ResourceType.StoredProcedure);
            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Replace,
                altLink ?? this.GetLinkForRouting(storedProcedure),
                storedProcedure,
                ResourceType.StoredProcedure,
                AuthorizationTokenType.PrimaryMasterKey,
                headers,
                SerializationFormattingPolicy.None))
            {
                return new ResourceResponse<StoredProcedure>(await this.UpdateAsync(request, retryPolicyInstance));
            }
        }

        /// <summary>
        /// Replaces a <see cref="Microsoft.Azure.Documents.Trigger"/> in the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="trigger">The updated <see cref="Microsoft.Azure.Documents.Trigger"/> to replace the existing resource with.</param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <returns>
        /// A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which wraps a <see cref="Microsoft.Azure.Documents.Trigger"/> containing the updated resource record.
        /// </returns>
        /// <exception cref="ArgumentNullException">If <paramref name="trigger"/> is not set.</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>404</term><description>NotFound - This means the resource you tried to delete did not exist.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// //Fetch the resource to be updated
        /// Trigger trigger = client.CreateTriggerQuery(sprocsLink)
        ///                               .Where(r => r.Id == "trigger id")
        ///                               .AsEnumerable()
        ///                               .SingleOrDefault();
        ///
        /// //Update some properties on the found resource
        /// trigger.Body = "function () {new javascript body for trigger}";
        ///
        /// //Now persist these changes to the database by replacing the original resource
        /// Trigger updated = await client.ReplaceTriggerAsync(sproc);
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.Trigger"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<ResourceResponse<Trigger>> ReplaceTriggerAsync(Trigger trigger, Documents.Client.RequestOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(() => this.ReplaceTriggerPrivateAsync(trigger, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<Trigger>> ReplaceTriggerPrivateAsync(Trigger trigger, Documents.Client.RequestOptions options, IDocumentClientRetryPolicy retryPolicyInstance, string altLink = null)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (trigger == null)
            {
                throw new ArgumentNullException("trigger");
            }

            this.ValidateResource(trigger);
            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Replace, ResourceType.Trigger);
            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Replace,
                altLink ?? this.GetLinkForRouting(trigger),
                trigger,
                ResourceType.Trigger,
                AuthorizationTokenType.PrimaryMasterKey,
                headers,
                SerializationFormattingPolicy.None))
            {
                return new ResourceResponse<Trigger>(await this.UpdateAsync(request, retryPolicyInstance));
            }
        }

        /// <summary>
        /// Replaces a <see cref="Microsoft.Azure.Documents.UserDefinedFunction"/> in the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="function">The updated <see cref="Microsoft.Azure.Documents.UserDefinedFunction"/> to replace the existing resource with.</param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <returns>
        /// A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which wraps a <see cref="Microsoft.Azure.Documents.UserDefinedFunction"/> containing the updated resource record.
        /// </returns>
        /// <exception cref="ArgumentNullException">If <paramref name="function"/> is not set.</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>404</term><description>NotFound - This means the resource you tried to delete did not exist.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// //Fetch the resource to be updated
        /// UserDefinedFunction udf = client.CreateUserDefinedFunctionQuery(functionsLink)
        ///                                     .Where(r => r.Id == "udf id")
        ///                                     .AsEnumerable()
        ///                                     .SingleOrDefault();
        ///
        /// //Update some properties on the found resource
        /// udf.Body = "function () {new javascript body for udf}";
        ///
        /// //Now persist these changes to the database by replacing the original resource
        /// UserDefinedFunction updated = await client.ReplaceUserDefinedFunctionAsync(udf);
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.UserDefinedFunction"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<ResourceResponse<UserDefinedFunction>> ReplaceUserDefinedFunctionAsync(UserDefinedFunction function, Documents.Client.RequestOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(() => this.ReplaceUserDefinedFunctionPrivateAsync(function, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<UserDefinedFunction>> ReplaceUserDefinedFunctionPrivateAsync(
            UserDefinedFunction function,
            Documents.Client.RequestOptions options,
            IDocumentClientRetryPolicy retryPolicyInstance,
            string altLink = null)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (function == null)
            {
                throw new ArgumentNullException("function");
            }

            this.ValidateResource(function);
            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Replace, ResourceType.UserDefinedFunction);
            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Replace,
                altLink ?? this.GetLinkForRouting(function),
                function,
                ResourceType.UserDefinedFunction,
                AuthorizationTokenType.PrimaryMasterKey,
                headers,
                SerializationFormattingPolicy.None))
            {
                return new ResourceResponse<UserDefinedFunction>(await this.UpdateAsync(request, retryPolicyInstance));
            }
        }

        /// <summary>
        /// Replaces a <see cref="Microsoft.Azure.Documents.Offer"/> in the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="offer">The updated <see cref="Microsoft.Azure.Documents.Offer"/> to replace the existing resource with.</param>
        /// <returns>
        /// A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which wraps a <see cref="Microsoft.Azure.Documents.Offer"/> containing the updated resource record.
        /// </returns>
        /// <exception cref="ArgumentNullException">If <paramref name="offer"/> is not set.</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>404</term><description>NotFound - This means the resource you tried to delete did not exist.</description>
        ///     </item>
        ///     <item>
        ///        <term>429</term><description>TooManyRequests - The replace offer is throttled as the offer scale down operation is attempted within the idle timeout period of 4 hours. Consult the DocumentClientException.RetryAfter value to see how long you should wait before retrying this operation.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// //Fetch the resource to be updated
        /// Offer offer = client.CreateOfferQuery()
        ///                          .Where(r => r.ResourceLink == "collection selfLink")
        ///                          .AsEnumerable()
        ///                          .SingleOrDefault();
        ///
        /// //Create a new offer with the changed throughput
        /// OfferV2 newOffer = new OfferV2(offer, 5000);
        ///
        /// //Now persist these changes to the database by replacing the original resource
        /// Offer updated = await client.ReplaceOfferAsync(newOffer);
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.Offer"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<ResourceResponse<Offer>> ReplaceOfferAsync(Offer offer)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(() => this.ReplaceOfferPrivateAsync(offer, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<Offer>> ReplaceOfferPrivateAsync(Offer offer, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            if (offer == null)
            {
                throw new ArgumentNullException("offer");
            }

            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Replace,
                offer.SelfLink,
                offer,
                ResourceType.Offer,
                AuthorizationTokenType.PrimaryMasterKey))
            {
                return new ResourceResponse<Offer>(
                    await this.UpdateAsync(request, retryPolicyInstance),
                    OfferTypeResolver.ResponseOfferTypeResolver);
            }
        }

        /// <summary>
        /// Replaces a <see cref="Microsoft.Azure.Documents.UserDefinedType"/> in the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="userDefinedType">The updated <see cref="Microsoft.Azure.Documents.UserDefinedType"/> to replace the existing resource with.</param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <returns>
        /// A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which wraps a <see cref="Microsoft.Azure.Documents.UserDefinedType"/> containing the updated resource record.
        /// </returns>
        /// <exception cref="ArgumentNullException">If <paramref name="userDefinedType"/> is not set.</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>404</term><description>NotFound - This means the resource you tried to delete did not exist.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// //Fetch the resource to be updated
        /// UserDefinedType userDefinedType = client.CreateUserDefinedTypeQuery(userDefinedTypesLink)
        ///                          .Where(r => r.Id == "user defined type id")
        ///                          .AsEnumerable()
        ///                          .SingleOrDefault();
        ///
        /// //Now persist these changes to the database by replacing the original resource
        /// UserDefinedType updated = await client.ReplaceUserDefinedTypeAsync(userDefinedType);
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.UserDefinedType"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        internal Task<ResourceResponse<UserDefinedType>> ReplaceUserDefinedTypeAsync(UserDefinedType userDefinedType, Documents.Client.RequestOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(() => this.ReplaceUserDefinedTypePrivateAsync(userDefinedType, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<UserDefinedType>> ReplaceUserDefinedTypePrivateAsync(UserDefinedType userDefinedType, Documents.Client.RequestOptions options, IDocumentClientRetryPolicy retryPolicyInstance, string altLink = null)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (userDefinedType == null)
            {
                throw new ArgumentNullException("userDefinedType");
            }

            this.ValidateResource(userDefinedType);
            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Replace, ResourceType.UserDefinedType);
            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Replace,
                altLink ?? this.GetLinkForRouting(userDefinedType),
                userDefinedType,
                ResourceType.UserDefinedType,
                AuthorizationTokenType.PrimaryMasterKey,
                headers,
                SerializationFormattingPolicy.None))
            {
                return new ResourceResponse<UserDefinedType>(await this.UpdateAsync(request, retryPolicyInstance));
            }
        }

        #endregion

        #region Read Impl
        /// <summary>
        /// Reads a <see cref="Microsoft.Azure.Documents.Database"/> from the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="databaseLink">The link of the Database resource to be read.</param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <returns>
        /// A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which wraps a <see cref="Microsoft.Azure.Documents.Database"/> containing the read resource record.
        /// </returns>
        /// <exception cref="ArgumentNullException">If <paramref name="databaseLink"/> is not set.</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>404</term><description>NotFound - This means the resource you tried to read did not exist.</description>
        ///     </item>
        ///     <item>
        ///         <term>429</term><description>TooManyRequests - This means you have exceeded the number of request units per second. Consult the DocumentClientException.RetryAfter value to see how long you should wait before retrying this operation.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// //Reads a Database resource where
        /// // - database_id is the ID property of the Database resource you wish to read.
        /// var dbLink = "/dbs/database_id";
        /// Database database = await client.ReadDatabaseAsync(dbLink);
        /// ]]>
        /// </code>
        /// </example>
        /// <remarks>
        /// <para>
        /// Doing a read of a resource is the most efficient way to get a resource from the Database. If you know the resource's ID, do a read instead of a query by ID.
        /// </para>
        /// <para>
        /// The example shown uses ID-based links, where the link is composed of the ID properties used when the resources were created.
        /// You can still use the <see cref="Microsoft.Azure.Documents.Resource.SelfLink"/> property of the Database if you prefer. A self-link is a URI for a resource that is made up of Resource Identifiers  (or the _rid properties).
        /// ID-based links and SelfLink will both work.
        /// The format for <paramref name="databaseLink"/> is always "/dbs/{db identifier}" only
        /// the values within the {} change depending on which method you wish to use to address the resource.
        /// </para>
        /// </remarks>
        /// <seealso cref="Microsoft.Azure.Documents.Database"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        /// <seealso cref="System.Uri"/>
        public Task<ResourceResponse<Documents.Database>> ReadDatabaseAsync(string databaseLink, Documents.Client.RequestOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(() => this.ReadDatabasePrivateAsync(databaseLink, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<Documents.Database>> ReadDatabasePrivateAsync(string databaseLink, Documents.Client.RequestOptions options, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(databaseLink))
            {
                throw new ArgumentNullException("databaseLink");
            }

            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Read, ResourceType.Database);
            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Read,
                ResourceType.Database,
                databaseLink,
                AuthorizationTokenType.PrimaryMasterKey,
                headers))
            {
                return new ResourceResponse<Documents.Database>(await this.ReadAsync(request, retryPolicyInstance));
            }
        }

        /// <summary>
        /// Reads a <see cref="Microsoft.Azure.Documents.Document"/> from the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="documentLink">The link for the document to be read.</param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <param name="cancellationToken">(Optional) A <see cref="CancellationToken"/> that can be used by other objects or threads to receive notice of cancellation.</param>
        /// <returns>
        /// A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which wraps a <see cref="Microsoft.Azure.Documents.Document"/> containing the read resource record.
        /// </returns>
        /// <exception cref="ArgumentNullException">If <paramref name="documentLink"/> is not set.</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>404</term><description>NotFound - This means the resource you tried to read did not exist.</description>
        ///     </item>
        ///     <item>
        ///         <term>429</term><description>TooManyRequests - This means you have exceeded the number of request units per second. Consult the DocumentClientException.RetryAfter value to see how long you should wait before retrying this operation.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// //This reads a document record from a database & collection where
        /// // - sample_database is the ID of the database
        /// // - sample_collection is the ID of the collection
        /// // - document_id is the ID of the document resource
        /// var docLink = "dbs/sample_database/colls/sample_collection/docs/document_id";
        /// Document doc = await client.ReadDocumentAsync(docLink);
        /// ]]>
        /// </code>
        /// </example>
        /// <remarks>
        /// <para>
        /// Doing a read of a resource is the most efficient way to get a resource from the Database. If you know the resource's ID, do a read instead of a query by ID.
        /// </para>
        /// <para>
        /// The example shown uses ID-based links, where the link is composed of the ID properties used when the resources were created.
        /// You can still use the <see cref="Microsoft.Azure.Documents.Resource.SelfLink"/> property of the Document if you prefer. A self-link is a URI for a resource that is made up of Resource Identifiers  (or the _rid properties).
        /// ID-based links and SelfLink will both work.
        /// The format for <paramref name="documentLink"/> is always "dbs/{db identifier}/colls/{coll identifier}/docs/{doc identifier}" only
        /// the values within the {} change depending on which method you wish to use to address the resource.
        /// </para>
        /// </remarks>
        /// <seealso cref="Microsoft.Azure.Documents.Document"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        /// <seealso cref="System.Uri"/>
        public Task<ResourceResponse<Document>> ReadDocumentAsync(string documentLink, Documents.Client.RequestOptions options = null, CancellationToken cancellationToken = default)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(
                () => this.ReadDocumentPrivateAsync(documentLink, options, retryPolicyInstance, cancellationToken), retryPolicyInstance, cancellationToken);
        }

        private async Task<ResourceResponse<Document>> ReadDocumentPrivateAsync(string documentLink, Documents.Client.RequestOptions options, IDocumentClientRetryPolicy retryPolicyInstance, CancellationToken cancellationToken)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(documentLink))
            {
                throw new ArgumentNullException("documentLink");
            }

            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Read, ResourceType.Document);
            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Read,
                ResourceType.Document,
                documentLink,
                AuthorizationTokenType.PrimaryMasterKey,
                headers))
            {
                await this.AddPartitionKeyInformationAsync(request, options);
                request.SerializerSettings = this.GetSerializerSettingsForRequest(options);
                return new ResourceResponse<Document>(await this.ReadAsync(request, retryPolicyInstance, cancellationToken));
            }
        }

        /// <summary>
        /// Reads a <see cref="Microsoft.Azure.Documents.Document"/> as a generic type T from the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="documentLink">The link for the document to be read.</param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <param name="cancellationToken">(Optional) A <see cref="CancellationToken"/> that can be used by other objects or threads to receive notice of cancellation.</param>
        /// <returns>
        /// A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.DocumentResponse{T}"/> which wraps a <see cref="Microsoft.Azure.Documents.Document"/> containing the read resource record.
        /// </returns>
        /// <exception cref="ArgumentNullException">If <paramref name="documentLink"/> is not set.</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>404</term><description>NotFound - This means the resource you tried to read did not exist.</description>
        ///     </item>
        ///     <item>
        ///         <term>429</term><description>TooManyRequests - This means you have exceeded the number of request units per second. Consult the DocumentClientException.RetryAfter value to see how long you should wait before retrying this operation.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// //This reads a document record from a database & collection where
        /// // - sample_database is the ID of the database
        /// // - sample_collection is the ID of the collection
        /// // - document_id is the ID of the document resource
        /// var docLink = "dbs/sample_database/colls/sample_collection/docs/document_id";
        /// Customer customer = await client.ReadDocumentAsync<Customer>(docLink);
        /// ]]>
        /// </code>
        /// </example>
        /// <remarks>
        /// <para>
        /// Doing a read of a resource is the most efficient way to get a resource from the Database. If you know the resource's ID, do a read instead of a query by ID.
        /// </para>
        /// <para>
        /// The example shown uses ID-based links, where the link is composed of the ID properties used when the resources were created.
        /// You can still use the <see cref="Microsoft.Azure.Documents.Resource.SelfLink"/> property of the Document if you prefer. A self-link is a URI for a resource that is made up of Resource Identifiers  (or the _rid properties).
        /// ID-based links and SelfLink will both work.
        /// The format for <paramref name="documentLink"/> is always "dbs/{db identifier}/colls/{coll identifier}/docs/{doc identifier}" only
        /// the values within the {} change depending on which method you wish to use to address the resource.
        /// </para>
        /// </remarks>
        /// <seealso cref="Microsoft.Azure.Documents.Document"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.DocumentResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        /// <seealso cref="System.Uri"/>
        public Task<DocumentResponse<T>> ReadDocumentAsync<T>(string documentLink, Documents.Client.RequestOptions options = null, CancellationToken cancellationToken = default)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(
                () => this.ReadDocumentPrivateAsync<T>(documentLink, options, retryPolicyInstance, cancellationToken), retryPolicyInstance, cancellationToken);
        }

        private async Task<DocumentResponse<T>> ReadDocumentPrivateAsync<T>(string documentLink, Documents.Client.RequestOptions options, IDocumentClientRetryPolicy retryPolicyInstance, CancellationToken cancellationToken)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(documentLink))
            {
                throw new ArgumentNullException("documentLink");
            }

