SSE (Server-Sent Events)

Unidirectional push from server to clients over standard HTTP. Clients open a GET request and receive a continuous text/event-stream response — no WebSocket handshake, no custom protocol, just plain HTTP that works through proxies and firewalls. Use it for live feeds, progress tracking, notification banners, or any scenario where the server pushes updates and clients only listen.

Configuration

connector "sse" {
  type = "sse"
  port = 3002
  path = "/events"

  heartbeat_interval = "30s"

  cors {
    allowed_origins = ["https://app.example.com"]
  }
}

Option	Type	Default	Description
port	int	—	Listen port
host	string	"0.0.0.0"	Bind address
path	string	"/events"	SSE endpoint path
heartbeat_interval	duration	"30s"	Keepalive comment interval
cors.allowed_origins	list	—	Allowed CORS origins

Operations

Target only — clients connect via GET, the server pushes events.

Operation	Direction	Description
broadcast	target	Send to all connected clients
send_to_room	target	Send to clients in a specific room
send_to_user	target	Send to a specific user

Client Connection

Clients connect via GET /events with optional query parameters:

Parameter	Description
?room=orders	Join a single room
?rooms=orders,inventory	Join multiple rooms
?user_id=42	Per-user targeting

The connector sends periodic heartbeat comments (: keepalive) to keep connections alive through proxies.

Example

# Broadcast to all connected clients
flow "live_feed" {
  from {
    connector = "rabbit"
    operation = "feed.item"
  }
  to {
    connector = "sse"
    operation = "broadcast"
  }
}

# Push only to clients subscribed to a specific room
flow "room_updates" {
  from {
    connector = "rabbit"
    operation = "room.event"
  }
  to {
    connector = "sse"
    operation = "send_to_room"
    target    = "input.room"
  }
}

# Push to a single user
flow "user_notification" {
  from {
    connector = "rabbit"
    operation = "notification.personal"
  }
  to {
    connector = "sse"
    operation = "send_to_user"
    target    = "input.user_id"
  }
}

See the sse example for a complete working setup.

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Full configuration reference: See SSE in the Configuration Reference.