Can anyone recommend an MQTT client library for the Nano RP2040 Connect which deals with an intermittent connection in a reliable and non-blocking way?
Specifically, if QoS is 1 or 2, and the MQTT broker is not reachable when a publish call is made, I want the library to hold on to the message and transmit it at whatever later time the broker can be reached. I don't need the queue of untransmitted messages to be stored in non-volatile memory, though: I'm content to lose them if there's a power failure.
I've had a quick look at the code for a few MQTT libraries, and they mostly seem to either block if the server doesn't respond, or discard the message and fail. I think AsyncMQTT_Generic has the functionality I want, but it doesn't seem to support the Nano RP2040 Connect.
If it helps, I only need publish support, not subscribe.
TIA!
John