            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Read, ResourceType.Document);
            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Read,
                ResourceType.Document,
                documentLink,
                AuthorizationTokenType.PrimaryMasterKey,
                headers))
            {
                await this.AddPartitionKeyInformationAsync(request, options);
                request.SerializerSettings = this.GetSerializerSettingsForRequest(options);
                return new DocumentResponse<T>(await this.ReadAsync(request, retryPolicyInstance, cancellationToken), this.GetSerializerSettingsForRequest(options));
            }
        }

        /// <summary>
        /// Reads a <see cref="Microsoft.Azure.Documents.DocumentCollection"/> from the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="documentCollectionLink">The link for the DocumentCollection to be read.</param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <returns>
        /// A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which wraps a <see cref="Microsoft.Azure.Documents.DocumentCollection"/> containing the read resource record.
        /// </returns>
        /// <exception cref="ArgumentNullException">If <paramref name="documentCollectionLink"/> is not set.</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>404</term><description>NotFound - This means the resource you tried to read did not exist.</description>
        ///     </item>
        ///     <item>
        ///         <term>429</term><description>TooManyRequests - This means you have exceeded the number of request units per second. Consult the DocumentClientException.RetryAfter value to see how long you should wait before retrying this operation.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// //This reads a DocumentCollection record from a database where
        /// // - sample_database is the ID of the database
        /// // - collection_id is the ID of the collection resource to be read
        /// var collLink = "/dbs/sample_database/colls/collection_id";
        /// DocumentCollection coll = await client.ReadDocumentCollectionAsync(collLink);
        /// ]]>
        /// </code>
        /// </example>
        /// <remarks>
        /// <para>
        /// Doing a read of a resource is the most efficient way to get a resource from the Database. If you know the resource's ID, do a read instead of a query by ID.
        /// </para>
        /// <para>
        /// The example shown uses ID-based links, where the link is composed of the ID properties used when the resources were created.
        /// You can still use the <see cref="Microsoft.Azure.Documents.Resource.SelfLink"/> property of the DocumentCollection if you prefer. A self-link is a URI for a resource that is made up of Resource Identifiers  (or the _rid properties).
        /// ID-based links and SelfLink will both work.
        /// The format for <paramref name="documentCollectionLink"/> is always "/dbs/{db identifier}/colls/{coll identifier}" only
        /// the values within the {} change depending on which method you wish to use to address the resource.
        /// </para>
        /// </remarks>
        /// <seealso cref="Microsoft.Azure.Documents.DocumentCollection"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        /// <seealso cref="System.Uri"/>
        public Task<ResourceResponse<DocumentCollection>> ReadDocumentCollectionAsync(string documentCollectionLink, Documents.Client.RequestOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(
                () => this.ReadDocumentCollectionPrivateAsync(documentCollectionLink, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<DocumentCollection>> ReadDocumentCollectionPrivateAsync(
            string documentCollectionLink,
            Documents.Client.RequestOptions options,
            IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(documentCollectionLink))
            {
                throw new ArgumentNullException("documentCollectionLink");
            }

            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Read, ResourceType.Collection);
            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Read,
                ResourceType.Collection,
                documentCollectionLink,
                AuthorizationTokenType.PrimaryMasterKey,
                headers))
            {
                return new ResourceResponse<DocumentCollection>(await this.ReadAsync(request, retryPolicyInstance));
            }
        }

        /// <summary>
        /// Reads a <see cref="Microsoft.Azure.Documents.StoredProcedure"/> from the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="storedProcedureLink">The link of the stored procedure to be read.</param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <returns>
        /// A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which wraps a <see cref="Microsoft.Azure.Documents.StoredProcedure"/> containing the read resource record.
        /// </returns>
        /// <exception cref="ArgumentNullException">If <paramref name="storedProcedureLink"/> is not set.</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>404</term><description>NotFound - This means the resource you tried to read did not exist.</description>
        ///     </item>
        ///     <item>
        ///         <term>429</term><description>TooManyRequests - This means you have exceeded the number of request units per second. Consult the DocumentClientException.RetryAfter value to see how long you should wait before retrying this operation.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// //Reads a StoredProcedure from a Database and DocumentCollection where
        /// // - sample_database is the ID of the database
        /// // - sample_collection is the ID of the collection
        /// // - sproc_id is the ID of the stored procedure to be read
        /// var sprocLink = "/dbs/sample_database/colls/sample_collection/sprocs/sproc_id";
        /// StoredProcedure sproc = await client.ReadStoredProcedureAsync(sprocLink);
        /// ]]>
        /// </code>
        /// </example>
        /// <remarks>
        /// <para>
        /// Doing a read of a resource is the most efficient way to get a resource from the Database. If you know the resource's ID, do a read instead of a query by ID.
        /// </para>
        /// <para>
        /// The example shown uses ID-based links, where the link is composed of the ID properties used when the resources were created.
        /// You can still use the <see cref="Microsoft.Azure.Documents.Resource.SelfLink"/> property of the Stored Procedure if you prefer. A self-link is a URI for a resource that is made up of Resource Identifiers  (or the _rid properties).
        /// ID-based links and SelfLink will both work.
        /// The format for <paramref name="storedProcedureLink"/> is always "/dbs/{db identifier}/colls/{coll identifier}/sprocs/{sproc identifier}"
        /// only the values within the {...} change depending on which method you wish to use to address the resource.
        /// </para>
        /// </remarks>
        /// <seealso cref="Microsoft.Azure.Documents.StoredProcedure"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        /// <seealso cref="System.Uri"/>
        public Task<ResourceResponse<StoredProcedure>> ReadStoredProcedureAsync(string storedProcedureLink, Documents.Client.RequestOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(
                () => this.ReadStoredProcedureAsync(storedProcedureLink, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<StoredProcedure>> ReadStoredProcedureAsync(string storedProcedureLink, Documents.Client.RequestOptions options, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(storedProcedureLink))
            {
                throw new ArgumentNullException("storedProcedureLink");
            }

            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Read, ResourceType.StoredProcedure);
            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Read,
                ResourceType.StoredProcedure,
                storedProcedureLink,
                AuthorizationTokenType.PrimaryMasterKey,
                headers))
            {
                return new ResourceResponse<StoredProcedure>(await this.ReadAsync(request, retryPolicyInstance));
            }
        }

        /// <summary>
        /// Reads a <see cref="Microsoft.Azure.Documents.Trigger"/> from the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="triggerLink">The link to the Trigger to be read.</param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <returns>
        /// A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which wraps a <see cref="Microsoft.Azure.Documents.Trigger"/> containing the read resource record.
        /// </returns>
        /// <exception cref="ArgumentNullException">If <paramref name="triggerLink"/> is not set.</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>404</term><description>NotFound - This means the resource you tried to read did not exist.</description>
        ///     </item>
        ///     <item>
        ///         <term>429</term><description>TooManyRequests - This means you have exceeded the number of request units per second. Consult the DocumentClientException.RetryAfter value to see how long you should wait before retrying this operation.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// //Reads a Trigger from a Database and DocumentCollection where
        /// // - sample_database is the ID of the database
        /// // - sample_collection is the ID of the collection
        /// // - trigger_id is the ID of the trigger to be read
        /// var triggerLink = "/dbs/sample_database/colls/sample_collection/triggers/trigger_id";
        /// Trigger trigger = await client.ReadTriggerAsync(triggerLink);
        /// ]]>
        /// </code>
        /// </example>
        /// <remarks>
        /// <para>
        /// Doing a read of a resource is the most efficient way to get a resource from the Database. If you know the resource's ID, do a read instead of a query by ID.
        /// </para>
        /// <para>
        /// The example shown uses ID-based links, where the link is composed of the ID properties used when the resources were created.
        /// You can still use the <see cref="Microsoft.Azure.Documents.Resource.SelfLink"/> property of the Trigger if you prefer. A self-link is a URI for a resource that is made up of Resource Identifiers  (or the _rid properties).
        /// ID-based links and SelfLink will both work.
        /// The format for <paramref name="triggerLink"/> is always "/dbs/{db identifier}/colls/{coll identifier}/triggers/{trigger identifier}"
        /// only the values within the {...} change depending on which method you wish to use to address the resource.
        /// </para>
        /// </remarks>
        /// <seealso cref="Microsoft.Azure.Documents.Trigger"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        /// <seealso cref="System.Uri"/>
        public Task<ResourceResponse<Trigger>> ReadTriggerAsync(string triggerLink, Documents.Client.RequestOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(
                () => this.ReadTriggerPrivateAsync(triggerLink, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<Trigger>> ReadTriggerPrivateAsync(string triggerLink, Documents.Client.RequestOptions options, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(triggerLink))
            {
                throw new ArgumentNullException("triggerLink");
            }

            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Read, ResourceType.Trigger);
            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Read,
                ResourceType.Trigger,
                triggerLink,
                AuthorizationTokenType.PrimaryMasterKey,
                headers))
            {
                return new ResourceResponse<Trigger>(await this.ReadAsync(request, retryPolicyInstance));
            }
        }

        /// <summary>
        /// Reads a <see cref="Microsoft.Azure.Documents.UserDefinedFunction"/> from the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="functionLink">The link to the User Defined Function to be read.</param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <returns>
        /// A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which wraps a <see cref="Microsoft.Azure.Documents.UserDefinedFunction"/> containing the read resource record.
        /// </returns>
        /// <exception cref="ArgumentNullException">If <paramref name="functionLink"/> is not set.</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>404</term><description>NotFound - This means the resource you tried to read did not exist.</description>
        ///     </item>
        ///     <item>
        ///         <term>429</term><description>TooManyRequests - This means you have exceeded the number of request units per second. Consult the DocumentClientException.RetryAfter value to see how long you should wait before retrying this operation.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// //Reads a User Defined Function from a Database and DocumentCollection where
        /// // - sample_database is the ID of the database
        /// // - sample_collection is the ID of the collection
        /// // - udf_id is the ID of the user-defined function to be read
        /// var udfLink = "/dbs/sample_database/colls/sample_collection/udfs/udf_id";
        /// UserDefinedFunction udf = await client.ReadUserDefinedFunctionAsync(udfLink);
        /// ]]>
        /// </code>
        /// </example>
        /// <remarks>
        /// <para>
        /// Doing a read of a resource is the most efficient way to get a resource from the Database. If you know the resource's ID, do a read instead of a query by ID.
        /// </para>
        /// <para>
        /// The example shown uses ID-based links, where the link is composed of the ID properties used when the resources were created.
        /// You can still use the <see cref="Microsoft.Azure.Documents.Resource.SelfLink"/> property of the User Defined Function if you prefer. A self-link is a URI for a resource that is made up of Resource Identifiers  (or the _rid properties).
        /// ID-based links and SelfLink will both work.
        /// The format for <paramref name="functionLink"/> is always "/dbs/{db identifier}/colls/{coll identifier}/udfs/{udf identifier}"
        /// only the values within the {...} change depending on which method you wish to use to address the resource.
        /// </para>
        /// </remarks>
        /// <seealso cref="Microsoft.Azure.Documents.UserDefinedFunction"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        /// <seealso cref="System.Uri"/>
        public Task<ResourceResponse<UserDefinedFunction>> ReadUserDefinedFunctionAsync(string functionLink, Documents.Client.RequestOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(
                () => this.ReadUserDefinedFunctionPrivateAsync(functionLink, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<UserDefinedFunction>> ReadUserDefinedFunctionPrivateAsync(string functionLink, Documents.Client.RequestOptions options, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(functionLink))
            {
                throw new ArgumentNullException("functionLink");
            }

            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Read, ResourceType.UserDefinedFunction);
            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Read,
                ResourceType.UserDefinedFunction,
                functionLink,
                AuthorizationTokenType.PrimaryMasterKey,
                headers))
            {
                return new ResourceResponse<UserDefinedFunction>(await this.ReadAsync(request, retryPolicyInstance));
            }
        }

        /// <summary>
        /// Reads a <see cref="Microsoft.Azure.Documents.Conflict"/> from the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="conflictLink">The link to the Conflict to be read.</param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <returns>
        /// A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which wraps a <see cref="Microsoft.Azure.Documents.Conflict"/> containing the read resource record.
        /// </returns>
        /// <exception cref="ArgumentNullException">If <paramref name="conflictLink"/> is not set.</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>404</term><description>NotFound - This means the resource you tried to read did not exist.</description>
        ///     </item>
        ///     <item>
        ///         <term>429</term><description>TooManyRequests - This means you have exceeded the number of request units per second. Consult the DocumentClientException.RetryAfter value to see how long you should wait before retrying this operation.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// //Reads a Conflict resource from a Database
        /// // - sample_database is the ID of the database
        /// // - sample_collection is the ID of the collection
        /// // - conflict_id is the ID of the conflict to be read
        /// var conflictLink = "/dbs/sample_database/colls/sample_collection/conflicts/conflict_id";
        /// Conflict conflict = await client.ReadConflictAsync(conflictLink);
        /// ]]>
        /// </code>
        /// </example>
        /// <remarks>
        /// <para>
        /// Doing a read of a resource is the most efficient way to get a resource from the Database. If you know the resource's ID, do a read instead of a query by ID.
        /// </para>
        /// <para>
        /// The example shown uses ID-based links, where the link is composed of the ID properties used when the resources were created.
        /// You can still use the <see cref="Microsoft.Azure.Documents.Resource.SelfLink"/> property of the Conflict if you prefer. A self-link is a URI for a resource that is made up of Resource Identifiers  (or the _rid properties).
        /// ID-based links and SelfLink will both work.
        /// The format for <paramref name="conflictLink"/> is always "/dbs/{db identifier}/colls/{collectioon identifier}/conflicts/{conflict identifier}"
        /// only the values within the {...} change depending on which method you wish to use to address the resource.
        /// </para>
        /// </remarks>
        /// <seealso cref="Microsoft.Azure.Documents.Conflict"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        /// <seealso cref="System.Uri"/>
        public Task<ResourceResponse<Conflict>> ReadConflictAsync(string conflictLink, Documents.Client.RequestOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(
                () => this.ReadConflictPrivateAsync(conflictLink, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<Conflict>> ReadConflictPrivateAsync(string conflictLink, Documents.Client.RequestOptions options, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(conflictLink))
            {
                throw new ArgumentNullException("conflictLink");
            }

            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Read, ResourceType.Conflict);
            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Read,
                ResourceType.Conflict,
                conflictLink,
                AuthorizationTokenType.PrimaryMasterKey,
                headers))
            {
                await this.AddPartitionKeyInformationAsync(request, options);
                return new ResourceResponse<Conflict>(await this.ReadAsync(request, retryPolicyInstance));
            }
        }

