/real-time-features

name: real-time-features
description: >
  Implement real-time functionality using WebSockets, Server-Sent Events (SSE),
  or long polling. Use when building chat applications, live dashboards,
  collaborative editing, notifications, or any feature requiring instant
  updates.

Real-Time Features

Table of Contents

• [Overview](#overview)
• [When to Use](#when-to-use)
• [Quick Start](#quick-start)
• [Reference Guides](#reference-guides)
• [Best Practices](#best-practices)

Overview

Implement real-time bidirectional communication between clients and servers for instant data synchronization and live updates.

When to Use

• Chat and messaging applications
• Live dashboards and analytics
• Collaborative editing (Google Docs-style)
• Real-time notifications
• Live sports scores or stock tickers
• Multiplayer games
• Live auctions or bidding systems
• IoT device monitoring
• Real-time location tracking

Quick Start

Minimal working example:

// server.ts
import WebSocket, { WebSocketServer } from "ws";
import { createServer } from "http";

interface Message {
  type: "join" | "message" | "leave" | "typing";
  userId: string;
  username: string;
  content?: string;
  timestamp: number;
}

interface Client {
  ws: WebSocket;
  userId: string;
  username: string;
  roomId: string;
}

class ChatServer {
  private wss: WebSocketServer;
  private clients: Map<string, Client> = new Map();
  private rooms: Map<string, Set<string>> = new Map();

  constructor(port: number) {
// ... (see reference guides for full implementation)

Reference Guides

Detailed implementations in the `references/` directory:

| Guide | Contents | |---|---| | [WebSocket Server (Node.js)](references/websocket-server-nodejs.md) | WebSocket Server (Node.js) | | [WebSocket Client (React)](references/websocket-client-react.md) | WebSocket Client (React) | | [Server-Sent Events (SSE)](references/server-sent-events-sse.md) | Server-Sent Events (SSE) | | [Socket.IO (Production-Ready)](references/socketio-production-ready.md) | Socket.IO (Production-Ready) |

Best Practices

✅ DO

• Implement reconnection logic with exponential backoff
• Use heartbeat/ping-pong to detect dead connections
• Validate and sanitize all messages
• Implement authentication and authorization
• Handle connection limits and rate limiting
• Use compression for large payloads
• Implement proper error handling
• Monitor connection health
• Use rooms/channels for targeted messaging
• Implement graceful shutdown

❌ DON'T

• Send sensitive data without encryption
• Keep connections open indefinitely without cleanup
• Broadcast to all users when targeted messaging suffices
• Ignore connection state management
• Send large payloads frequently
• Skip message validation
• Forget about mobile/unstable connections
• Ignore scaling considerations