typedef MyQttQos(* MyQttOnSubscribeHandler)(MyQttCtx *ctx, MyQttConn *conn, const char *topic_filter, MyQttQos qos, axlPointer user_data)

Async notification handler that allows application level to control whether a subscription request should be accepted or not.

It can also be used as a way to track subscription taking place.

ctxThe context wherethe operation takes place.
connThe connection where the SUBSCRIBE request was received.
topic_filterThe topic filter requested on the SUBSCRIBE packet.
qosThe QOS value requested for this subscription.
user_dataUser defined pointer received on the function and provided at the configuration handler.