        /// <summary>
        /// Reads an <see cref="Microsoft.Azure.Documents.Offer"/> from the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="offerLink">The link to the Offer to be read.</param>
        /// <returns>
        /// A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which wraps a <see cref="Microsoft.Azure.Documents.Offer"/> containing the read resource record.
        /// </returns>
        /// <exception cref="ArgumentNullException">If <paramref name="offerLink"/> is not set.</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>404</term><description>NotFound - This means the resource you tried to read did not exist.</description>
        ///     </item>
        ///     <item>
        ///         <term>429</term><description>TooManyRequests - This means you have exceeded the number of request units per second. Consult the DocumentClientException.RetryAfter value to see how long you should wait before retrying this operation.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// //Reads an Offer resource from a Database
        /// // - offer_id is the ID of the offer to be read
        /// var offerLink = "/offers/offer_id";
        /// Offer offer = await client.ReadOfferAsync(offerLink);
        /// ]]>
        /// </code>
        /// </example>
        /// <remarks>
        /// <para>
        /// Doing a read of a resource is the most efficient way to get a resource from the Database. If you know the resource's ID, do a read instead of a query by ID.
        /// </para>
        /// <para>
        /// For an Offer, id is always generated internally by the system when the linked resource is created. id and _rid are always the same for Offer.
        /// </para>
        /// <para>
        /// Refer to https://docs.microsoft.com/en-us/azure/cosmos-db/how-to-provision-container-throughput to learn more about 
        /// minimum throughput of a Cosmos container (or a database)
        /// To retrieve the minimum throughput for a collection/database, use the following sample 
        /// <code language="c#">
        /// <![CDATA[
        /// // Find the offer for the collection by SelfLink
        /// Offer offer = client.CreateOfferQuery(
        ///     string.Format("SELECT * FROM offers o WHERE o.resource = '{0}'", collectionSelfLink)).AsEnumerable().FirstOrDefault();
        /// ResourceResponse<Offer> response = await client.ReadOfferAsync(offer.SelfLink);
        /// string minimumRUsForCollection = readResponse.Headers["x-ms-cosmos-min-throughput"];
        /// ]]>
        /// </code>
        /// </para>
        /// </remarks>
        /// <seealso cref="Microsoft.Azure.Documents.Conflict"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        /// <seealso cref="System.Uri"/>
        public Task<ResourceResponse<Offer>> ReadOfferAsync(string offerLink)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(
                () => this.ReadOfferPrivateAsync(offerLink, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<Offer>> ReadOfferPrivateAsync(string offerLink, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(offerLink))
            {
                throw new ArgumentNullException("offerLink");
            }

            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Read,
                ResourceType.Offer,
                offerLink,
                null,
                AuthorizationTokenType.PrimaryMasterKey))
            {
                return new ResourceResponse<Offer>(await this.ReadAsync(request, retryPolicyInstance), OfferTypeResolver.ResponseOfferTypeResolver);
            }
        }

        /// <summary>
        /// Reads a <see cref="Microsoft.Azure.Documents.Schema"/> as an asynchronous operation.
        /// </summary>
        /// <param name="documentSchemaLink">The link for the schema to be read.</param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <returns>
        /// A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which wraps a <see cref="Microsoft.Azure.Documents.Document"/> containing the read resource record.
        /// </returns>
        /// <exception cref="ArgumentNullException">If <paramref name="documentSchemaLink"/> is not set.</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when reading a Schema are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>404</term><description>NotFound - This means the resource you tried to read did not exist.</description>
        ///     </item>
        ///     <item>
        ///         <term>429</term><description>TooManyRequests - This means you have exceeded the number of request units per second. Consult the DocumentClientException.RetryAfter value to see how long you should wait before retrying this operation.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// //This reads a schema record from a database & collection where
        /// // - sample_database is the ID of the database
        /// // - sample_collection is the ID of the collection
        /// // - schema_id is the ID of the document resource
        /// var docLink = "/dbs/sample_database/colls/sample_collection/schemas/schemas_id";
        /// Schema schema = await client.ReadSchemaAsync(docLink);
        /// ]]>
        /// </code>
        /// </example>
        /// <remarks>
        /// <para>
        /// Doing a read of a resource is the most efficient way to get a resource from the Database. If you know the resource's ID, do a read instead of a query by ID.
        /// </para>
        /// <para>
        /// The example shown uses ID-based links, where the link is composed of the ID properties used when the resources were created.
        /// You can still use the <see cref="Microsoft.Azure.Documents.Resource.SelfLink"/> property of the Document if you prefer. A self-link is a URI for a resource that is made up of Resource Identifiers  (or the _rid properties).
        /// ID-based links and SelfLink will both work.
        /// The format for <paramref name="documentSchemaLink"/> is always "/dbs/{db identifier}/colls/{coll identifier}/schema/{schema identifier}" only
        /// the values within the {} change depending on which method you wish to use to address the resource.
        /// </para>
        /// </remarks>
        /// <seealso cref="Microsoft.Azure.Documents.Schema"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        /// <seealso cref="System.Uri"/>
        internal Task<ResourceResponse<Schema>> ReadSchemaAsync(string documentSchemaLink, Documents.Client.RequestOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(
                () => this.ReadSchemaPrivateAsync(documentSchemaLink, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<Schema>> ReadSchemaPrivateAsync(string documentSchemaLink, Documents.Client.RequestOptions options, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(documentSchemaLink))
            {
                throw new ArgumentNullException("documentSchemaLink");
            }

            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Read, ResourceType.Schema);
            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Read,
                ResourceType.Schema,
                documentSchemaLink,
                AuthorizationTokenType.PrimaryMasterKey,
                headers))
            {
                await this.AddPartitionKeyInformationAsync(request, options);
                request.SerializerSettings = this.GetSerializerSettingsForRequest(options);
                return new ResourceResponse<Schema>(await this.ReadAsync(request, retryPolicyInstance));
            }
        }

        /// <summary>
        /// Reads a <see cref="Microsoft.Azure.Documents.UserDefinedType"/> from the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="userDefinedTypeLink">The link to the UserDefinedType resource to be read.</param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <returns>
        /// A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which wraps a <see cref="Microsoft.Azure.Documents.UserDefinedType"/> containing the read resource record.
        /// </returns>
        /// <exception cref="ArgumentNullException">If <paramref name="userDefinedTypeLink"/> is not set.</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a UserDefinedType are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>404</term><description>NotFound - This means the resource you tried to read did not exist.</description>
        ///     </item>
        ///     <item>
        ///         <term>429</term><description>TooManyRequests - This means you have exceeded the number of request units per second. Consult the DocumentClientException.RetryAfter value to see how long you should wait before retrying this operation.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// //Reads a User resource from a Database
        /// // - sample_database is the ID of the database
        /// // - userDefinedType_id is the ID of the user defined type to be read
        /// var userDefinedTypeLink = "/dbs/sample_database/udts/userDefinedType_id";
        /// UserDefinedType userDefinedType = await client.ReadUserDefinedTypeAsync(userDefinedTypeLink);
        /// ]]>
        /// </code>
        /// </example>
        /// <remarks>
        /// <para>
        /// Doing a read of a resource is the most efficient way to get a resource from the Database. If you know the resource's ID, do a read instead of a query by ID.
        /// </para>
        /// <para>
        /// The example shown user defined type ID-based links, where the link is composed of the ID properties used when the resources were created.
        /// You can still use the <see cref="Microsoft.Azure.Documents.Resource.SelfLink"/> property of the UserDefinedType if you prefer. A self-link is a URI for a resource that is made up of Resource Identifiers  (or the _rid properties).
        /// ID-based links and SelfLink will both work.
        /// The format for <paramref name="userDefinedTypeLink"/> is always "/dbs/{db identifier}/udts/{user defined type identifier}"
        /// only the values within the {...} change depending on which method you wish to use to address the resource.
        /// </para>
        /// </remarks>
        /// <seealso cref="Microsoft.Azure.Documents.UserDefinedType"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        /// <seealso cref="System.Uri"/>
        internal Task<ResourceResponse<UserDefinedType>> ReadUserDefinedTypeAsync(string userDefinedTypeLink, Documents.Client.RequestOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(
                () => this.ReadUserDefinedTypePrivateAsync(userDefinedTypeLink, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<UserDefinedType>> ReadUserDefinedTypePrivateAsync(string userDefinedTypeLink, Documents.Client.RequestOptions options, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(userDefinedTypeLink))
            {
                throw new ArgumentNullException("userDefinedTypeLink");
            }

            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Read, ResourceType.UserDefinedType);
            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Read,
                ResourceType.UserDefinedType,
                userDefinedTypeLink,
                AuthorizationTokenType.PrimaryMasterKey,
                headers))
            {
                return new ResourceResponse<UserDefinedType>(await this.ReadAsync(request, retryPolicyInstance));
            }
        }

        /// <summary>
        /// Reads a <see cref="Microsoft.Azure.Documents.Snapshot"/> from the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="snapshotLink">The link of the Snapshot resource to be read.</param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <returns>
        /// A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which wraps a <see cref="Microsoft.Azure.Documents.Snapshot"/> containing the read resource record.
        /// </returns>
        /// <exception cref="ArgumentNullException">If <paramref name="snapshotLink"/> is not set.</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when reading a Snapshot are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>404</term><description>NotFound - This means the resource you tried to read did not exist.</description>
        ///     </item>
        ///     <item>
        ///         <term>429</term><description>TooManyRequests - This means you have exceeded the number of request units per second. Consult the DocumentClientException.RetryAfter value to see how long you should wait before retrying this operation.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// //Reads a Snapshot resource where
        /// // - snapshot_id is the ID property of the Snapshot resource you wish to read.
        /// var snapshotLink = "/snapshots/snapshot_id";
        /// Snapshot snapshot= await client.ReadSnapshotAsync(snapshotLink);
        /// ]]>
        /// </code>
        /// </example>
        /// <remarks>
        /// <para>
        /// Doing a read of a resource is the most efficient way to get a resource from the Azure Cosmos DB service. If you know the resource's ID, do a read instead of a query by ID.
        /// </para>
        /// <para>
        /// The example shown uses ID-based links, where the link is composed of the ID properties used when the resources were created.
        /// You can still use the <see cref="Microsoft.Azure.Documents.Resource.SelfLink"/> property of the Snapshot if you prefer. A self-link is a URI for a resource that is made up of Resource Identifiers  (or the _rid properties).
        /// ID-based links and SelfLink will both work.
        /// The format for <paramref name="snapshotLink"/> is always "/snapshots/{snapshot identifier}" only
        /// the values within the {} change depending on which method you wish to use to address the resource.
        /// </para>
        /// </remarks>
        /// <seealso cref="Microsoft.Azure.Documents.Snapshot"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        /// <seealso cref="System.Uri"/>
        internal Task<ResourceResponse<Snapshot>> ReadSnapshotAsync(string snapshotLink, Documents.Client.RequestOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(() => this.ReadSnapshotPrivateAsync(snapshotLink, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<Snapshot>> ReadSnapshotPrivateAsync(string snapshotLink, Documents.Client.RequestOptions options, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(snapshotLink))
            {
                throw new ArgumentNullException("snapshotLink");
            }

            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Read, ResourceType.Snapshot);
            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Read,
                ResourceType.Snapshot,
                snapshotLink,
                AuthorizationTokenType.PrimaryMasterKey,
                headers))
            {
                return new ResourceResponse<Snapshot>(await this.ReadAsync(request, retryPolicyInstance));
            }
        }

        #endregion

        #region ReadFeed Impl
        /// <summary>
        /// Reads the feed (sequence) of <see cref="Microsoft.Azure.Documents.Database"/> for a database account from the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <returns>
        /// A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which wraps a <see cref="Microsoft.Azure.Documents.Database"/> containing the read resource record.
        /// </returns>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>429</term><description>TooManyRequests - This means you have exceeded the number of request units per second. Consult the DocumentClientException.RetryAfter value to see how long you should wait before retrying this operation.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// int count = 0;
        /// string continuation = string.Empty;
        /// do
        /// {
        ///     // Read the feed 10 items at a time until there are no more items to read
        ///     DoucmentFeedResponse<Database> response = await client.ReadDatabaseFeedAsync(new FeedOptions
        ///                                                                 {
        ///                                                                     MaxItemCount = 10,
        ///                                                                     RequestContinuation = continuation
        ///                                                                 });
        ///
        ///     // Append the item count
        ///     count += response.Count;
        ///
        ///     // Get the continuation so that we know when to stop.
        ///      continuation = response.ResponseContinuation;
        /// } while (!string.IsNullOrEmpty(continuation));
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.Database"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<DocumentFeedResponse<Documents.Database>> ReadDatabaseFeedAsync(FeedOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(
                () => this.ReadDatabaseFeedPrivateAsync(options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<DocumentFeedResponse<Documents.Database>> ReadDatabaseFeedPrivateAsync(FeedOptions options, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            return await this.CreateDatabaseFeedReader(options).ExecuteNextAsync();
        }

        /// <summary>
        /// Reads the feed (sequence) of <see cref="Microsoft.Azure.Documents.PartitionKeyRange"/> for a database account from the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="partitionKeyRangesOrCollectionLink">The link of the resources to be read, or owner collection link, SelfLink or AltLink. E.g. /dbs/db_rid/colls/coll_rid/pkranges</param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <returns>
        /// A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which wraps a <see cref="Microsoft.Azure.Documents.Database"/> containing the read resource record.
        /// </returns>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>429</term><description>TooManyRequests - This means you have exceeded the number of request units per second. Consult the DocumentClientException.RetryAfter value to see how long you should wait before retrying this operation.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// DoucmentFeedResponse<PartitionKeyRange> response = null;
        /// List<string> ids = new List<string>();
        /// do
        /// {
        ///     response = await client.ReadPartitionKeyRangeFeedAsync(collection.SelfLink, new FeedOptions { MaxItemCount = 1000 });
        ///     foreach (var item in response)
        ///     {
        ///         ids.Add(item.Id);
        ///     }
        /// }
        /// while (!string.IsNullOrEmpty(response.ResponseContinuation));
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.PartitionKeyRange"/>
        /// <seealso cref="Microsoft.Azure.Cosmos.FeedOptions"/>
        /// <seealso cref="Microsoft.Azure.Cosmos.DocumentFeedResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<DocumentFeedResponse<PartitionKeyRange>> ReadPartitionKeyRangeFeedAsync(string partitionKeyRangesOrCollectionLink, FeedOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(
                () => this.ReadPartitionKeyRangeFeedPrivateAsync(partitionKeyRangesOrCollectionLink, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<DocumentFeedResponse<PartitionKeyRange>> ReadPartitionKeyRangeFeedPrivateAsync(string partitionKeyRangesLink, FeedOptions options, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(partitionKeyRangesLink))
            {
                throw new ArgumentNullException("partitionKeyRangesLink");
            }

            return await this.CreatePartitionKeyRangeFeedReader(partitionKeyRangesLink, options).ExecuteNextAsync();
        }

        /// <summary>
        /// Reads the feed (sequence) of <see cref="Microsoft.Azure.Documents.DocumentCollection"/> for a database from the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="collectionsLink">The SelfLink of the resources to be read. E.g. /dbs/db_rid/colls/ </param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <returns>
        /// A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which wraps a <see cref="Microsoft.Azure.Documents.DocumentCollection"/> containing the read resource record.
        /// </returns>
        /// <exception cref="ArgumentNullException">If <paramref name="collectionsLink"/> is not set.</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>404</term><description>NotFound - This means the resource feed you tried to read did not exist. Check the parent rids are correct.</description>
        ///     </item>
        ///     <item>
        ///         <term>429</term><description>TooManyRequests - This means you have exceeded the number of request units per second. Consult the DocumentClientException.RetryAfter value to see how long you should wait before retrying this operation.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// int count = 0;
        /// string continuation = string.Empty;
        /// do
        /// {
        ///     // Read the feed 10 items at a time until there are no more items to read
        ///     DoucmentFeedResponse<DocumentCollection> response = await client.ReadDocumentCollectionFeedAsync("/dbs/db_rid/colls/",
        ///                                                     new FeedOptions
        ///                                                     {
        ///                                                         MaxItemCount = 10,
        ///                                                         RequestContinuation = continuation
        ///                                                     });
        ///
        ///     // Append the item count
        ///     count += response.Count;
        ///
        ///     // Get the continuation so that we know when to stop.
        ///      continuation = response.ResponseContinuation;
        /// } while (!string.IsNullOrEmpty(continuation));
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.DocumentCollection"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<DocumentFeedResponse<DocumentCollection>> ReadDocumentCollectionFeedAsync(string collectionsLink, FeedOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(
                () => this.ReadDocumentCollectionFeedPrivateAsync(collectionsLink, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<DocumentFeedResponse<DocumentCollection>> ReadDocumentCollectionFeedPrivateAsync(string collectionsLink, FeedOptions options, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(collectionsLink))
            {
                throw new ArgumentNullException("collectionsLink");
            }

            return await this.CreateDocumentCollectionFeedReader(collectionsLink, options).ExecuteNextAsync();
        }

