WebSockets and SSE Patterns

Real-time communication patterns for FastAPI: WebSockets for bidirectional, SSE for server-push.

When to Activate

• Building real-time features (live updates, streaming LLM output, notifications)
• Choosing between WebSockets and SSE for a use case
• Implementing connection management (connect/disconnect, broadcast)
• Scaling real-time across multiple workers with Redis
• Handling backpressure or slow consumers disconnecting other clients
• Writing tests for SSE or WebSocket endpoints
• Implementing Node.js server-side WebSocket handling
• Debugging connection drops, backpressure, or missed events
• Implementing heartbeats and client-side reconnection

WebSocket vs SSE — When to Use Which