WebSocket Echo Application

A secure WebSocket server and client implementation in Node.js that demonstrates real-time bidirectional communication. The application includes features like automatic reconnection, proper error handling, and connection management.

Features

• Secure WebSocket Server

  • Origin validation for connection security
  • Connection limit management to prevent DoS attacks
  • Proper error handling and logging
  • Support for both UTF-8 and binary messages
  • Automatic ping/pong for connection health monitoring

• Robust WebSocket Client

  • Automatic reconnection on connection loss
  • Graceful error handling
  • Resource cleanup on disconnection
  • Configurable message intervals

Prerequisites

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

Installation

1. Clone the repository
2. Install dependencies:

   pnpm install

Configuration

The application can be configured using environment variables. Create a .env file in the root directory with the following options:

Server Configuration

PORT=8080
ALLOWED_ORIGINS=http://localhost:3000,ws://localhost:8080
MAX_CONNECTIONS=100

Client Configuration

WS_URL=ws://localhost:8080/
RECONNECT_INTERVAL=5000
MESSAGE_INTERVAL=1000

Usage

1. Start the WebSocket server:

   pnpm start
   # or for development mode with auto-reload:
   pnpm run dev

2. In another terminal, start the client:

   pnpm run start:client
   # or for development mode with auto-reload:
   pnpm run dev:client

How It Works

1. The server listens for WebSocket connections on the configured port
2. When a client connects, the server validates the connection origin
3. Upon successful connection:
   • The client starts sending random numbers to the server every second
   • The server echoes back each received message
   • The server maintains a ping/pong mechanism to keep connections alive
   • If the connection drops, the client automatically attempts to reconnect

Error Handling

The application implements comprehensive error handling:

• Connection validation errors
• Message processing errors
• Connection cleanup errors
• Automatic reconnection on failures
• Resource cleanup on termination

Development

The project uses nodemon for development, which automatically restarts the application when files change. Use the dev scripts for development:

pnpm run dev        # For server
pnpm run dev:client # For client

License

ISC License