        /// <summary>
        /// Reads the feed (sequence) of <see cref="Microsoft.Azure.Documents.StoredProcedure"/> for a collection from the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="storedProceduresLink">The SelfLink of the resources to be read. E.g. /dbs/db_rid/colls/col_rid/sprocs/ </param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <returns>
        /// A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which wraps a <see cref="Microsoft.Azure.Documents.StoredProcedure"/> containing the read resource record.
        /// </returns>
        /// <exception cref="ArgumentNullException">If <paramref name="storedProceduresLink"/> is not set.</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>404</term><description>NotFound - This means the resource feed you tried to read did not exist. Check the parent rids are correct.</description>
        ///     </item>
        ///     <item>
        ///         <term>429</term><description>TooManyRequests - This means you have exceeded the number of request units per second. Consult the DocumentClientException.RetryAfter value to see how long you should wait before retrying this operation.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// int count = 0;
        /// string continuation = string.Empty;
        /// do
        /// {
        ///     // Read the feed 10 items at a time until there are no more items to read
        ///     DoucmentFeedResponse<StoredProcedure> response = await client.ReadStoredProcedureFeedAsync("/dbs/db_rid/colls/col_rid/sprocs/",
        ///                                                     new FeedOptions
        ///                                                     {
        ///                                                         MaxItemCount = 10,
        ///                                                         RequestContinuation = continuation
        ///                                                     });
        ///
        ///     // Append the item count
        ///     count += response.Count;
        ///
        ///     // Get the continuation so that we know when to stop.
        ///      continuation = response.ResponseContinuation;
        /// } while (!string.IsNullOrEmpty(continuation));
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.StoredProcedure"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<DocumentFeedResponse<StoredProcedure>> ReadStoredProcedureFeedAsync(string storedProceduresLink, FeedOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(
                () => this.ReadStoredProcedureFeedPrivateAsync(storedProceduresLink, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<DocumentFeedResponse<StoredProcedure>> ReadStoredProcedureFeedPrivateAsync(string storedProceduresLink, FeedOptions options, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(storedProceduresLink))
            {
                throw new ArgumentNullException("storedProceduresLink");
            }

            return await this.CreateStoredProcedureFeedReader(storedProceduresLink, options).ExecuteNextAsync();
        }

        /// <summary>
        /// Reads the feed (sequence) of <see cref="Microsoft.Azure.Documents.Trigger"/> for a collection from the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="triggersLink">The SelfLink of the resources to be read. E.g. /dbs/db_rid/colls/col_rid/triggers/ </param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <returns>
        /// A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which wraps a <see cref="Microsoft.Azure.Documents.Trigger"/> containing the read resource record.
        /// </returns>
        /// <exception cref="ArgumentNullException">If <paramref name="triggersLink"/> is not set.</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>404</term><description>NotFound - This means the resource feed you tried to read did not exist. Check the parent rids are correct.</description>
        ///     </item>
        ///     <item>
        ///         <term>429</term><description>TooManyRequests - This means you have exceeded the number of request units per second. Consult the DocumentClientException.RetryAfter value to see how long you should wait before retrying this operation.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// int count = 0;
        /// string continuation = string.Empty;
        /// do
        /// {
        ///     // Read the feed 10 items at a time until there are no more items to read
        ///     DoucmentFeedResponse<Trigger> response = await client.ReadTriggerFeedAsync("/dbs/db_rid/colls/col_rid/triggers/",
        ///                                                     new FeedOptions
        ///                                                     {
        ///                                                         MaxItemCount = 10,
        ///                                                         RequestContinuation = continuation
        ///                                                     });
        ///
        ///     // Append the item count
        ///     count += response.Count;
        ///
        ///     // Get the continuation so that we know when to stop.
        ///      continuation = response.ResponseContinuation;
        /// } while (!string.IsNullOrEmpty(continuation));
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.Trigger"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<DocumentFeedResponse<Trigger>> ReadTriggerFeedAsync(string triggersLink, FeedOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(
                () => this.ReadTriggerFeedPrivateAsync(triggersLink, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<DocumentFeedResponse<Trigger>> ReadTriggerFeedPrivateAsync(string triggersLink, FeedOptions options, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(triggersLink))
            {
                throw new ArgumentNullException("triggersLink");
            }

            return await this.CreateTriggerFeedReader(triggersLink, options).ExecuteNextAsync();
        }

        /// <summary>
        /// Reads the feed (sequence) of <see cref="Microsoft.Azure.Documents.UserDefinedFunction"/> for a collection from the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="userDefinedFunctionsLink">The SelfLink of the resources to be read. E.g. /dbs/db_rid/colls/col_rid/udfs/ </param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <returns>
        /// A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which wraps a <see cref="Microsoft.Azure.Documents.UserDefinedFunction"/> containing the read resource record.
        /// </returns>
        /// <exception cref="ArgumentNullException">If <paramref name="userDefinedFunctionsLink"/> is not set.</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>404</term><description>NotFound - This means the resource feed you tried to read did not exist. Check the parent rids are correct.</description>
        ///     </item>
        ///     <item>
        ///         <term>429</term><description>TooManyRequests - This means you have exceeded the number of request units per second. Consult the DocumentClientException.RetryAfter value to see how long you should wait before retrying this operation.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// int count = 0;
        /// string continuation = string.Empty;
        /// do
        /// {
        ///     // Read the feed 10 items at a time until there are no more items to read
        ///     DoucmentFeedResponse<UserDefinedFunction> response = await client.ReadUserDefinedFunctionFeedAsync("/dbs/db_rid/colls/col_rid/udfs/",
        ///                                                     new FeedOptions
        ///                                                     {
        ///                                                         MaxItemCount = 10,
        ///                                                         RequestContinuation = continuation
        ///                                                     });
        ///
        ///     // Append the item count
        ///     count += response.Count;
        ///
        ///     // Get the continuation so that we know when to stop.
        ///      continuation = response.ResponseContinuation;
        /// } while (!string.IsNullOrEmpty(continuation));
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.UserDefinedFunction"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<DocumentFeedResponse<UserDefinedFunction>> ReadUserDefinedFunctionFeedAsync(string userDefinedFunctionsLink, FeedOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(
                () => this.ReadUserDefinedFunctionFeedPrivateAsync(userDefinedFunctionsLink, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<DocumentFeedResponse<UserDefinedFunction>> ReadUserDefinedFunctionFeedPrivateAsync(string userDefinedFunctionsLink, FeedOptions options, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(userDefinedFunctionsLink))
            {
                throw new ArgumentNullException("userDefinedFunctionsLink");
            }

            return await this.CreateUserDefinedFunctionFeedReader(userDefinedFunctionsLink, options).ExecuteNextAsync();
        }

        /// <summary>
        /// Reads the feed (sequence) of documents for a specified collection from the Azure Cosmos DB service.
        /// This takes returns a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which will contain an enumerable list of dynamic objects.
        /// </summary>
        /// <param name="documentsLink">The SelfLink of the resources to be read. E.g. /dbs/db_rid/colls/coll_rid/docs/ </param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <param name="cancellationToken">(Optional) A <see cref="CancellationToken"/> that can be used by other objects or threads to receive notice of cancellation.</param>
        /// <returns>
        /// A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> containing dynamic objects representing the items in the feed.
        /// </returns>
        /// <exception cref="ArgumentNullException">If <paramref name="documentsLink"/> is not set.</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>404</term><description>NotFound - This means the resource feed you tried to read did not exist. Check the parent rids are correct.</description>
        ///     </item>
        ///     <item>
        ///         <term>429</term><description>TooManyRequests - This means you have exceeded the number of request units per second. Consult the DocumentClientException.RetryAfter value to see how long you should wait before retrying this operation.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// int count = 0;
        /// string continuation = string.Empty;
        /// do
        /// {
        ///     // Read the feed 10 items at a time until there are no more items to read
        ///     DoucmentFeedResponse<dynamic> response = await client.ReadDocumentFeedAsync("/dbs/db_rid/colls/coll_rid/docs/",
        ///                                                     new FeedOptions
        ///                                                     {
        ///                                                         MaxItemCount = 10,
        ///                                                         RequestContinuation = continuation
        ///                                                     });
        ///
        ///     // Append the item count
        ///     count += response.Count;
        ///
        ///     // Get the continuation so that we know when to stop.
        ///      continuation = response.ResponseContinuation;
        /// } while (!string.IsNullOrEmpty(continuation));
        /// ]]>
        /// </code>
        /// </example>
        /// <remarks>
        /// Instead of DoucmentFeedResponse{Document} this method takes advantage of dynamic objects in .NET. This way a single feed result can contain any kind of Document, or POCO object.
        /// This is important becuse a DocumentCollection can contain different kinds of documents.
        /// </remarks>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<DocumentFeedResponse<dynamic>> ReadDocumentFeedAsync(string documentsLink, FeedOptions options = null, CancellationToken cancellationToken = default)
        {
            return TaskHelper.InlineIfPossible(() => this.ReadDocumentFeedInlineAsync(documentsLink, options, cancellationToken), null, cancellationToken);
        }

        private async Task<DocumentFeedResponse<dynamic>> ReadDocumentFeedInlineAsync(string documentsLink, FeedOptions options, CancellationToken cancellationToken)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(documentsLink))
            {
                throw new ArgumentNullException("documentsLink");
            }

            DocumentFeedResponse<Document> response = await this.CreateDocumentFeedReader(documentsLink, options).ExecuteNextAsync(cancellationToken);
            return new DocumentFeedResponse<dynamic>(
                response.Cast<dynamic>(),
                response.Count,
                response.Headers,
                response.UseETagAsContinuation,
                response.QueryMetrics,
                response.RequestStatistics,
                responseLengthBytes: response.ResponseLengthBytes);
        }

        /// <summary>
        /// Reads the feed (sequence) of <see cref="Microsoft.Azure.Documents.Conflict"/> for a collection from the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="conflictsLink">The SelfLink of the resources to be read. E.g. /dbs/db_rid/colls/coll_rid/conflicts/ </param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <returns>
        /// A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which wraps a <see cref="Microsoft.Azure.Documents.Conflict"/> containing the read resource record.
        /// </returns>
        /// <exception cref="ArgumentNullException">If <paramref name="conflictsLink"/> is not set.</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>404</term><description>NotFound - This means the resource feed you tried to read did not exist. Check the parent rids are correct.</description>
        ///     </item>
        ///     <item>
        ///         <term>429</term><description>TooManyRequests - This means you have exceeded the number of request units per second. Consult the DocumentClientException.RetryAfter value to see how long you should wait before retrying this operation.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// int count = 0;
        /// string continuation = string.Empty;
        /// do
        /// {
        ///     // Read the feed 10 items at a time until there are no more items to read
        ///     DoucmentFeedResponse<Conflict> response = await client.ReadConflictAsync("/dbs/db_rid/colls/coll_rid/conflicts/",
        ///                                                     new FeedOptions
        ///                                                     {
        ///                                                         MaxItemCount = 10,
        ///                                                         RequestContinuation = continuation
        ///                                                     });
        ///
        ///     // Append the item count
        ///     count += response.Count;
        ///
        ///     // Get the continuation so that we know when to stop.
        ///      continuation = response.ResponseContinuation;
        /// } while (!string.IsNullOrEmpty(continuation));
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.Conflict"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<DocumentFeedResponse<Conflict>> ReadConflictFeedAsync(string conflictsLink, FeedOptions options = null)
        {
            return TaskHelper.InlineIfPossible(() => this.ReadConflictFeedInlineAsync(conflictsLink, options), null);
        }

        private async Task<DocumentFeedResponse<Conflict>> ReadConflictFeedInlineAsync(string conflictsLink, FeedOptions options)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(conflictsLink))
            {
                throw new ArgumentNullException("conflictsLink");
            }

            return await this.CreateConflictFeedReader(conflictsLink, options).ExecuteNextAsync();
        }

        /// <summary>
        /// Reads the feed (sequence) of <see cref="Microsoft.Azure.Documents.Offer"/> for a database account from the Azure Cosmos DB service
        /// as an asynchronous operation.
        /// </summary>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <returns>
        /// A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which wraps a <see cref="Microsoft.Azure.Documents.Offer"/> containing the read resource record.
        /// </returns>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>429</term><description>TooManyRequests - This means you have exceeded the number of request units per second. Consult the DocumentClientException.RetryAfter value to see how long you should wait before retrying this operation.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// int count = 0;
        /// string continuation = string.Empty;
        /// do
        /// {
        ///     // Read the feed 10 items at a time until there are no more items to read
        ///     DoucmentFeedResponse<Offer> response = await client.ReadOfferAsync(new FeedOptions
        ///                                                                 {
        ///                                                                     MaxItemCount = 10,
        ///                                                                     RequestContinuation = continuation
        ///                                                                 });
        ///
        ///     // Append the item count
        ///     count += response.Count;
        ///
        ///     // Get the continuation so that we know when to stop.
        ///      continuation = response.ResponseContinuation;
        /// } while (!string.IsNullOrEmpty(continuation));
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.Offer"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<DocumentFeedResponse<Offer>> ReadOffersFeedAsync(FeedOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(
                () => this.ReadOfferFeedPrivateAsync(options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<DocumentFeedResponse<Offer>> ReadOfferFeedPrivateAsync(FeedOptions options, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            return await this.CreateOfferFeedReader(options).ExecuteNextAsync();
        }

        /// <summary>
        /// Reads the feed (sequence) of <see cref="Microsoft.Azure.Documents.Schema"/> for a collection as an asynchronous operation.
        /// </summary>
        /// <param name="documentCollectionSchemaLink">The SelfLink of the resources to be read. E.g. /dbs/db_rid/colls/coll_rid/schemas </param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <returns>
        /// A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which wraps a <see cref="Microsoft.Azure.Documents.Schema"/> containing the read resource record.
        /// </returns>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>404</term><description>NotFound - This means the resource feed you tried to read did not exist. Check the parent rids are correct.</description>
        ///     </item>
        ///     <item>
        ///         <term>429</term><description>TooManyRequests - This means you have exceeded the number of request units per second. Consult the DocumentClientException.RetryAfter value to see how long you should wait before retrying this operation.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// int count = 0;
        /// string continuation = string.Empty;
        /// do
        /// {
        ///     // Read the feed 10 items at a time until there are no more items to read
        ///     DoucmentFeedResponse<User> response = await client.ReadUserFeedAsync("/dbs/db_rid/colls/coll_rid/schemas",
        ///                                                     new FeedOptions
        ///                                                     {
        ///                                                         MaxItemCount = 10,
        ///                                                         RequestContinuation = continuation
        ///                                                     });
        ///
        ///     // Append the item count
        ///     count += response.Count;
        ///
        ///     // Get the continuation so that we know when to stop.
        ///      continuation = response.ResponseContinuation;
        /// } while (!string.IsNullOrEmpty(continuation));
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.Schema"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        internal Task<DocumentFeedResponse<Schema>> ReadSchemaFeedAsync(string documentCollectionSchemaLink, FeedOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(() => this.ReadSchemaFeedPrivateAsync(documentCollectionSchemaLink, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<DocumentFeedResponse<Schema>> ReadSchemaFeedPrivateAsync(string documentCollectionSchemaLink, FeedOptions options, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(documentCollectionSchemaLink))
            {
                throw new ArgumentNullException("documentCollectionSchemaLink");
            }

            return await this.CreateSchemaFeedReader(documentCollectionSchemaLink, options).ExecuteNextAsync();
        }

        /// <summary>
        /// Reads the feed (sequence) of <see cref="Microsoft.Azure.Documents.UserDefinedType"/> for a database from the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="userDefinedTypesLink">The SelfLink of the resources to be read. E.g. /dbs/db_rid/udts/ </param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <returns>
        /// A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/> which wraps a <see cref="Microsoft.Azure.Documents.UserDefinedType"/> containing the read resource record.
        /// </returns>
        /// <exception cref="ArgumentNullException">If <paramref name="userDefinedTypesLink"/> is not set.</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a UserDefinedType are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>404</term><description>NotFound - This means the resource feed you tried to read did not exist. Check the parent rids are correct.</description>
        ///     </item>
        ///     <item>
        ///         <term>429</term><description>TooManyRequests - This means you have exceeded the number of request units per second. Consult the DocumentClientException.RetryAfter value to see how long you should wait before retrying this operation.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// int count = 0;
        /// string continuation = string.Empty;
        /// do
        /// {
        ///     // Read the feed 10 items at a time until there are no more items to read
        ///     DoucmentFeedResponse<UserDefinedType> response = await client.ReadUserDefinedTypeFeedAsync("/dbs/db_rid/udts/",
        ///                                                     new FeedOptions
        ///                                                     {
        ///                                                         MaxItemCount = 10,
        ///                                                         RequestContinuation = continuation
        ///                                                     });
        ///
        ///     // Append the item count
        ///     count += response.Count;
        ///
        ///     // Get the continuation so that we know when to stop.
        ///      continuation = response.ResponseContinuation;
        /// } while (!string.IsNullOrEmpty(continuation));
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.UserDefinedType"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        internal Task<DocumentFeedResponse<UserDefinedType>> ReadUserDefinedTypeFeedAsync(string userDefinedTypesLink, FeedOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(
                () => this.ReadUserDefinedTypeFeedPrivateAsync(userDefinedTypesLink, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<DocumentFeedResponse<UserDefinedType>> ReadUserDefinedTypeFeedPrivateAsync(string userDefinedTypesLink, FeedOptions options, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(userDefinedTypesLink))
            {
                throw new ArgumentNullException("userDefinedTypesLink");
            }

            return await this.CreateUserDefinedTypeFeedReader(userDefinedTypesLink, options).ExecuteNextAsync();
        }

