Request/Response

While with MQTT3 a request/response procedure still had to be implemented manually by corresponding, applicative handshake mechanisms of the MQTT clients, MQTT5 now offers a native implementation for this. The procedure is based on the fundamental assumption that the sender of a request defines a so-called "response topic" and sends it as part of the message. The recipient of the request can then use this response topic to send its response. The following figure illustrates this process.