WebSocket Chat

A real-time multi-room chat application built with Go, demonstrating WebSocket architecture, Go concurrency patterns, and distributed messaging with Redis.

Features

• Real-time messaging via WebSockets
• Multi-room support
• JWT-based authentication (stateless, no database)
• Redis Pub/Sub for horizontal scaling
• Room-owned concurrency model (actor pattern)
• Buffered channels with backpressure handling

Architecture

┌─────────────┐     ┌─────────────┐
│  Browser 1  │     │  Browser 2  │
└──────┬──────┘     └──────┬──────┘
       │ WebSocket         │ WebSocket
       ▼                   ▼
┌─────────────────────────────────┐
│           Go Server             │
│  ┌─────────┐    ┌─────────┐    │
│  │ Room 0  │    │ Room 1  │    │
│  │(goroutine)   │(goroutine)   │
│  └────┬────┘    └────┬────┘    │
└───────┼──────────────┼─────────┘
        │              │
        ▼              ▼
┌─────────────────────────────────┐
│         Redis Pub/Sub           │
│   (enables multiple servers)    │
└─────────────────────────────────┘

Quick Start

Prerequisites

• Go 1.21+
• Docker (for Redis)

Run

# Start Redis
docker run -d --name redis -p 6379:6379 redis

# Copy env file
cp .env.example .env

# Run server
go run cmd/server/main.go

Open http://localhost:8080 in your browser.

Project Structure

├── cmd/server/          # Application entrypoint
├── internal/
│   ├── auth/            # JWT authentication
│   ├── config/          # Configuration & logging
│   ├── pubsub/          # Redis Pub/Sub client
│   └── websocket/       # WebSocket handling
│       ├── client.go    # Per-connection handler
│       ├── manager.go   # Connection management
│       ├── room.go      # Room actor (goroutine per room)
│       └── event.go     # Message types
└── frontend/            # Simple HTML/CSS/JS UI

Key Concepts

Room-Owned Concurrency

Each room runs as an independent goroutine (actor model):

• Owns its client list
• Handles join/leave via channels
• Receives messages from Redis subscription

Redis Pub/Sub

Enables horizontal scaling:

• Messages published to room:{name} channel
• All server instances subscribe and fan out to local clients

JWT Authentication

Stateless guest authentication:

• No user database needed
• Username stored in JWT claims
• Token validated on WebSocket connection

Configuration

Variable	Default	Description
PORT	8080	Server port
LOG_LEVEL	info	debug, info, warn, error
REDIS_ADDR	localhost:6379	Redis address

License

MIT