        /// <summary>
        /// Reads the feed (sequence) of <see cref="Microsoft.Azure.Documents.Snapshot"/> for a database account from the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <returns>
        /// A <see cref="System.Threading.Tasks"/> containing a <see cref="Microsoft.Azure.Cosmos.DocumentFeedResponse{T}"/> which wraps a set of <see cref="Microsoft.Azure.Documents.Snapshot"/> containing the read resource record.
        /// </returns>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>429</term><description>TooManyRequests - This means you have exceeded the number of request units per second. Consult the DocumentClientException.RetryAfter value to see how long you should wait before retrying this operation.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// int count = 0;
        /// string continuation = string.Empty;
        /// do
        /// {
        ///     // Read the feed 10 items at a time until there are no more items to read
        ///     DocumentFeedResponse<Snapshot> response = await client.ReadSnapshotFeedAsync(new FeedOptions
        ///                                                                 {
        ///                                                                     MaxItemCount = 10,
        ///                                                                     RequestContinuation = continuation
        ///                                                                 });
        ///
        ///     // Append the item count
        ///     count += response.Count;
        ///
        ///     // Get the continuation so that we know when to stop.
        ///      continuation = response.ResponseContinuation;
        /// } while (!string.IsNullOrEmpty(continuation));
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.Snapshot"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        internal Task<DocumentFeedResponse<Snapshot>> ReadSnapshotFeedAsync(FeedOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(
                () => this.ReadSnapshotFeedPrivateAsync(options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<DocumentFeedResponse<Snapshot>> ReadSnapshotFeedPrivateAsync(FeedOptions options, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            return await this.CreateSnapshotFeedReader(options).ExecuteNextAsync();
        }

        #endregion

        #region Stored procs
        /// <summary>
        /// Executes a stored procedure against a collection as an asynchronous operation in the Azure Cosmos DB service.
        /// </summary>
        /// <typeparam name="TValue">The type of the stored procedure's return value.</typeparam>
        /// <param name="storedProcedureLink">The link to the stored procedure to execute.</param>
        /// <param name="procedureParams">(Optional) An array of dynamic objects representing the parameters for the stored procedure.</param>
        /// <exception cref="ArgumentNullException">If <paramref name="storedProcedureLink"/> is not set.</exception>
        /// <returns>The task object representing the service response for the asynchronous operation which would contain any response set in the stored procedure.</returns>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// //Execute a StoredProcedure with ResourceId of "sproc_rid" that takes two "Player" documents, does some stuff, and returns a bool
        /// StoredProcedureResponse<bool> sprocResponse = await client.ExecuteStoredProcedureAsync<bool>(
        ///                                                         "/dbs/db_rid/colls/col_rid/sprocs/sproc_rid/",
        ///                                                         new Player { id="1", name="joe" } ,
        ///                                                         new Player { id="2", name="john" }
        ///                                                     );
        ///
        /// if (sprocResponse.Response) Console.WriteLine("Congrats, the stored procedure did some stuff");
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.StoredProcedure"/>
        /// <seealso cref="Microsoft.Azure.Cosmos.StoredProcedureResponse{TValue}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<StoredProcedureResponse<TValue>> ExecuteStoredProcedureAsync<TValue>(string storedProcedureLink, params dynamic[] procedureParams)
        {
            return this.ExecuteStoredProcedureAsync<TValue>(storedProcedureLink, null, default, procedureParams);
        }

        /// <summary>
        /// Executes a stored procedure against a partitioned collection in the Azure Cosmos DB service as an asynchronous operation, specifiying a target partition.
        /// </summary>
        /// <typeparam name="TValue">The type of the stored procedure's return value.</typeparam>
        /// <param name="storedProcedureLink">The link to the stored procedure to execute.</param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <param name="procedureParams">(Optional) An array of dynamic objects representing the parameters for the stored procedure.</param>
        /// <exception cref="ArgumentNullException">If <paramref name="storedProcedureLink"/> is not set.</exception>
        /// <returns>The task object representing the service response for the asynchronous operation which would contain any response set in the stored procedure.</returns>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// //Execute a StoredProcedure with ResourceId of "sproc_rid" that takes two "Player" documents, does some stuff, and returns a bool
        /// StoredProcedureResponse<bool> sprocResponse = await client.ExecuteStoredProcedureAsync<bool>(
        ///                                                         "/dbs/db_rid/colls/col_rid/sprocs/sproc_rid/",
        ///                                                         new RequestOptions { PartitionKey = new PartitionKey(1) },
        ///                                                         new Player { id="1", name="joe" } ,
        ///                                                         new Player { id="2", name="john" }
        ///                                                     );
        ///
        /// if (sprocResponse.Response) Console.WriteLine("Congrats, the stored procedure did some stuff");
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.StoredProcedure"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Cosmos.StoredProcedureResponse{TValue}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<StoredProcedureResponse<TValue>> ExecuteStoredProcedureAsync<TValue>(string storedProcedureLink, Documents.Client.RequestOptions options, params dynamic[] procedureParams)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(
                () => this.ExecuteStoredProcedurePrivateAsync<TValue>(
                    storedProcedureLink,
                    options,
                    retryPolicyInstance,
                    default,
                    procedureParams),
                retryPolicyInstance);
        }

        /// <summary>
        /// Executes a stored procedure against a partitioned collection in the Azure Cosmos DB service as an asynchronous operation, specifiying a target partition.
        /// </summary>
        /// <typeparam name="TValue">The type of the stored procedure's return value.</typeparam>
        /// <param name="storedProcedureLink">The link to the stored procedure to execute.</param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <param name="cancellationToken">(Optional) A <see cref="CancellationToken"/> that can be used by other objects or threads to receive notice of cancellation.</param>
        /// <param name="procedureParams">(Optional) An array of dynamic objects representing the parameters for the stored procedure.</param>
        /// <exception cref="ArgumentNullException">If <paramref name="storedProcedureLink"/> is not set.</exception>
        /// <returns>The task object representing the service response for the asynchronous operation which would contain any response set in the stored procedure.</returns>
        /// <example>
        /// <code language="c#">
        /// <![CDATA[
        /// //Execute a StoredProcedure with ResourceId of "sproc_rid" that takes two "Player" documents, does some stuff, and returns a bool
        /// StoredProcedureResponse<bool> sprocResponse = await client.ExecuteStoredProcedureAsync<bool>(
        ///                                                         "/dbs/db_rid/colls/col_rid/sprocs/sproc_rid/",
        ///                                                         new RequestOptions { PartitionKey = new PartitionKey(1) },
        ///                                                         new Player { id="1", name="joe" } ,
        ///                                                         new Player { id="2", name="john" }
        ///                                                     );
        ///
        /// if (sprocResponse.Response) Console.WriteLine("Congrats, the stored procedure did some stuff");
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.StoredProcedure"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Cosmos.StoredProcedureResponse{TValue}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<StoredProcedureResponse<TValue>> ExecuteStoredProcedureAsync<TValue>(string storedProcedureLink, Documents.Client.RequestOptions options, CancellationToken cancellationToken, params dynamic[] procedureParams)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(
                () => this.ExecuteStoredProcedurePrivateAsync<TValue>(
                    storedProcedureLink,
                    options,
                    retryPolicyInstance,
                    cancellationToken,
                    procedureParams),
                retryPolicyInstance,
                cancellationToken);
        }

        private async Task<StoredProcedureResponse<TValue>> ExecuteStoredProcedurePrivateAsync<TValue>(
            string storedProcedureLink,
            Documents.Client.RequestOptions options,
            IDocumentClientRetryPolicy retryPolicyInstance,
            CancellationToken cancellationToken,
            params dynamic[] procedureParams)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(storedProcedureLink))
            {
                throw new ArgumentNullException("storedProcedureLink");
            }

            JsonSerializerSettings serializerSettings = this.GetSerializerSettingsForRequest(options);
            string storedProcedureInput = serializerSettings == null ?
                JsonConvert.SerializeObject(procedureParams) :
                JsonConvert.SerializeObject(procedureParams, serializerSettings);
            using (MemoryStream storedProcedureInputStream = new MemoryStream())
            {
                using (StreamWriter writer = new StreamWriter(storedProcedureInputStream))
                {
                    await writer.WriteAsync(storedProcedureInput);
                    await writer.FlushAsync();
                    storedProcedureInputStream.Position = 0;

                    INameValueCollection headers = this.GetRequestHeaders(options, OperationType.ExecuteJavaScript, ResourceType.StoredProcedure);
                    using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                        OperationType.ExecuteJavaScript,
                        ResourceType.StoredProcedure,
                        storedProcedureLink,
                        storedProcedureInputStream,
                        AuthorizationTokenType.PrimaryMasterKey,
                        headers))
                    {
                        request.Headers[HttpConstants.HttpHeaders.XDate] = Rfc1123DateTimeCache.UtcNow();
                        if (options?.PartitionKeyRangeId == null)
                        {
                            await this.AddPartitionKeyInformationAsync(
                                request,
                                options);
                        }

                        retryPolicyInstance?.OnBeforeSendRequest(request);

                        request.SerializerSettings = this.GetSerializerSettingsForRequest(options);
                        return new StoredProcedureResponse<TValue>(await this.ExecuteProcedureAsync(
                            request,
                            retryPolicyInstance,
                            cancellationToken),
                            this.GetSerializerSettingsForRequest(options));
                    }
                }
            }
        }

        #endregion

        #region Upsert Impl
        /// <summary>
        /// Upserts a database resource as an asychronous operation in the Azure Cosmos DB service.
        /// </summary>
        /// <param name="database">The specification for the <see cref="Database"/> to upsert.</param>
        /// <param name="options">(Optional) The <see cref="Documents.Client.RequestOptions"/> for the request.</param>
        /// <returns>The <see cref="Database"/> that was upserted within a task object representing the service response for the asynchronous operation.</returns>
        /// <exception cref="ArgumentNullException">If <paramref name="database"/> is not set</exception>
        /// <exception cref="System.AggregateException">Represents a consolidation of failures that occured during async processing. Look within InnerExceptions to find the actual exception(s)</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Database are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>400</term><description>BadRequest - This means something was wrong with the database object supplied. It is likely that an id was not supplied for the new Database.</description>
        ///     </item>
        ///     <item>
        ///         <term>409</term><description>Conflict - This means a <see cref="Database"/> with an id matching the id field of <paramref name="database"/> already existed</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// The example below upserts a new <see cref="Database"/> with an Id property of 'MyDatabase'
        /// This code snippet is intended to be used from within an Asynchronous method as it uses the await keyword
        /// <code language="c#">
        /// <![CDATA[
        /// using (IDocumentClient client = new DocumentClient(new Uri("service endpoint"), "auth key"))
        /// {
        ///     Database db = await client.UpsertDatabaseAsync(new Database { Id = "MyDatabase" });
        /// }
        /// ]]>
        /// </code>
        ///
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.Database"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        internal Task<ResourceResponse<Documents.Database>> UpsertDatabaseAsync(Documents.Database database, Documents.Client.RequestOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(() => this.UpsertDatabasePrivateAsync(database, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<Documents.Database>> UpsertDatabasePrivateAsync(Documents.Database database, Documents.Client.RequestOptions options, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (database == null)
            {
                throw new ArgumentNullException("database");
            }

            this.ValidateResource(database);

            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Upsert, ResourceType.Database);

            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Upsert,
                Paths.Databases_Root,
                database,
                ResourceType.Database,
                AuthorizationTokenType.PrimaryMasterKey,
                headers,
                SerializationFormattingPolicy.None))
            {
                return new ResourceResponse<Documents.Database>(await this.UpsertAsync(request, retryPolicyInstance));
            }
        }

        /// <summary>
        /// Upserts a Document as an asychronous operation in the Azure Cosmos DB service.
        /// </summary>
        /// <param name="documentsFeedOrDatabaseLink">The link of the <see cref="DocumentCollection"/> to upsert the document in. E.g. dbs/db_rid/colls/coll_rid/ </param>
        /// <param name="document">The document object to upsert.</param>
        /// <param name="options">(Optional) Any request options you wish to set. E.g. Specifying a Trigger to execute when creating the document. <see cref="Documents.Client.RequestOptions"/></param>
        /// <param name="disableAutomaticIdGeneration">(Optional) Disables the automatic id generation, If this is True the system will throw an exception if the id property is missing from the Document.</param>
        /// <param name="cancellationToken">(Optional) A <see cref="CancellationToken"/> that can be used by other objects or threads to receive notice of cancellation.</param>
        /// <returns>The <see cref="Document"/> that was upserted contained within a <see cref="System.Threading.Tasks.Task"/> object representing the service response for the asynchronous operation.</returns>
        /// <exception cref="ArgumentNullException">If either <paramref name="documentsFeedOrDatabaseLink"/> or <paramref name="document"/> is not set.</exception>
        /// <exception cref="System.AggregateException">Represents a consolidation of failures that occured during async processing. Look within InnerExceptions to find the actual exception(s)</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>400</term><description>BadRequest - This means something was wrong with the document supplied. It is likely that <paramref name="disableAutomaticIdGeneration"/> was true and an id was not supplied</description>
        ///     </item>
        ///     <item>
        ///         <term>403</term><description>Forbidden - This likely means the collection in to which you were trying to upsert the document is full.</description>
        ///     </item>
        ///     <item>
        ///         <term>409</term><description>Conflict - This means a <see cref="Document"/> with an id matching the id field of <paramref name="document"/> already existed</description>
        ///     </item>
        ///     <item>
        ///         <term>413</term><description>RequestEntityTooLarge - This means the <see cref="Document"/> exceeds the current max entity size. Consult documentation for limits and quotas.</description>
        ///     </item>
        ///     <item>
        ///         <term>429</term><description>TooManyRequests - This means you have exceeded the number of request units per second. Consult the DocumentClientException.RetryAfter value to see how long you should wait before retrying this operation.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        /// Azure Cosmos DB supports a number of different ways to work with documents. A document can extend <see cref="Resource"/>
        /// <code language="c#">
        /// <![CDATA[
        /// public class MyObject : Resource
        /// {
        ///     public string MyProperty {get; set;}
        /// }
        ///
        /// using (IDocumentClient client = new DocumentClient(new Uri("service endpoint"), "auth key"))
        /// {
        ///     Document doc = await client.UpsertDocumentAsync("dbs/db_rid/colls/coll_rid/", new MyObject { MyProperty = "A Value" });
        /// }
        /// ]]>
        /// </code>
        /// </example>
        /// <example>
        /// A document can be any POCO object that can be serialized to JSON, even if it doesn't extend from <see cref="Resource"/>
        /// <code language="c#">
        /// <![CDATA[
        /// public class MyPOCO
        /// {
        ///     public string MyProperty {get; set;}
        /// }
        ///
        /// using (IDocumentClient client = new DocumentClient(new Uri("service endpoint"), "auth key"))
        /// {
        ///     Document doc = await client.UpsertDocumentAsync("dbs/db_rid/colls/coll_rid/", new MyPOCO { MyProperty = "A Value" });
        /// }
        /// ]]>
        /// </code>
        /// </example>
        /// <example>
        /// A Document can also be a dynamic object
        /// <code language="c#">
        /// <![CDATA[
        /// using (IDocumentClient client = new DocumentClient(new Uri("service endpoint"), "auth key"))
        /// {
        ///     Document doc = await client.UpsertDocumentAsync("dbs/db_rid/colls/coll_rid/", new { SomeProperty = "A Value" } );
        /// }
        /// ]]>
        /// </code>
        /// </example>
        /// <example>
        /// Upsert a Document and execute a Pre and Post Trigger
        /// <code language="c#">
        /// <![CDATA[
        /// using (IDocumentClient client = new DocumentClient(new Uri("service endpoint"), "auth key"))
        /// {
        ///     Document doc = await client.UpsertDocumentAsync(
        ///         "dbs/db_rid/colls/coll_rid/",
        ///         new { id = "DOC123213443" },
        ///         new RequestOptions
        ///         {
        ///             PreTriggerInclude = new List<string> { "MyPreTrigger" },
        ///             PostTriggerInclude = new List<string> { "MyPostTrigger" }
        ///         });
        /// }
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.Document"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<ResourceResponse<Document>> UpsertDocumentAsync(string documentsFeedOrDatabaseLink, object document, Documents.Client.RequestOptions options = null, bool disableAutomaticIdGeneration = false, CancellationToken cancellationToken = default)
        {
            // This call is to just run UpsertDocumentInlineAsync in a SynchronizationContext aware environment
            return TaskHelper.InlineIfPossible(() => this.UpsertDocumentInlineAsync(documentsFeedOrDatabaseLink, document, options, disableAutomaticIdGeneration, cancellationToken), null, cancellationToken);
        }

        private async Task<ResourceResponse<Document>> UpsertDocumentInlineAsync(string documentsFeedOrDatabaseLink, object document, Documents.Client.RequestOptions options, bool disableAutomaticIdGeneration, CancellationToken cancellationToken)
        {
            IDocumentClientRetryPolicy requestRetryPolicy = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            if (options?.PartitionKey == null)
            {
                requestRetryPolicy = new PartitionKeyMismatchRetryPolicy(
                    await this.GetCollectionCacheAsync(NoOpTrace.Singleton), 
                    requestRetryPolicy);
            }

            return await TaskHelper.InlineIfPossible(() => this.UpsertDocumentPrivateAsync(
                documentsFeedOrDatabaseLink,
                document,
                options,
                disableAutomaticIdGeneration,
                requestRetryPolicy,
                cancellationToken), requestRetryPolicy, cancellationToken);
        }

        private async Task<ResourceResponse<Document>> UpsertDocumentPrivateAsync(
            string documentCollectionLink,
            object document,
            Documents.Client.RequestOptions options,
            bool disableAutomaticIdGeneration,
            IDocumentClientRetryPolicy retryPolicyInstance,
            CancellationToken cancellationToken)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(documentCollectionLink))
            {
                throw new ArgumentNullException("documentCollectionLink");
            }

            if (document == null)
            {
                throw new ArgumentNullException("document");
            }

