streaming-api-patterns

# Streaming API Patterns

## Overview

**When to use this skill:**
- Streaming LLM responses (ChatGPT-style interfaces)
- Real-time notifications and updates
- Live data feeds (stock prices, analytics)
- Chat applications
- Progress updates for long-running tasks
- Collaborative editing features

## Core Technologies

### 1. Server-Sent Events (SSE)

**Best for**: Server-to-client streaming (LLM responses, notifications)

```typescript
// Next.js Route Handler
export async function GET(req: Request) {
  const encoder = new TextEncoder()

  const stream = new ReadableStream({
    async start(controller) {
      // Send data
      controller.enqueue(encoder.encode('data: Hello\n\n'))

      // Keep connection alive
      const interval = setInterval(() => {
        controller.enqueue(encoder.encode(': keepalive\n\n'))
      }, 30000)

      // Cleanup
      req.signal.addEventListener('abort', () => {
        clearInterval(interval)
        controller.close()
      })
    }
  })

  return new Response(stream, {
    headers: {
      'Content-Type': 'text/event-stream',
      'Cache-Control': 'no-cache',
      'Connection': 'keep-alive',
    }
  })
}

// Client
const eventSource = new EventSource('/api/stream')
eventSource.onmessage = (event) => {
  console.log(event.data)
}
```

### 2. WebSockets

**Best for**: Bidirectional real-time communication (chat, collaboration)

```typescript
// WebSocket Server (Next.js with ws)
import { WebSocketServer } from 'ws'

const wss = new WebSocketServer({ port: 8080 })

wss.on('connection', (ws) => {
  ws.on('message', (data) => {
    // Broadcast to all clients
    wss.clients.forEach((client) => {
      if (client.readyState === WebSocket.OPEN) {
        client.send(data)
      }
    })
  })
})

// Client
const ws = new WebSocket('ws://localhost:8080')
ws.onmessage = (event) => console.log(event.data)
ws.send(JSON.stringify({ type: 'message', text: 'Hello' }))
```

### 3. ReadableStream API

**Best for**: Processing large data st