+−⟲ Mobile NLB WebSocketgatewaty Redis Workers publish response tosame channel X sub socket gateway channel 1socket gateway channel 2 WebSocketgatewaty WebSocketgatewaty WebSocketgatewaty Kafka publish pub msgs to queue consume ReserveProxy rate limitting LB for the proxy ssl termination sub to the gatewaychannel Resume session: Check the last request ID state on the BE, backend returns latest state of the old session Double sessions: Backend to support idempotency, if the FE does not get the response, it will ask the BE again avoid msg lost idempotent file_descriptor: Increase the max keeping connection for host Gateway, Worker, Reserve Proxy Websocket: Keeping connection by using Linux Socket I/O (networking connection) Each socket creates one File descriptor that is corresponded with each socket ID.