instagram-backend

Architecture

HTTP Server

A Netty server accepts HTTP requests on port 8080. This server receives an HTTP POST request, parses its JSON payload, makes sure the user is authenticated, uploads media file(s) (if any) to a media server & injects the returned URL(s) into the JSON payload, stamps the payload with a UUID & forwards it to a RabbitMQ queue using the requests_mapping.properties file, then it waits for a response with the same UUID and returns to the user when it gets a response with a matching UUID.

Services

Each service consists of an RMQ consumer, RMQ producer & an ExecutorService. Each service also has its own unique request & response queue.

• RMQ Consumer: Receives messages from the service's request queue
• RMQ Producer: Sends messages to the service's response queue
• ExecutorService: Initializes a thread pool & makes sure every incoming message gets allocated a thread from the thread pool

Prerequisites

• Java (8 or higher)
• Docker
• Postman (for testing)

Getting started

• Clone the repo & open in IntelliJ
• Change directory to repository folder cd <path/to/repo>
• Run docker-compose up
• Open Maven Projects tab, expand Lifecycle & click compile
• Open Maven Projects tab, expand Plugins, expand activejdbc-instrumentation & click activejdbc-instrumentation:instrument
• Navigate to persistence package, expand sql/users, click & run Migrations.java. This file creates the SQL tables.
• Navigate to persistence package, expand nosql, click & run ArangoInterfaceMethods.java. This file creates the NoSQL tables & graphs.

Running the app

• Run src/main/java/http_server/Server.java, this makes sure that the server is running on port 8080 & ready to accept HTTP requests
• Run src/main/java/services/users/Server.java, this file initializes an RMQ consumer for the users service that will be later used to authenticate requests
• Run src/main/java/services/activities/Server.java, this file initializes an RMQ consumer for activities that will be later used by other services
• Run src/main/java/services/<your-service>/Server.java, this also initializes an RMQ consumer for the specified service

Sending requests

• Open Postman
• In the URL field, write http://localhost:8080/
• Choose the type of the request to be POST request
• Underneath the URL field, click on Body, choose raw from the presented options
• Send a Sign up or Sign in request to obtain a token that will be used for authenticating other requests

{
  "method" : "signup",
  "params": {
      "username" : "john_doe",
      "email" : "john.doe@user.com",
      "password" : "123456",
      "isPrivate": false,
      "fullName" : "John Doe",
      "gender" : "male"
  }
}

• Using the returned token, go ahead and create a new tab in Postman, choose the same options mentioned eariler. Before sending the request, go to Headers tab and add x-access-token with the obtained token (obviously, we don't add any headers in the case of sending signup or login requests)