WebSocket Chat Application - Node.js Backend

This is a Node.js implementation of the WebSocket chat application, providing the same functionality as the Go version.

Features

• User authentication with OTP-based login
• Real-time WebSocket communication
• Multiple chat rooms support
• Ping-pong heartbeat mechanism
• Auto-cleanup of expired OTPs
• CORS support for cross-origin requests

Prerequisites

• Node.js (v14 or higher)
• npm or yarn

Installation

1. Navigate to the nodejs-backend directory:

   cd nodejs-backend

2. Install dependencies:

   npm install

Running the Server

Development mode (with auto-restart):

npm run dev

Production mode:

npm start

The server will start on port 8080 by default. You can access the application at http://localhost:8080.

API Endpoints

POST /login

Authenticate user and receive OTP for WebSocket connection.

Request body:

{
  "username": "balu",
  "password": "123"
}

Response:

{
  "otp": "generated-uuid-string"
}

WebSocket Connection

Connect to WebSocket at ws://localhost:8080/ws?otp=YOUR_OTP&name=USERNAME

Valid Users

The following users are pre-configured with password "123":

• balu
• yaswanth
• person1
• person2

WebSocket Events

Send Message

{
  "type": "send_message",
  "payload": {
    "message": "Hello, World!",
    "from": "username"
  }
}

Change Chat Room

{
  "type": "change_chatroom",
  "payload": {
    "name": "room-name"
  }
}

New Message (Broadcast)

{
  "type": "new_message",
  "payload": {
    "message": "Hello, World!",
    "from": "username",
    "sent": "2023-12-07T10:30:00.000Z"
  }
}

File Structure

• server.js - Main server file with Express and WebSocket setup
• manager.js - WebSocket connection manager and event routing
• client.js - Individual client connection handling
• otp.js - OTP generation and verification system
• events.js - Event type constants
• package.json - Project dependencies and scripts

Security Features

• OTP-based authentication
• One-time use OTPs with automatic expiration (5 seconds)
• Connection verification before WebSocket upgrade
• Automatic cleanup of expired OTPs

Differences from Go Version

• Uses HTTP instead of HTTPS (can be easily modified for HTTPS)
• Uses ws library instead of Gorilla WebSocket
• Express.js for HTTP server instead of Go's net/http
• UUID v4 for OTP generation instead of Google UUID