• Instructions on how to compile your service

Need java 8 and latest maven installed 
clone the git repo
get into the project directory -> cd chat
compile using the following command 
mvn clean install

• Instructions on how to run your service locally

java  -jar target/chat-0.0.1-SNAPSHOT.jar com.ua.chat.ChatApplication

• The decisions you made

Used H2 inmemory database
Tried to deliver the features as per given spec
Integrated with Swagger to see the rest documentation
To see the swagger documentaion, use the below URL : 
  http://localhost:8080/swagger-ui.html
Written test cases for rest layer and persistency layer 
Since apis specs are expecting different type of response, i have created multiple models and resources 
Tested the service for 1 minute with 100 users and throughput is around 800 per second

• The limitations of your implementation

It has in-memory database - H2
Not integrated with relational database
No cache implementation
Limited test cases
No index on username column

• What you would do if you had more time

Good documentation of classes/interfaces
Better exception handling with error codes and custom exceptions
I would have written more unit test cases and integration test cases using karate framework 

• How you would scale it in the future

scaling application perspectinve, 
  a) need to use non blocking io /reactive programming and that makes application more scalable
  b) not using any state makes ie easier to scale horizontally       
scaling database perspectinve, data access layer need changes 

api examples:

• POST /chat

POST /chat HTTP/1.1
Host: localhost:8080
Content-Type: application/json
cache-control: no-cache
Postman-Token: f6a45fad-916b-4b38-a726-63b2c994d5b7
{    	
"username": "paulrad", "text": "This is a messagwe2ww23", "timeout": 30
}

• GET /chat/:id

GET /chat/2 HTTP/1.1
Host: localhost:8080
Content-Type: application/json
cache-control: no-cache
Postman-Token: 7fee5cf1-ca69-4756-ae05-151630ea99d9
{    	
"username": "paulrad", "text": "This is a messagwe2ww23", "timeout": 30
}    

• GET /chats/:username

GET /chats/paulrad HTTP/1.1
Host: localhost:8080
Content-Type: application/json
cache-control: no-cache
Postman-Token: edee118a-06b4-4b77-88e5-b196d2f97685
{    	
"username": "paulrad", "text": "This is a messagwe2ww23", "timeout": 30
}