Live Chat Application

A real-time chat application with two different implementations: WebSocket and Long Polling.

Overview

This repository contains two approaches to building real-time chat applications:

• WebSocket - Bidirectional persistent connection for instant messaging
• Long Polling - HTTP-based polling mechanism for message updates

Both implementations demonstrate different techniques for achieving real-time communication.

Project Structure

Live-Chat/
├── WebSocket/        # WebSocket-based chat with authentication
│   ├── backend/      # Express.js + WebSocket server
│   ├── frontend/     # Vite + Vanilla JS client
│   └── README.md
└── LongPolling/      # Long polling-based chat
    ├── backend/      # Express.js server
    ├── frontend/     # Vanilla JS client
    └── README.md

WebSocket Implementation

A full-featured chat application with user authentication, message reactions, and persistent database.

Features:

• User registration and login with JWT
• Real-time messaging via WebSocket
• Message reactions (like/dislike)
• SQLite database with Knex
• Secure HTTP-only cookies
• Comprehensive error handling

Tech: Express.js, WebSocket (ws), SQLite3, Knex.js, JWT, Bcrypt

Quick Start:

cd WebSocket/backend
npm install
node migrations/init.js
node app.js

# In another terminal
cd WebSocket/frontend
npm install
npm run dev

Open http://localhost:5173

Long Polling Implementation

A lightweight chat application using HTTP long polling for message retrieval.

Features:

• Simple user messaging
• No authentication required
• In-memory message storage
• Minimal dependencies
• Long polling mechanism with 25-second timeout

Tech: Express.js, Vanilla JavaScript

Quick Start:

cd LongPolling/backend
npm install
npm start

# Open LongPolling/frontend/index.html in browser

Comparison

Feature	WebSocket	Long Polling
Connection Type	Persistent	HTTP polling
Latency	Instant	100ms polling
Scalability	Requires connection management	Simpler to scale
Complexity	Higher	Lower
Database	SQLite	In-memory
Authentication	JWT + Bcrypt	None
Reactions	Yes	No

Getting Started

Choose one implementation and follow the Quick Start guide above, or check individual README files in each directory for detailed documentation.

Tech Stack

Common:

• Node.js
• Express.js

WebSocket:

• WebSocket (ws)
• SQLite3
• JWT
• Bcrypt

Long Polling:

• CORS

License

MIT