            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Upsert, ResourceType.Document);
            Document typedDocument = Document.FromObject(document, this.GetSerializerSettingsForRequest(options));
            this.ValidateResource(typedDocument);

            if (string.IsNullOrEmpty(typedDocument.Id) && !disableAutomaticIdGeneration)
            {
                typedDocument.Id = Guid.NewGuid().ToString();
            }

            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Upsert,
                documentCollectionLink,
                typedDocument,
                ResourceType.Document,
                AuthorizationTokenType.PrimaryMasterKey,
                headers,
                SerializationFormattingPolicy.None,
                this.GetSerializerSettingsForRequest(options)))
            {
                await this.AddPartitionKeyInformationAsync(request, typedDocument, options);

                return new ResourceResponse<Document>(await this.UpsertAsync(request, retryPolicyInstance, cancellationToken));
            }
        }

        /// <summary>
        /// Upserts a collection as an asychronous operation in the Azure Cosmos DB service.
        /// </summary>
        /// <param name="databaseLink">The link of the database to upsert the collection in. E.g. dbs/db_rid/</param>
        /// <param name="documentCollection">The <see cref="Microsoft.Azure.Documents.DocumentCollection"/> object.</param>
        /// <param name="options">(Optional) Any <see cref="Microsoft.Azure.Documents.Client.RequestOptions"/> you wish to provide when creating a Collection. E.g. RequestOptions.OfferThroughput = 400. </param>
        /// <returns>The <see cref="Microsoft.Azure.Documents.DocumentCollection"/> that was upserted contained within a <see cref="System.Threading.Tasks.Task"/> object representing the service response for the asynchronous operation.</returns>
        /// <exception cref="ArgumentNullException">If either <paramref name="databaseLink"/> or <paramref name="documentCollection"/> is not set.</exception>
        /// <exception cref="System.AggregateException">Represents a consolidation of failures that occured during async processing. Look within InnerExceptions to find the actual exception(s)</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>400</term><description>BadRequest - This means something was wrong with the request supplied. It is likely that an id was not supplied for the new collection.</description>
        ///     </item>
        ///     <item>
        ///         <term>403</term><description>Forbidden - This means you attempted to exceed your quota for collections. Contact support to have this quota increased.</description>
        ///     </item>
        ///     <item>
        ///         <term>409</term><description>Conflict - This means a <see cref="Microsoft.Azure.Documents.DocumentCollection"/> with an id matching the id you supplied already existed.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        ///
        /// <code language="c#">
        /// <![CDATA[
        /// using (IDocumentClient client = new DocumentClient(new Uri("service endpoint"), "auth key"))
        /// {
        ///     //Upsert a new collection with an OfferThroughput set to 10000
        ///     //Not passing in RequestOptions.OfferThroughput will result in a collection with the default OfferThroughput set.
        ///     DocumentCollection coll = await client.UpsertDocumentCollectionAsync(databaseLink,
        ///         new DocumentCollection { Id = "My Collection" },
        ///         new RequestOptions { OfferThroughput = 10000} );
        /// }
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.DocumentCollection"/>
        /// <seealso cref="Microsoft.Azure.Documents.Offer"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        internal Task<ResourceResponse<DocumentCollection>> UpsertDocumentCollectionAsync(string databaseLink, DocumentCollection documentCollection, Documents.Client.RequestOptions options = null)
        {
            // To be implemented.
            throw new NotImplementedException();
        }

        /// <summary>
        /// Upserts a stored procedure as an asychronous operation in the Azure Cosmos DB service.
        /// </summary>
        /// <param name="collectionLink">The link of the collection to upsert the stored procedure in. E.g. dbs/db_rid/colls/col_rid/</param>
        /// <param name="storedProcedure">The <see cref="Microsoft.Azure.Documents.StoredProcedure"/> object to upsert.</param>
        /// <param name="options">(Optional) Any <see cref="Microsoft.Azure.Documents.Client.RequestOptions"/>for this request.</param>
        /// <returns>The <see cref="Microsoft.Azure.Documents.StoredProcedure"/> that was upserted contained within a <see cref="System.Threading.Tasks.Task"/> object representing the service response for the asynchronous operation.</returns>
        /// <exception cref="ArgumentNullException">If either <paramref name="collectionLink"/> or <paramref name="storedProcedure"/> is not set.</exception>
        /// <exception cref="System.AggregateException">Represents a consolidation of failures that occured during async processing. Look within InnerExceptions to find the actual exception(s)</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>400</term><description>BadRequest - This means something was wrong with the request supplied. It is likely that an Id was not supplied for the stored procedure or the Body was malformed.</description>
        ///     </item>
        ///     <item>
        ///         <term>403</term><description>Forbidden - You have reached your quota of stored procedures for the collection supplied. Contact support to have this quota increased.</description>
        ///     </item>
        ///     <item>
        ///         <term>409</term><description>Conflict - This means a <see cref="Microsoft.Azure.Documents.StoredProcedure"/> with an id matching the id you supplied already existed.</description>
        ///     </item>
        ///     <item>
        ///         <term>413</term><description>RequestEntityTooLarge - This means the body of the <see cref="Microsoft.Azure.Documents.StoredProcedure"/> you tried to upsert was too large.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        ///
        /// <code language="c#">
        /// <![CDATA[
        /// //Upsert a new stored procedure called "HelloWorldSproc" that takes in a single param called "name".
        /// StoredProcedure sproc = await client.UpsertStoredProcedureAsync(collectionLink, new StoredProcedure
        /// {
        ///    Id = "HelloWorldSproc",
        ///    Body = @"function (name){
        ///                var response = getContext().getResponse();
        ///                response.setBody('Hello ' + name);
        ///             }"
        /// });
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.StoredProcedure"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<ResourceResponse<StoredProcedure>> UpsertStoredProcedureAsync(string collectionLink, StoredProcedure storedProcedure, Documents.Client.RequestOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(() => this.UpsertStoredProcedurePrivateAsync(collectionLink, storedProcedure, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<StoredProcedure>> UpsertStoredProcedurePrivateAsync(
            string collectionLink,
            StoredProcedure storedProcedure,
            Documents.Client.RequestOptions options,
            IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(collectionLink))
            {
                throw new ArgumentNullException("collectionLink");
            }

            if (storedProcedure == null)
            {
                throw new ArgumentNullException("storedProcedure");
            }

            this.ValidateResource(storedProcedure);

            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Upsert, ResourceType.StoredProcedure);
            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Upsert,
                collectionLink,
                storedProcedure,
                ResourceType.StoredProcedure,
                AuthorizationTokenType.PrimaryMasterKey,
                headers,
                SerializationFormattingPolicy.None))
            {
                return new ResourceResponse<StoredProcedure>(await this.UpsertAsync(request, retryPolicyInstance));
            }
        }

        /// <summary>
        /// Upserts a trigger as an asychronous operation in the Azure Cosmos DB service.
        /// </summary>
        /// <param name="collectionLink">The link of the <see cref="Microsoft.Azure.Documents.DocumentCollection"/> to upsert the trigger in. E.g. dbs/db_rid/colls/col_rid/ </param>
        /// <param name="trigger">The <see cref="Microsoft.Azure.Documents.Trigger"/> object to upsert.</param>
        /// <param name="options">(Optional) Any <see cref="Microsoft.Azure.Documents.Client.RequestOptions"/>for this request.</param>
        /// <returns>A task object representing the service response for the asynchronous operation.</returns>
        /// <exception cref="ArgumentNullException">If either <paramref name="collectionLink"/> or <paramref name="trigger"/> is not set.</exception>
        /// <exception cref="System.AggregateException">Represents a consolidation of failures that occured during async processing. Look within InnerExceptions to find the actual exception(s)</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>400</term><description>BadRequest - This means something was wrong with the request supplied. It is likely that an Id was not supplied for the new trigger or that the Body was malformed.</description>
        ///     </item>
        ///     <item>
        ///         <term>403</term><description>Forbidden - You have reached your quota of triggers for the collection supplied. Contact support to have this quota increased.</description>
        ///     </item>
        ///     <item>
        ///         <term>409</term><description>Conflict - This means a <see cref="Microsoft.Azure.Documents.Trigger"/> with an id matching the id you supplied already existed.</description>
        ///     </item>
        ///     <item>
        ///         <term>413</term><description>RequestEntityTooLarge - This means the body of the <see cref="Microsoft.Azure.Documents.Trigger"/> you tried to upsert was too large.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        ///
        /// <code language="c#">
        /// <![CDATA[
        /// //Upsert a trigger that validates the contents of a document as it is created and adds a 'timestamp' property if one was not found.
        /// Trigger trig = await client.UpsertTriggerAsync(collectionLink, new Trigger
        /// {
        ///     Id = "ValidateDocuments",
        ///     Body = @"function validate() {
        ///                         var context = getContext();
        ///                         var request = context.getRequest();                                                             
        ///                         var documentToCreate = request.getBody();
        ///                         
        ///                         // validate properties
        ///                         if (!('timestamp' in documentToCreate)) {
        ///                             var ts = new Date();
        ///                             documentToCreate['timestamp'] = ts.getTime();
        ///                         }
        ///                         
        ///                         // update the document that will be created
        ///                         request.setBody(documentToCreate);
        ///                       }",
        ///     TriggerType = TriggerType.Pre,
        ///     TriggerOperation = TriggerOperation.Create
        /// });
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.Trigger"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<ResourceResponse<Trigger>> UpsertTriggerAsync(string collectionLink, Trigger trigger, Documents.Client.RequestOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(() => this.UpsertTriggerPrivateAsync(collectionLink, trigger, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<Trigger>> UpsertTriggerPrivateAsync(string collectionLink, Trigger trigger, Documents.Client.RequestOptions options, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(collectionLink))
            {
                throw new ArgumentNullException("collectionLink");
            }

            if (trigger == null)
            {
                throw new ArgumentNullException("trigger");
            }

            this.ValidateResource(trigger);
            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Upsert, ResourceType.Trigger);
            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Upsert,
                collectionLink,
                trigger,
                ResourceType.Trigger,
                AuthorizationTokenType.PrimaryMasterKey,
                headers,
                SerializationFormattingPolicy.None))
            {
                return new ResourceResponse<Trigger>(await this.UpsertAsync(request, retryPolicyInstance));
            }
        }

        /// <summary>
        /// Upserts a user defined function as an asychronous operation in the Azure Cosmos DB service.
        /// </summary>
        /// <param name="collectionLink">The link of the <see cref="Microsoft.Azure.Documents.DocumentCollection"/> to upsert the user defined function in. E.g. dbs/db_rid/colls/col_rid/ </param>
        /// <param name="function">The <see cref="Microsoft.Azure.Documents.UserDefinedFunction"/> object to upsert.</param>
        /// <param name="options">(Optional) Any <see cref="Microsoft.Azure.Documents.Client.RequestOptions"/>for this request.</param>
        /// <returns>A task object representing the service response for the asynchronous operation.</returns>
        /// <exception cref="ArgumentNullException">If either <paramref name="collectionLink"/> or <paramref name="function"/> is not set.</exception>
        /// <exception cref="System.AggregateException">Represents a consolidation of failures that occured during async processing. Look within InnerExceptions to find the actual exception(s)</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>400</term><description>BadRequest - This means something was wrong with the request supplied. It is likely that an Id was not supplied for the new user defined function or that the Body was malformed.</description>
        ///     </item>
        ///     <item>
        ///         <term>403</term><description>Forbidden - You have reached your quota of user defined functions for the collection supplied. Contact support to have this quota increased.</description>
        ///     </item>
        ///     <item>
        ///         <term>409</term><description>Conflict - This means a <see cref="Microsoft.Azure.Documents.UserDefinedFunction"/> with an id matching the id you supplied already existed.</description>
        ///     </item>
        ///     <item>
        ///         <term>413</term><description>RequestEntityTooLarge - This means the body of the <see cref="Microsoft.Azure.Documents.UserDefinedFunction"/> you tried to upsert was too large.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        ///
        /// <code language="c#">
        /// <![CDATA[
        /// //Upsert a user defined function that converts a string to upper case
        /// UserDefinedFunction udf = client.UpsertUserDefinedFunctionAsync(collectionLink, new UserDefinedFunction
        /// {
        ///    Id = "ToUpper",
        ///    Body = @"function toUpper(input) {
        ///                        return input.toUpperCase();
        ///                     }",
        /// });
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.UserDefinedFunction"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        public Task<ResourceResponse<UserDefinedFunction>> UpsertUserDefinedFunctionAsync(string collectionLink, UserDefinedFunction function, Documents.Client.RequestOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(() => this.UpsertUserDefinedFunctionPrivateAsync(collectionLink, function, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<UserDefinedFunction>> UpsertUserDefinedFunctionPrivateAsync(
            string collectionLink,
            UserDefinedFunction function,
            Documents.Client.RequestOptions options,
            IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(collectionLink))
            {
                throw new ArgumentNullException("collectionLink");
            }

            if (function == null)
            {
                throw new ArgumentNullException("function");
            }

            this.ValidateResource(function);
            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Upsert, ResourceType.UserDefinedFunction);
            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Upsert,
                collectionLink,
                function,
                ResourceType.UserDefinedFunction,
                AuthorizationTokenType.PrimaryMasterKey,
                headers,
                SerializationFormattingPolicy.None))
            {
                return new ResourceResponse<UserDefinedFunction>(await this.UpsertAsync(request, retryPolicyInstance));
            }
        }

