Real-time chat application dengan WebSocket, typing indicators, read receipts, file sharing, dan message persistence menggunakan Redis.

Real-time Chat Application

A feature-rich real-time messaging platform built with WebSocket technology for instant communication.

Features

Core Messaging

• Instant Messaging: Real-time message delivery with WebSocket
• Typing Indicators: See when other users are typing
• Read Receipts: Know when messages are delivered and read
• Online Status: Real-time user presence indicators
• Message History: Persistent chat history with Redis

Advanced Features

• File Sharing: Upload and share images, documents, and files
• Group Chats: Create and manage group conversations
• Message Search: Full-text search across all conversations
• Emoji Support: Rich emoji picker integration
• Message Reactions: React to messages with emojis

Technical Implementation

WebSocket Architecture

Using Socket.io for bidirectional communication:

// Server-side event handling
io.on('connection', (socket) => {
  socket.on('message', async (data) => {
    await saveMessage(data);
    socket.broadcast.emit('new-message', data);
  });

  socket.on('typing', (room) => {
    socket.to(room).emit('user-typing', socket.id);
  });
});

Backend (NestJS)

• WebSocket Gateway for Socket.io integration
• Redis adapter for horizontal scaling
• Message Queue for reliable delivery
• File upload with AWS S3 integration
• Authentication with JWT tokens

Frontend (React)

• Custom hooks for WebSocket management
• Optimistic updates for immediate UI feedback
• Infinite scroll for message history
• Progressive image loading for file attachments
• Audio notifications for new messages

Performance Optimizations

Scalability

• Redis Pub/Sub: Enable multiple server instances
• Message pagination: Load messages on demand
• Connection pooling: Efficient database connections
• CDN integration: Fast file delivery

Real-time Performance

• WebSocket heartbeat: Maintain connection health
• Automatic reconnection: Handle network interruptions
• Message batching: Reduce API calls
• Client-side caching: Store recent messages locally

Challenges Overcome

Challenge: Handling thousands of concurrent connections.

Solution: Implemented Redis adapter for Socket.io to distribute connections across multiple server instances.

Challenge: Message ordering in distributed system.

Solution: Used Redis sorted sets with timestamps to maintain consistent message order across all clients.

Metrics

• Supports 1000+ concurrent users
• Message delivery latency: < 50ms
• File upload speed: Up to 10MB/s
• 99.95% uptime over 3 months