Server-Sent Events (SSE)

Push real-time updates to browsers over standard HTTP with a built-in, zero-dependency SSE broker.

Features

• Global broker available on every app: app.SSE
• Broadcast to all connected clients or send to a specific client
• JSON helper: app.SSEBroadcastJSON(event, payload) marshals a payload and broadcasts it
• Automatic client disconnect detection via request context cancellation
• Works through the existing middleware stack (RequestID, CORS, SecurityHeaders, SessionLoad, etc.)
• Generated apps include a visual SSE demo on the home page (/sse/stream and /sse/ping)

Usage

// Broadcast a JSON event to every connected browser
_ = app.SSEBroadcastJSON("notification", map[string]string{
    "message": "Hello, world!",
})

// Or build an event manually and broadcast it
app.SSE.Broadcast(regius.SSEEvent{
    Event: "notification",
    Data:  []byte(`{"message":"Hello, world!"}`),
})

// Stream events from a handler
r.Get("/sse/stream", app.SSE.Handler())

Event Structure

config := regius.SSEEvent{
    ID:    "1",                   // Optional event id for the Last-Event-ID header
    Event: "update",              // Event name listeners can subscribe to
    Data:  []byte(`{"ok":true}`), // Raw event payload
    Retry: 3000,                  // Optional reconnection time in milliseconds
}

Environment Variables

# Disable the demo heartbeat in generated apps (disabled by default)
SSE_DEMO_HEARTBEAT=false