requirements.txt

1. Client → API Server:
   The client sends a request (e.g. buy stock).

2. API Server → Redis Request Queue:
   The API server pushes the task to the Redis request queue.

3. Worker Engine → Redis Response Pub/Sub:
   The Worker Engine picks up the task, processes it (updates the orderbook), and publishes the result to the Redis response pub/sub.

4. Redis Pub/Sub → API Server:
   The API server listens to the Redis response Pub/Sub, picks up the result, and sends the response back to the client.

5. Redis Response Pub/Sub → WebSocket Server:
   The WebSocket server also listens to the Redis response pub/sub. When an updated orderbook is available, it broadcasts the orderbook of that particular stock symbol to all connected WebSocket clients.