        /// <summary>
        /// Upserts a user defined type object in the Azure Cosmos DB service as an asychronous operation.
        /// </summary>
        /// <param name="databaseLink">The link of the database to upsert the user defined type in. E.g. dbs/db_rid/ </param>
        /// <param name="userDefinedType">The <see cref="Microsoft.Azure.Documents.UserDefinedType"/> object to upsert.</param>
        /// <param name="options">(Optional) The request options for the request.</param>
        /// <returns>A task object representing the service response for the asynchronous operation which contains the upserted <see cref="Microsoft.Azure.Documents.UserDefinedType"/> object.</returns>
        /// <exception cref="ArgumentNullException">If either <paramref name="databaseLink"/> or <paramref name="userDefinedType"/> is not set.</exception>
        /// <exception cref="System.AggregateException">Represents a consolidation of failures that occured during async processing. Look within InnerExceptions to find the actual exception(s)</exception>
        /// <exception cref="DocumentClientException">This exception can encapsulate many different types of errors. To determine the specific error always look at the StatusCode property. Some common codes you may get when creating a Document are:
        /// <list type="table">
        ///     <listheader>
        ///         <term>StatusCode</term><description>Reason for exception</description>
        ///     </listheader>
        ///     <item>
        ///         <term>400</term><description>BadRequest - This means something was wrong with the request supplied.</description>
        ///     </item>
        ///     <item>
        ///         <term>403</term><description>Forbidden - You have reached your quota of user defined type objects for this database. Contact support to have this quota increased.</description>
        ///     </item>
        ///     <item>
        ///         <term>409</term><description>Conflict - This means a <see cref="Microsoft.Azure.Documents.UserDefinedType"/> with an id matching the id you supplied already existed.</description>
        ///     </item>
        /// </list>
        /// </exception>
        /// <example>
        ///
        /// <code language="c#">
        /// <![CDATA[
        /// //Upsert a new user defined type in the specified database
        /// UserDefinedType userDefinedType = await client.UpsertUserDefinedTypeAsync(databaseLink, new UserDefinedType { Id = "userDefinedTypeId5" });
        /// ]]>
        /// </code>
        /// </example>
        /// <seealso cref="Microsoft.Azure.Documents.UserDefinedType"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.RequestOptions"/>
        /// <seealso cref="Microsoft.Azure.Documents.Client.ResourceResponse{T}"/>
        /// <seealso cref="System.Threading.Tasks.Task"/>
        internal Task<ResourceResponse<UserDefinedType>> UpsertUserDefinedTypeAsync(string databaseLink, UserDefinedType userDefinedType, Documents.Client.RequestOptions options = null)
        {
            IDocumentClientRetryPolicy retryPolicyInstance = this.ResetSessionTokenRetryPolicy.GetRequestPolicy();
            return TaskHelper.InlineIfPossible(() => this.UpsertUserDefinedTypePrivateAsync(databaseLink, userDefinedType, options, retryPolicyInstance), retryPolicyInstance);
        }

        private async Task<ResourceResponse<UserDefinedType>> UpsertUserDefinedTypePrivateAsync(string databaseLink, UserDefinedType userDefinedType, Documents.Client.RequestOptions options, IDocumentClientRetryPolicy retryPolicyInstance)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);

            if (string.IsNullOrEmpty(databaseLink))
            {
                throw new ArgumentNullException("databaseLink");
            }

            if (userDefinedType == null)
            {
                throw new ArgumentNullException("userDefinedType");
            }

            this.ValidateResource(userDefinedType);
            INameValueCollection headers = this.GetRequestHeaders(options, OperationType.Upsert, ResourceType.UserDefinedType);
            using (DocumentServiceRequest request = DocumentServiceRequest.Create(
                OperationType.Upsert,
                databaseLink,
                userDefinedType,
                ResourceType.UserDefinedType,
                AuthorizationTokenType.PrimaryMasterKey,
                headers,
                SerializationFormattingPolicy.None))
            {
                return new ResourceResponse<UserDefinedType>(await this.UpsertAsync(request, retryPolicyInstance));
            }
        }
        #endregion

        #region IAuthorizationTokenProvider

        ValueTask<(string token, string payload)> IAuthorizationTokenProvider.GetUserAuthorizationAsync(
            string resourceAddress,
            string resourceType,
            string requestVerb,
            INameValueCollection headers,
            AuthorizationTokenType tokenType)
        {
            return this.cosmosAuthorization.GetUserAuthorizationAsync(
                resourceAddress,
                resourceType,
                requestVerb,
                headers,
                tokenType);
        }

        ValueTask<string> ICosmosAuthorizationTokenProvider.GetUserAuthorizationTokenAsync(
            string resourceAddress,
            string resourceType,
            string requestVerb,
            INameValueCollection headers,
            AuthorizationTokenType tokenType,
            ITrace trace)
        {
            return this.cosmosAuthorization.GetUserAuthorizationTokenAsync(
                resourceAddress,
                resourceType,
                requestVerb,
                headers,
                tokenType,
                trace);
        }

        Task IAuthorizationTokenProvider.AddSystemAuthorizationHeaderAsync(
            DocumentServiceRequest request,
            string federationId,
            string verb,
            string resourceId)
        {
            return this.cosmosAuthorization.AddSystemAuthorizationHeaderAsync(
                request,
                federationId,
                verb,
                resourceId);
        }

        #endregion

        #region Core Implementation
        internal Task<DocumentServiceResponse> CreateAsync(
            DocumentServiceRequest request,
            IDocumentClientRetryPolicy retryPolicy,
            CancellationToken cancellationToken = default)
        {
            if (request == null)
            {
                throw new ArgumentNullException("request");
            }

            return this.ProcessRequestAsync(HttpConstants.HttpMethods.Post, request, retryPolicy, cancellationToken);
        }

        internal Task<DocumentServiceResponse> UpdateAsync(
            DocumentServiceRequest request,
            IDocumentClientRetryPolicy retryPolicy,
            CancellationToken cancellationToken = default)
        {
            if (request == null)
            {
                throw new ArgumentNullException("request");
            }

            return this.ProcessRequestAsync(HttpConstants.HttpMethods.Put, request, retryPolicy, cancellationToken);
        }

        internal Task<DocumentServiceResponse> ReadAsync(
            DocumentServiceRequest request,
            IDocumentClientRetryPolicy retryPolicy,
            CancellationToken cancellationToken = default)
        {
            if (request == null)
            {
                throw new ArgumentNullException("request");
            }

            return this.ProcessRequestAsync(HttpConstants.HttpMethods.Get, request, retryPolicy, cancellationToken);
        }

        internal Task<DocumentServiceResponse> ReadFeedAsync(
            DocumentServiceRequest request,
            IDocumentClientRetryPolicy retryPolicy,
            CancellationToken cancellationToken = default)
        {
            if (request == null)
            {
                throw new ArgumentNullException("request");
            }

            return this.ProcessRequestAsync(HttpConstants.HttpMethods.Get, request, retryPolicy, cancellationToken);
        }

        internal Task<DocumentServiceResponse> DeleteAsync(
            DocumentServiceRequest request,
            IDocumentClientRetryPolicy retryPolicy,
            CancellationToken cancellationToken = default)
        {
            if (request == null)
            {
                throw new ArgumentNullException("request");
            }

            return this.ProcessRequestAsync(HttpConstants.HttpMethods.Delete, request, retryPolicy, cancellationToken);
        }

        internal Task<DocumentServiceResponse> ExecuteProcedureAsync(
            DocumentServiceRequest request,
            IDocumentClientRetryPolicy retryPolicy,
            CancellationToken cancellationToken = default)
        {
            if (request == null)
            {
                throw new ArgumentNullException("request");
            }

            return this.ProcessRequestAsync(HttpConstants.HttpMethods.Post, request, retryPolicy, cancellationToken);
        }

        internal Task<DocumentServiceResponse> ExecuteQueryAsync(
            DocumentServiceRequest request,
            IDocumentClientRetryPolicy retryPolicy,
            CancellationToken cancellationToken = default)
        {
            if (request == null)
            {
                throw new ArgumentNullException("request");
            }

            return this.ProcessRequestAsync(HttpConstants.HttpMethods.Post, request, retryPolicy, cancellationToken);
        }

        internal Task<DocumentServiceResponse> UpsertAsync(
            DocumentServiceRequest request,
            IDocumentClientRetryPolicy retryPolicy,
            CancellationToken cancellationToken = default)
        {
            if (request == null)
            {
                throw new ArgumentNullException("request");
            }

            request.Headers[HttpConstants.HttpHeaders.IsUpsert] = bool.TrueString;
            return this.ProcessRequestAsync(HttpConstants.HttpMethods.Post, request, retryPolicy, cancellationToken);
        }
        #endregion

        /// <summary>
        /// Read the <see cref="AccountProperties"/> from the Azure Cosmos DB service as an asynchronous operation.
        /// </summary>
        /// <returns>
        /// A <see cref="AccountProperties"/> wrapped in a <see cref="System.Threading.Tasks.Task"/> object.
        /// </returns>
        public Task<AccountProperties> GetDatabaseAccountAsync()
        {
            return TaskHelper.InlineIfPossible(() => this.GetDatabaseAccountPrivateAsync(this.ReadEndpoint), this.ResetSessionTokenRetryPolicy.GetRequestPolicy());
        }

        /// <summary>
        /// Read the <see cref="AccountProperties"/> as an asynchronous operation
        /// given a specific reginal endpoint url.
        /// </summary>
        /// <param name="serviceEndpoint">The reginal url of the serice endpoint.</param>
        /// <param name="cancellationToken">The CancellationToken</param>
        /// <returns>
        /// A <see cref="AccountProperties"/> wrapped in a <see cref="System.Threading.Tasks.Task"/> object.
        /// </returns>
        Task<AccountProperties> IDocumentClientInternal.GetDatabaseAccountInternalAsync(Uri serviceEndpoint, CancellationToken cancellationToken)
        {
            return this.GetDatabaseAccountPrivateAsync(serviceEndpoint, cancellationToken);
        }

        private async Task<AccountProperties> GetDatabaseAccountPrivateAsync(Uri serviceEndpoint, CancellationToken cancellationToken = default)
        {
            await this.EnsureValidClientAsync(NoOpTrace.Singleton);
            if (this.GatewayStoreModel is GatewayStoreModel gatewayModel)
            {
                async ValueTask<HttpRequestMessage> CreateRequestMessage()
                {
                    HttpRequestMessage request = new HttpRequestMessage
                    {
                        Method = HttpMethod.Get,
                        RequestUri = serviceEndpoint
                    };

                    INameValueCollection headersCollection = new StoreResponseNameValueCollection();
                    await this.cosmosAuthorization.AddAuthorizationHeaderAsync(
                        headersCollection,
                        serviceEndpoint,
                        "GET",
                        AuthorizationTokenType.PrimaryMasterKey);

                    foreach (string key in headersCollection.AllKeys())
                    {
                        request.Headers.Add(key, headersCollection[key]);
                    }

                    return request;
                }

                AccountProperties databaseAccount = await gatewayModel.GetDatabaseAccountAsync(CreateRequestMessage,
                                                                                               clientSideRequestStatistics: null);
                this.UseMultipleWriteLocations = this.ConnectionPolicy.UseMultipleWriteLocations && databaseAccount.EnableMultipleWriteLocations;

                if (this.queryPartitionProvider.IsValueCreated)
                {
                    (await this.QueryPartitionProvider).Update(databaseAccount.QueryEngineConfiguration);
                }

                return databaseAccount;
            }

            return null;
        }

        #region Private Impl

        /// <summary>
        /// Certain requests must be routed through gateway even when the client connectivity mode is direct.
        /// For e.g., DocumentCollection creation. This method returns the <see cref="IStoreModel"/> based
        /// on the input <paramref name="request"/>.
        /// </summary>
        /// <returns>Returns <see cref="IStoreModel"/> to which the request must be sent</returns>
        internal IStoreModel GetStoreProxy(DocumentServiceRequest request)
        {
            // If a request is configured to always use Gateway mode(in some cases when targeting .NET Core)
            // we return the Gateway store model
            if (request.UseGatewayMode)
            {
                return this.GatewayStoreModel;
            }

            ResourceType resourceType = request.ResourceType;
            OperationType operationType = request.OperationType;

            if (resourceType == ResourceType.Offer ||
                (resourceType.IsScript() && operationType != OperationType.ExecuteJavaScript) ||
                resourceType == ResourceType.PartitionKeyRange ||
                resourceType == ResourceType.Snapshot ||
                resourceType == ResourceType.ClientEncryptionKey ||
                (resourceType == ResourceType.PartitionKey && operationType == OperationType.Delete))
            {
                return this.GatewayStoreModel;
            }

            if (operationType == OperationType.Create
                || operationType == OperationType.Upsert)
            {
                if (resourceType == ResourceType.Database ||
                    resourceType == ResourceType.User ||
                    resourceType == ResourceType.Collection ||
                    resourceType == ResourceType.Permission)
                {
                    return this.GatewayStoreModel;
                }
                else
                {
                    return this.StoreModel;
                }
            }
            else if (operationType == OperationType.Delete)
            {
                if (resourceType == ResourceType.Database ||
                    resourceType == ResourceType.User ||
                    resourceType == ResourceType.Collection)
                {
                    return this.GatewayStoreModel;
                }
                else
                {
                    return this.StoreModel;
                }
            }
            else if ((operationType == OperationType.Replace) || (operationType == OperationType.CollectionTruncate))
            {
                if (resourceType == ResourceType.Collection)
                {
                    return this.GatewayStoreModel;
                }
                else
                {
                    return this.StoreModel;
                }
            }
            else if (operationType == OperationType.Read)
            {
                if (resourceType == ResourceType.Collection)
                {
                    return this.GatewayStoreModel;
                }
                else
                {
                    return this.StoreModel;
                }
            }
            else
            {
                return this.StoreModel;
            }
        }

        /// <summary>
        /// The preferred link used in replace operation in SDK.
        /// </summary>
        private string GetLinkForRouting(Documents.Resource resource)
        {
            // we currently prefer the selflink
            return resource.SelfLink ?? resource.AltLink;
        }

        internal void EnsureValidOverwrite(
            Documents.ConsistencyLevel desiredConsistencyLevel,
            OperationType? operationType = null,
            ResourceType? resourceType = null)
        {
            Documents.ConsistencyLevel defaultConsistencyLevel = this.accountServiceConfiguration.DefaultConsistencyLevel;
            if (!this.IsValidConsistency(
                        defaultConsistencyLevel, 
                        desiredConsistencyLevel,
                        operationType,
                        resourceType))
            {
                throw new ArgumentException(string.Format(
                    CultureInfo.CurrentUICulture,
                    RMResources.InvalidConsistencyLevel,
                    desiredConsistencyLevel.ToString(),
                    defaultConsistencyLevel.ToString()));
            }
        }

        private bool IsValidConsistency(
            Documents.ConsistencyLevel backendConsistency, 
            Documents.ConsistencyLevel desiredConsistency,
            OperationType? operationType,
            ResourceType? resourceType)
        {
            if (this.allowOverrideStrongerConsistency)
            {
                return true;
            }

            return ValidationHelpers.IsValidConsistencyLevelOverwrite(
                backendConsistency: backendConsistency,
                desiredConsistency: desiredConsistency,
                isLocalQuorumConsistency: this.IsLocalQuorumConsistency,
                operationType: operationType,
                resourceType: resourceType);
        }

        private void InitializeDirectConnectivity(IStoreClientFactory storeClientFactory)
        {
            this.AddressResolver = new GlobalAddressResolver(
                this.GlobalEndpointManager,
                this.PartitionKeyRangeLocation,
                this.ConnectionPolicy.ConnectionProtocol,
                this,
                this.collectionCache,
                this.partitionKeyRangeCache,
                this.accountServiceConfiguration,
                this.ConnectionPolicy,
                this.httpClient);

            // Check if we have a store client factory in input and if we do, do not initialize another store client
            // The purpose is to reuse store client factory across all document clients inside compute gateway
            if (storeClientFactory != null)
            {
                this.storeClientFactory = storeClientFactory;
                this.isStoreClientFactoryCreatedInternally = false;
            }
            else
            {
                Documents.Telemetry.DistributedTracingOptions distributedTracingOptions = new ()
                {
                    IsDistributedTracingEnabled = this.isDistributedTracingEnabled
                };

