[paho-dev] How does MQTT-SN Client tell its been disconnected?

[Paul Kierstead <paulkierstead@xxxxxxxxx>]

Lets say the GW has been power cycled, crashed or, for that matter, rebuilt. The client sends a PUBLISH, or perhaps even a PING. How can the gateway inform the client that it is not connected? The return codes for publish do not seem to allow for a "I don't know who the hell you are" code. I guess, in the case of PING, the gateway could just decline to answer, and eventually the client would get the idea. If the client is primarily a subscriber, it would be worse; it could basically wait there for ever for a publish that is not forth coming. In theory it would ping the gateway for keep-alive, and it would get back to the above ping response. I suspect there is something I've glossed over in the protocol.

My apologies if a protocol discussion doesn't fit into 'dev'; I wasn't sure.

PK