Real-time Web Applications with WebSockets

Real-time features transform static applications into dynamic, engaging experiences. Here's how to implement them effectively.

WebSockets vs Polling

WebSockets maintain a persistent connection, making them ideal for:
- Live chat
- Real-time notifications
- Collaborative editing
- Live dashboards

## Getting Started with Socket.io

``typescript
// Server
import { createServer } from 'http';
import { Server } from 'socket.io';

const httpServer = createServer(app);
const io = new Server(httpServer, {
cors: { origin: process.env.CLIENT_URL }
});

io.on('connection', (socket) => {
socket.on('message', (data) => {
io.to(data.room).emit('message', data);
});
});
`

## Scaling WebSocket Servers

Use Redis adapter for horizontal scaling:

`typescript
import { createAdapter } from '@socket.io/redis-adapter';
io.adapter(createAdapter(pubClient, subClient));
``

## Best Practices

- Authenticate socket connections
- Use rooms for namespace isolation
- Implement reconnection logic
- Handle disconnections gracefully