                StoreClientFactory newClientFactory = new StoreClientFactory(
                    this.ConnectionPolicy.ConnectionProtocol,
                    (int)this.ConnectionPolicy.RequestTimeout.TotalSeconds,
                    this.maxConcurrentConnectionOpenRequests,
                    this.ConnectionPolicy.UserAgentContainer,
                    this.eventSource,
                    null,
                    this.openConnectionTimeoutInSeconds,
                    this.idleConnectionTimeoutInSeconds,
                    this.timerPoolGranularityInSeconds,
                    this.maxRntbdChannels,
                    this.rntbdPartitionCount,
                    this.maxRequestsPerRntbdChannel,
                    (Documents.PortReuseMode)this.rntbdPortReuseMode,
                    this.rntbdPortPoolReuseThreshold,
                    this.rntbdPortPoolBindAttempts,
                    receiveHangDetectionTimeSeconds: this.rntbdReceiveHangDetectionTimeSeconds,
                    sendHangDetectionTimeSeconds: this.rntbdSendHangDetectionTimeSeconds,
                    retryWithConfiguration: this.ConnectionPolicy.RetryOptions?.GetRetryWithConfiguration(),
                    enableTcpConnectionEndpointRediscovery: this.ConnectionPolicy.EnableTcpConnectionEndpointRediscovery,
                    addressResolver: this.AddressResolver,
                    rntbdMaxConcurrentOpeningConnectionCount: this.rntbdMaxConcurrentOpeningConnectionCount,
                    remoteCertificateValidationCallback: this.remoteCertificateValidationCallback,
                    distributedTracingOptions: distributedTracingOptions);

                if (this.transportClientHandlerFactory != null)
                {
                    newClientFactory.WithTransportInterceptor(this.transportClientHandlerFactory);
                }

                this.storeClientFactory = newClientFactory;
                this.isStoreClientFactoryCreatedInternally = true;
            }

            this.CreateStoreModel(subscribeRntbdStatus: true);
        }

        private void CreateStoreModel(bool subscribeRntbdStatus)
        {
            //EnableReadRequestsFallback, if not explicity set on the connection policy,
            //is false if the account's consistency is bounded staleness,
            //and true otherwise.
            StoreClient storeClient = this.storeClientFactory.CreateStoreClient(
                this.AddressResolver,
                this.sessionContainer,
                this.accountServiceConfiguration,
                this,
                true,
                this.ConnectionPolicy.EnableReadRequestsFallback ?? (this.accountServiceConfiguration.DefaultConsistencyLevel != Documents.ConsistencyLevel.BoundedStaleness),
                !this.enableRntbdChannel,
                this.UseMultipleWriteLocations && (this.accountServiceConfiguration.DefaultConsistencyLevel != Documents.ConsistencyLevel.Strong),
                true,
                enableReplicaValidation: this.isReplicaAddressValidationEnabled);

            if (subscribeRntbdStatus)
            {
                storeClient.AddDisableRntbdChannelCallback(new Action(this.DisableRntbdChannel));
            }

            storeClient.SerializerSettings = this.serializerSettings;

            this.StoreModel = new ServerStoreModel(storeClient, this.sendingRequest, this.receivedResponse);
        }

        private void DisableRntbdChannel()
        {
            Debug.Assert(this.enableRntbdChannel);
            this.enableRntbdChannel = false;
            this.CreateStoreModel(subscribeRntbdStatus: false);
        }

        private async Task InitializeGatewayConfigurationReaderAsync()
        {
            GatewayAccountReader accountReader = new GatewayAccountReader(
                    serviceEndpoint: this.ServiceEndpoint,
                    cosmosAuthorization: this.cosmosAuthorization,
                    connectionPolicy: this.ConnectionPolicy,
                    httpClient: this.httpClient,
                    cancellationToken: this.cancellationTokenSource.Token);

            this.accountServiceConfiguration = new CosmosAccountServiceConfiguration(accountReader.InitializeReaderAsync);

            await this.accountServiceConfiguration.InitializeAsync();
            AccountProperties accountProperties = this.accountServiceConfiguration.AccountProperties;
            this.UseMultipleWriteLocations = this.ConnectionPolicy.UseMultipleWriteLocations && accountProperties.EnableMultipleWriteLocations;

            this.GlobalEndpointManager.InitializeAccountPropertiesAndStartBackgroundRefresh(accountProperties);
        }

        internal void CaptureSessionToken(DocumentServiceRequest request, DocumentServiceResponse response)
        {
            this.sessionContainer.SetSessionToken(request, response.Headers);
        }

        internal DocumentServiceRequest CreateDocumentServiceRequest(
            OperationType operationType,
            string resourceLink,
            ResourceType resourceType,
            INameValueCollection headers)
        {
            if (resourceType == ResourceType.Database || resourceType == ResourceType.Offer)
            {
                return DocumentServiceRequest.Create(
                    operationType,
                    null,
                    resourceType,
                    AuthorizationTokenType.PrimaryMasterKey,
                    headers);
            }
            else
            {
                return DocumentServiceRequest.Create(
                    operationType,
                    resourceType,
                    resourceLink,
                    AuthorizationTokenType.PrimaryMasterKey,
                    headers);
            }
        }

        internal void ValidateResource(Documents.Resource resource)
        {
            this.ValidateResource(resource.Id);
        }

        internal void ValidateResource(string resourceId)
        {
            if (!string.IsNullOrEmpty(resourceId))
            {
                int match = resourceId.IndexOfAny(new char[] { '/', '\\', '?', '#' });
                if (match != -1)
                {
                    throw new ArgumentException(string.Format(
                                CultureInfo.CurrentUICulture,
                                RMResources.InvalidCharacterInResourceName,
                                resourceId[match]));
                }

                if (resourceId[resourceId.Length - 1] == ' ')
                {
                    throw new ArgumentException(RMResources.InvalidSpaceEndingInResourceName);
                }
            }
        }

        private async Task AddPartitionKeyInformationAsync(DocumentServiceRequest request, Document document, Documents.Client.RequestOptions options)
        {
            CollectionCache collectionCache = await this.GetCollectionCacheAsync(NoOpTrace.Singleton);
            ContainerProperties collection = await collectionCache.ResolveCollectionAsync(request, CancellationToken.None, NoOpTrace.Singleton);
            PartitionKeyDefinition partitionKeyDefinition = collection.PartitionKey;

            PartitionKeyInternal partitionKey;
            if (options?.PartitionKey != null && options.PartitionKey.Equals(Documents.PartitionKey.None))
            {
                partitionKey = collection.GetNoneValue();
            }
            else if (options?.PartitionKey != null)
            {
                partitionKey = options.PartitionKey.InternalKey;
            }
            else
            {
                partitionKey = DocumentAnalyzer.ExtractPartitionKeyValue(document, partitionKeyDefinition);
            }

            request.Headers.Set(HttpConstants.HttpHeaders.PartitionKey, partitionKey.ToJsonString());
        }

        internal async Task AddPartitionKeyInformationAsync(DocumentServiceRequest request, Documents.Client.RequestOptions options)
        {
            CollectionCache collectionCache = await this.GetCollectionCacheAsync(NoOpTrace.Singleton);
            ContainerProperties collection = await collectionCache.ResolveCollectionAsync(request, CancellationToken.None, NoOpTrace.Singleton);
            PartitionKeyDefinition partitionKeyDefinition = collection.PartitionKey;

            // For backward compatibility, if collection doesn't have partition key defined, we assume all documents
            // have empty value for it and user doesn't need to specify it explicitly.
            PartitionKeyInternal partitionKey;
            if (options?.PartitionKey == null)
            {
                if (partitionKeyDefinition == null || partitionKeyDefinition.Paths.Count == 0)
                {
                    partitionKey = PartitionKeyInternal.Empty;
                }
                else
                {
                    throw new InvalidOperationException(RMResources.MissingPartitionKeyValue);
                }
            }
            else if (options.PartitionKey.Equals(Documents.PartitionKey.None))
            {
                partitionKey = collection.GetNoneValue();
            }
            else
            {
                partitionKey = options.PartitionKey.InternalKey;
            }

            request.Headers.Set(HttpConstants.HttpHeaders.PartitionKey, partitionKey.ToJsonString());
        }

        private JsonSerializerSettings GetSerializerSettingsForRequest(Documents.Client.RequestOptions requestOptions)
        {
            return requestOptions?.JsonSerializerSettings ?? this.serializerSettings;
        }

        private INameValueCollection GetRequestHeaders(
            Documents.Client.RequestOptions options,
            OperationType operationType,
            ResourceType resourceType)
        {
            Debug.Assert(
                this.isSuccessfullyInitialized,
                "GetRequestHeaders should be called after initialization task has been awaited to avoid blocking while accessing ConsistencyLevel property");

            RequestNameValueCollection headers = new RequestNameValueCollection();

            if (this.UseMultipleWriteLocations)
            {
                headers.Set(HttpConstants.HttpHeaders.AllowTentativeWrites, bool.TrueString);
            }

            if (this.desiredConsistencyLevel.HasValue)
            {
                // check anyways since default consistency level might have been refreshed.
                if (!this.IsValidConsistency(
                            backendConsistency: this.accountServiceConfiguration.DefaultConsistencyLevel, 
                            desiredConsistency: this.desiredConsistencyLevel.Value,
                            operationType: operationType,
                            resourceType: resourceType))
                {
                    throw new ArgumentException(string.Format(
                            CultureInfo.CurrentUICulture,
                            RMResources.InvalidConsistencyLevel,
                            options.ConsistencyLevel.Value.ToString(),
                            this.accountServiceConfiguration.DefaultConsistencyLevel));
                }

                headers.ConsistencyLevel = this.desiredConsistencyLevel.Value.ToString();
            }

            if (options == null)
            {
                return headers;
            }

            if (options.AccessCondition != null)
            {
                if (options.AccessCondition.Type == Documents.Client.AccessConditionType.IfMatch)
                {
                    headers.IfMatch = options.AccessCondition.Condition;
                }
                else
                {
                    headers.IfNoneMatch = options.AccessCondition.Condition;
                }
            }

            if (options.ConsistencyLevel.HasValue)
            {
                if (!this.IsValidConsistency(
                            backendConsistency: this.accountServiceConfiguration.DefaultConsistencyLevel,
                            desiredConsistency: options.ConsistencyLevel.Value,
                            operationType: operationType,
                            resourceType: resourceType))
                {
                    throw new ArgumentException(string.Format(
                            CultureInfo.CurrentUICulture,
                            RMResources.InvalidConsistencyLevel,
                            options.ConsistencyLevel.Value.ToString(),
                            this.accountServiceConfiguration.DefaultConsistencyLevel));
                }

                headers.Set(HttpConstants.HttpHeaders.ConsistencyLevel, options.ConsistencyLevel.ToString());
            }

            if (options.PriorityLevel.HasValue)
            {
                headers.Set(HttpConstants.HttpHeaders.PriorityLevel, options.PriorityLevel.ToString());
            }

            if (options.IndexingDirective.HasValue)
            {
                headers.Set(HttpConstants.HttpHeaders.IndexingDirective, options.IndexingDirective.ToString());
            }

            if (options.PostTriggerInclude != null && options.PostTriggerInclude.Count > 0)
            {
                string postTriggerInclude = string.Join(",", options.PostTriggerInclude.AsEnumerable());
                headers.Set(HttpConstants.HttpHeaders.PostTriggerInclude, postTriggerInclude);
            }

            if (options.PreTriggerInclude != null && options.PreTriggerInclude.Count > 0)
            {
                string preTriggerInclude = string.Join(",", options.PreTriggerInclude.AsEnumerable());
                headers.Set(HttpConstants.HttpHeaders.PreTriggerInclude, preTriggerInclude);
            }

            if (!string.IsNullOrEmpty(options.SessionToken))
            {
                headers[HttpConstants.HttpHeaders.SessionToken] = options.SessionToken;
            }

            if (options.ResourceTokenExpirySeconds.HasValue)
            {
                headers.Set(HttpConstants.HttpHeaders.ResourceTokenExpiry, options.ResourceTokenExpirySeconds.Value.ToString(CultureInfo.InvariantCulture));
            }

            if (options.OfferType != null)
            {
                headers.Set(HttpConstants.HttpHeaders.OfferType, options.OfferType);
            }

            if (options.OfferThroughput.HasValue)
            {
                headers.Set(HttpConstants.HttpHeaders.OfferThroughput, options.OfferThroughput.Value.ToString(CultureInfo.InvariantCulture));
            }

            if (options.OfferEnableRUPerMinuteThroughput)
            {
                headers.Set(HttpConstants.HttpHeaders.OfferIsRUPerMinuteThroughputEnabled, bool.TrueString);
            }

            if (options.InsertSystemPartitionKey)
            {
                headers.Set(HttpConstants.HttpHeaders.InsertSystemPartitionKey, bool.TrueString);
            }

            //if (options.OfferAutopilotTier.HasValue)
            //{
            //    headers.Set(HttpConstants.HttpHeaders.OfferAutopilotTier, options.OfferAutopilotTier.ToString());
            //}

            //if (options.OfferAutopilotAutoUpgrade.HasValue)
            //{
            //    headers.Set(HttpConstants.HttpHeaders.OfferAutopilotAutoUpgrade, options.OfferAutopilotAutoUpgrade.ToString());
            //}

            if (options.EnableScriptLogging)
            {
                headers.Set(HttpConstants.HttpHeaders.EnableLogging, bool.TrueString);
            }

            if (options.PopulateQuotaInfo)
            {
                headers.Set(HttpConstants.HttpHeaders.PopulateQuotaInfo, bool.TrueString);
            }

            if (options.PopulateRestoreStatus)
            {
                headers.Set(HttpConstants.HttpHeaders.PopulateRestoreStatus, bool.TrueString);
            }

            if (options.PopulatePartitionKeyRangeStatistics)
            {
                headers.Set(HttpConstants.HttpHeaders.PopulatePartitionStatistics, bool.TrueString);
            }

            if (options.DisableRUPerMinuteUsage)
            {
                headers.Set(HttpConstants.HttpHeaders.DisableRUPerMinuteUsage, bool.TrueString);
            }

            if (options.RemoteStorageType.HasValue)
            {
                headers.Set(WFConstants.BackendHeaders.RemoteStorageType, options.RemoteStorageType.ToString());
            }

            if (options.PartitionKeyRangeId != null)
            {
                headers.Set(WFConstants.BackendHeaders.PartitionKeyRangeId, options.PartitionKeyRangeId);
            }

            if (options.SourceDatabaseId != null)
            {
                headers.Set(HttpConstants.HttpHeaders.SourceDatabaseId, options.SourceDatabaseId);
            }

            if (options.SourceCollectionId != null)
            {
                headers.Set(HttpConstants.HttpHeaders.SourceCollectionId, options.SourceCollectionId);
            }

            if (options.RestorePointInTime.HasValue)
            {
                headers.Set(HttpConstants.HttpHeaders.RestorePointInTime, options.RestorePointInTime.Value.ToString(CultureInfo.InvariantCulture));
            }

            if (options.IsReadOnlyScript)
            {
                headers.Set(HttpConstants.HttpHeaders.IsReadOnlyScript, bool.TrueString);
            }

            if (options.IncludeSnapshotDirectories)
            {
                headers.Set(HttpConstants.HttpHeaders.IncludeSnapshotDirectories, bool.TrueString);
            }

            if (options.ExcludeSystemProperties.HasValue)
            {
                headers.Set(WFConstants.BackendHeaders.ExcludeSystemProperties, options.ExcludeSystemProperties.Value.ToString());
            }

            if (options.MergeStaticId != null)
            {
                headers.Set(HttpConstants.HttpHeaders.MergeStaticId, options.MergeStaticId);
            }

            if (options.PreserveFullContent)
            {
                headers.Set(HttpConstants.HttpHeaders.PreserveFullContent, bool.TrueString);
            }
            return headers;
        }

        private class ResetSessionTokenRetryPolicyFactory : IRetryPolicyFactory
        {
            private readonly IRetryPolicyFactory retryPolicy;
            private readonly ISessionContainer sessionContainer;
            private readonly ClientCollectionCache collectionCache;

            public ResetSessionTokenRetryPolicyFactory(ISessionContainer sessionContainer, ClientCollectionCache collectionCache, IRetryPolicyFactory retryPolicy)
            {
                this.retryPolicy = retryPolicy;
                this.sessionContainer = sessionContainer;
                this.collectionCache = collectionCache;
            }

            public IDocumentClientRetryPolicy GetRequestPolicy()
            {
                return new RenameCollectionAwareClientRetryPolicy(this.sessionContainer, this.collectionCache, this.retryPolicy.GetRequestPolicy());
            }
        }

        private class HttpRequestMessageHandler : DelegatingHandler
        {
            private readonly EventHandler<SendingRequestEventArgs> sendingRequest;
            private readonly EventHandler<ReceivedResponseEventArgs> receivedResponse;

            public HttpRequestMessageHandler(EventHandler<SendingRequestEventArgs> sendingRequest, EventHandler<ReceivedResponseEventArgs> receivedResponse, HttpMessageHandler innerHandler)
            {
                this.sendingRequest = sendingRequest;
                this.receivedResponse = receivedResponse;

                this.InnerHandler = innerHandler ?? new HttpClientHandler();
            }

            protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
            {
                this.sendingRequest?.Invoke(this, new SendingRequestEventArgs(request));
                HttpResponseMessage response = await base.SendAsync(request, cancellationToken);
                this.receivedResponse?.Invoke(this, new ReceivedResponseEventArgs(request, response));
                return response;
            }
        }

        #endregion
    }
}