CueProxy Overview
CueProxy is the stateless HTTP and WebSocket gateway for Cue.
- Completely stateless & horizontally scalable
- Handles authentication, load balances outflow to consumers subscribed to a topic, and applies backpressure
- Proxies communicate with Cue via QUIC
Architecture
Proxy Components and Flows
1. Producer Add Topic Flow (Synchronous)
| Step | Direction | Action | Protocol |
|---|---|---|---|
| 1 | Producer → API | Send add topic request | HTTP |
| 2 | API → Cluster Agent | Forward request | Internal |
| 3 | Cluster Agent → Leader | Propose topic creation | QUIC |
| 4 | Leader → Cluster Agent | Topic created response | QUIC |
| 5 | Cluster Agent → API | Pass response back | Internal |
| 6 | API → Producer | Return success/failure | HTTP |
2. Producer Add Job Flow (Synchronous)
| Step | Direction | Action | Protocol |
|---|---|---|---|
| 1 | Producer → API | Send add job request | HTTP |
| 2 | API → Cluster Agent | Forward request | Internal |
| 3 | Cluster Agent → Leader | Propose write to Raft | QUIC |
| 4 | Leader → Cluster Agent | Job committed response | QUIC |
| 5 | Cluster Agent → API | Pass response back | Internal |
| 6 | API → Producer | Return ACK | HTTP |
3. Consumer Subscribe & Job Dispatch Flow (Asynchronous)
| Step | Direction | Action | Protocol |
|---|---|---|---|
| 1 | Consumer → API | Subscribe to topic | WebSocket |
| 2 | API → Consumer | Subscription confirmed | WebSocket |
| 3 | Leader → Cluster Agent | Dispatched jobs | QUIC |
| 4 | Cluster Agent → API | Pass jobs | Internal |
| 5 | API → Consumer(s) | Deliver job (load balanced by topic) | WebSocket |
| 6 | Consumer → API | Process ACK | WebSocket |