WebSocket Server for Submission Processing

This WebSocket server is a real-time communication backend designed to handle student submission results. It integrates with Redis to manage connections and uses Pub/Sub for processing updates from the Result Worker. This architecture supports scalability by allowing multiple WebSocket servers to work in parallel, all subscribing to the same Pub/Sub channels.

Features

• Pub/Sub Integration: Listens to positive-processed and negative-processed channels for real-time updates.
• WebSocket Connection Management: Stores and retrieves client connections using Redis, mapped to their respective student IDs.
• Scalable Architecture: Multiple WebSocket servers can subscribe to the same Pub/Sub channels for horizontal scaling.
• Real-Time Notifications:
  • Sends a positive message to students with verified submissions.
  • Sends a negative message to students with failed verification, triggering their system to shut down.

How It Works

1. Connection Management:

   • When a client connects, their WebSocket remoteAddress is stored in Redis, mapped to their student ID.
   • If a client disconnects, the mapping is removed.

2. Message Handling:

   • On receiving a message from the positive-processed channel, the server sends a positive signal to the relevant client.
   • On receiving a message from the negative-processed channel, the server sends a negative signal to the relevant client, shutting down the student's system and notifying authorities.

3. Scalability:

   • Multiple WebSocket servers can be deployed, all subscribing to the same Pub/Sub channels for distributed processing.

Prerequisites

1. Node.js (version >= 16)
2. Redis (for Pub/Sub and connection management)
3. Docker (optional, for running Redis in a container)
4. Git

Installation

Follow these steps to set up the WebSocket server in your environment:

1. Clone the repository:

   git clone https://github.com/priyanshubisht10/websocket-server.git
   cd websocket-server

2. Install dependencies:

    npm install

3. Make sure your redis-stack is up and running and the worker is able to publish to the pub/sub. If you haven't installed the worker it yet, you can find the steps here - (https://github.com/priyanshubisht10/result-worker)
4. Build

    tsc -b

5. Start the server:

   node dist/app.js

6. Verify the setup: If everything is set up correctly, you should see the following log in the terminal:

   Server is listening on port 3000

Additional Resources

For a detailed explanation of the architecture, functionality, and use cases of this WebSocket server, check out this Medium article by me:
https://priyanshubisht10.medium.com/pub-sub-and-websockets-d8d180c2b9e8