StateStringService

Required :

• Maven
• Java 8

Tools/Libraries and DB Used:

• DB : DynamoDB
• REST API doc : Swagger
• Unit Tests: Junit, Mockito
• Logging : Simple Logging Facade for Java (SLF4J)

Assumptions and considerations :

• Since cookies were not allowed to use I have used UUID generator of java library to generate userId
• I have used Dynamo DB since the application can be easily deployed in AWS cloud
• Right now the configurations in the application.properties are pointing to local but can be made production ready jusy by updating the url and keys
• Regarding : POST /chars - adds the character/s to the string state, e.g. with JSON input {“character”:”a”,”amount”:3} adds “aaa” to the state string : I assumed that the characters are added at end

Endpoint for Testing:

Have added an end point /addState just for adding a state String for testing purpose

PreRequisites :

Download the Dynamodb JAR for setting up the DB in local from the link : http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/DynamoDBLocal.html

Extract the Jar and run the command : java -Djava.library.path=./DynamoDBLocal_lib -jar DynamoDBLocal.jar sharedDb

Once the DynamoDB started goto http://localhost:8000/shell and Create a table named User :

var params = {
  AttributeDefinitions: [
     {
    AttributeName: "userId", 
    AttributeType: "S"
   }, 
     {
    AttributeName: "stateString", 
    AttributeType: "S"
   }
  ], 
  KeySchema: [
     {
    AttributeName: "userId", 
    KeyType: "HASH"
   }
  ], 
  GlobalSecondaryIndexes: [{
                IndexName: "FactoryIndex",
                KeySchema: [
                    {
                        AttributeName: "userId",
                        KeyType: "HASH"
                    },
                    {
                        AttributeName: "stateString",
                        KeyType: "RANGE"
                    }
                ],
                Projection: {
                    ProjectionType: "ALL"
                },
                ProvisionedThroughput: {
                    ReadCapacityUnits: 1,
                    WriteCapacityUnits: 1
                }
            }],
  ProvisionedThroughput: {
   ReadCapacityUnits: 5, 
   WriteCapacityUnits: 5
  }, 
  TableName: "User"
 };
 dynamodb.createTable(params, function(err, data) {
   if (err) console.log(err, err.stack); // an error occurred
   else     console.log(data);           // successful response
   
 });

Start Application:

Once Dynamo DB is running in local and table is created go to the root directory . Run the command

mvn spring-boot:run

You can see the end points in Swagger with Docs: http://localhost:8080/swagger-ui.html

Run UnitTests:

Go to the root directory . Run the command

mvn verify

Requirements Completion Status:

Created Java & Spring Boot, RESTful, JSON-based web service that keeps a String state per person (per browser). The initial state for new user is empty String ""

requirements:

• do not use cookies - Done
• each operation logs what it is doing in a log/console, e.g. userID: “ab85c56a”, added: “a”, 2 times - Logged trace, info, error statements
• two different browsers from single computer are two different users - Since cookies could not be used I used UUID which will change with the browser since the scope of the controller is "session" and user from same machine and different browser will be treated as different clients and tabs in same browser as same client
• provide an instruction how to install your solution (including dependencies) and start it (on linux or mac) - provided above

supported operations: All Done

• GET /state - returns the current state - Done
• GET /sum - sums all numbers in a string, e.g. “5abc141def” returns 146, if there are no numbers return 0 - Done
• GET /chars - shows the current state without numbers, e.g. “5abc141def” returns abcdef - Done
• POST /chars - adds the character/s to the string state, e.g. with JSON input {“character”:”a”,”amount”:3} adds “aaa” to the state string - Done
• DELETE /chars/ - deletes the last occurrence of the character in the state string - Done

web services requirements: All Done

• return 400 if the POST request contains invalid JSON
• character in DELETE has to be a single alphanumeric character, otherwise return 400
• character in POST request has to be just one alphanumeric character and amount a number from 1 to 9, otherwise return 400
• if the length of the string state will exceed 200 characters after the POST request, do not change the state and return 400
• wrong url returns 404
• each valid JSON response (200 class) includes a user hash/id

bonus points: All done

• put your solution on GitHub (personal account)
• write unit tests
• use database to store the state