Server-Sent Events (SSE)

Tainha supports proxying Server-Sent Events from your backend to clients. When a route is marked as isSSE: true, the gateway streams the response directly without buffering.

Configuration

routes:
  - method: GET
    route: /events
    service: localhost:3001
    path: /sse
    isSSE: true
    public: true

How It Works

For SSE routes, the gateway:

1. Receives the client connection
2. Sets CORS headers for cross-origin streaming
3. Proxies the request directly to the backend
4. Streams the response in real-time (no buffering or recording)

Key Differences from Regular Routes

	Regular Routes	SSE Routes
Response	Buffered, then sent	Streamed in real-time
Mapping	Supported	Not supported
CORS	Via middleware	Extra headers added
Connection	Short-lived	Long-lived

Example Backend

A minimal SSE server in Go:

func sseHandler(w http.ResponseWriter, r *http.Request) {
    w.Header().Set("Content-Type", "text/event-stream")
    w.Header().Set("Cache-Control", "no-cache")
    w.Header().Set("Connection", "keep-alive")

    flusher := w.(http.Flusher)

    for i := 0; i < 10; i++ {
        fmt.Fprintf(w, "data: {\"count\": %d}\n\n", i)
        flusher.Flush()
        time.Sleep(1 * time.Second)
    }
}

Notes

• SSE routes skip response mapping (the response is streamed, not buffered)
• Authentication still works on SSE routes (unless marked as public: true)
• The gateway adds CORS headers to support cross-origin SSE clients