Is it intended that if a Subscription does not exist a ServiceBusCommunicationEx is thrown instead of a MessagingEntityNotFoundEx?

[TheReaLee]

Query/Question
Is it intended that if a Subscription does not exist a ServiceBusCommunicationEx is thrown rather than a MessagingEntityNotFoundException?

Why is this not a Bug or a feature Request?
Our team is currently building a wrapper around the Microsoft.Azure.ServiceBus project and have noticed that when a Topic or Queue does not exist a MessagingEntityNotFoundException is thrown whereas when a Subscription does not exists a ServiceBusCommunicationException is thrown.

Is this intended and if yes why so?... Doesn't a Topic + Subscription make up a Messaging Entity?

Setup

• OS: Windows 10 version 1809
• IDE : Visual Studio Enterprise 2019
• Version of the Library used: 3.4.0

protected override void SubscribeInternal()
{
	RetryExponential retryExponential = new RetryExponential(TimeSpan.FromSeconds(5), TimeSpan.FromSeconds(20), 3);

	string topicName = "TestTopic";
	//This subscription has not been created
	string subscriptionName = "Sub1";

        _azureSubscriptionClient = new SubscriptionClient(this._getConnectionString(), topicName, subscriptionName, ReceiveMode.PeekLock, retryExponential);
	MessageHandlerOptions messageHandlerOptions = new MessageHandlerOptions(_onExceptionThrownHandler)
	{                   
	    MaxConcurrentCalls = _topicSubscriptionConnectionOptions.MaxConcurrentMessages,                   
	    AutoComplete = false
	};
	_azureSubscriptionClient.RegisterMessageHandler(_onMessageReceivedHandler, messageHandlerOptions);
}

private Task _onExceptionThrownHandler(ExceptionReceivedEventArgs exceptionReceivedEventArgs)
{
    Exception exception = exceptionReceivedEventArgs.Exception;
    //exception.GetType() == 'ServiceBusCommunicationException'
    ...
}

private async Task _onMessageReceivedHandler(Message message, CancellationToken token)
{
    ...
}

[kurtzeborn]

Thanks for opening this issue. I've attempted to route this to the appropriate team who should be able to get you an answer on what's going on here.

[TheReaLee]

@kurtzeborn any news about this?

[jsquire]

@nemakam, @binzywu : Would one of you be so kind as to offer your thoughts?

[SeanFeldman]

I think the issue is more general. It's not just about subscriptions. It's about any entity. Currently, MessagingEntityNotFoundException is only thrown on NamespaceManager operations, but not MessageSender/MessageReceiver. I can send a PR.

[SeanFeldman]

I've run through a scenario where a connection is established, the subscription is removed, and an operation to send/receive a message is attempted. The issue is that AmqpLinkCreator.CreateAndOpenAmqpLinkAsync() will throw. When it does, it will convert the exception using AmqpExceptionHelper.GetClientException(connectionError), where connectionError is a boolean determined by session.IsClosing(). This will always be true given that a line above session.SafeClose(exception); is called. As a result of that AmqpExceptionHelper.ToMessagingContractException() will return ServiceBusCommunicationException rather than MessagingEntityNotFoundException.

Also, AmqpExceptionHelper.GetClientException() should handle a case with MessagingEntityNotFoundException and return aggregateException as-is.

@nemakam does this sound right to you?

[SeanFeldman]

BTW, a simpler way to repro this would be:

var receiver = new MessageReceiver(connectionString, "topic/sub"); // let `topic` exist, but not `sub`
await receiver.ReceiveAsync();

[axisc]

@TheReaLee - thanks for raising this.

I think this is definitely a MessagingEntityNotFoundException.
Adding it to the backlog and assigning the January milestone to it.

[ghost]

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