Messenger Demo

This demo application is a simple messaging service. Users can post and retrieve messages using the REST API.

Prerequisites

• Docker

Running the application locally

There are two options running the demo application locally, the first one uses docker-compose, the latter docker swarm.

• Using Docker Compose

  $ docker-compose -f src/main/docker/docker-compose-separate-servers.yml up
  

  This command will expose 2 services on your system:

  • Spring Boot (instance 1) application on 127.0.0.1:8080
  • Spring Boot (instance 2) application on 127.0.0.1:8081

  If you open two separate browsers with 127.0.0.1:8080 and 127.0.0.1:8081 you should be able to see the message boards. After you POST new messages to the correct resource, messages should appear in both browsers.

• Using Docker Swarm

  1. Make sure to enable swarm mode

     $ docker swarm init
     

  2. Start the services

     $ docker stack deploy -c src/main/docker/docker-compose.yml messenger-demo
     

  After running these commands you should be able access the application on 127.0.0.1:8080. Please note that by default there are two replicas of the backend and reverse-proxy is applied by docker swarm.

REST API

Retrieve all messages

URL: /messages

Method: GET

Success response

Code: 200 (OK)

Example response

[
  {
    "id":1,
    "content":"Hello"
  },
  {
    "id":2,
    "content":"Hi"
  }
]

Add new message

URL: /messages

Method: POST

Required parameters

• content
  • Content of the message
  • Type: String

Example data format

{
  "content": "Hello"
}

Success response

Code: 201 (Created)

Example response

{
  "id":1,
  "content":"Hello"
}

Error response

Code: 400 (Bad Request)

Cause: Data is not in a valid format

Getting started with developing the application

1. Start Postgres:

   $ docker run --name messenger-demo-postgres -p 5432:5432 -e POSTGRES_USER=messenger -e POSTGRES_PASSWORD=messenger -d postgres
   

   Change the parameters according to your system needs. This will expose the default Postgres port (5432).

2. Start RabbitMQ:

   $ docker run -d -p 5672:5672 -p 15672:15672 --name messenger-demo-rabbit rabbitmq:3
   

Running the application with Gradle:

$ ./gradlew bootRun

Pushing changes to Docker Hub:

$ ./gradlew build dockerPush

Running tests

$ ./gradlew test

Running integration tests

Make sure that there is a RabbitMQ instance running then:

$ ./gradlew testInteg

Requirements

The task is to implement a data processing pipeline in the cloud.

• Set up a running environment aligned with the technologies mentioned below
• A Readme file containing information you deem useful for someone getting to know your code and want to try the system out
• Develop the application in Java 8, using either DropWizard or Spring Boot as the foundation
• A REST endpoint is taking a dummy JSON input, and the server puts the REST payload on Redis or another tool you think is well suited for the task
• A Consumer is running in the application, taking the freshly received message and persists it in a database of your choice
• A REST endpoint is implemented for retrieving all the messages persisted in JSON format from the database
• The message should also be pushed through Websockets for listening browser clients at the time the message was received on the REST endpoint
• A simple HTML page is implemented to show the real time message delivery
• Please setup a github repository to host the code and share it with your final note for review

We're looking for that:

• All tasks are solved in the solution
• The application has a solid commit history
• The application is built with scalability and maintainability in mind
• The application is built for testability, demonstrated by actual tests
• Your solution reflects a sense of quality you would be confident in releasing to production
• Documentation is applied to code / repository describing intent and purpose, as well as complicated / non obvious choices in the implementation