Re: [mqtt-comment] User Properties in PubAck, PubRec, PubRel, PubComp Packets

[Christoph Krey <c@ckrey.de>]

I'm just working through implementing v5 in the Paho Java client and I've just got round to the Ack/Rec/Rel/Comp packets.

Good news, I am close to finish implementing v5 in MQTTClient for iOS and a small private test broker. Anybody else already started implementing V5
ready to share for interoperability tests?

Does anyone have any use cases for the User Properties in these packets?

TBH, no idea

I'm curious how these properties should be exposed to the client application for both inbound and outbound messages (if they even are) and could do with an example to two so that I can get it right.

I would do it as follows:

If an outgoing PUBLISH is succeeds, provide the User Properties of the last step to the "message delivered" callback with the Reason Code and Reason String.

If the outgoing PUBLISH fails, provide the User Properties with the Reason Code and Reason String of the last step to the "message failed" callback.

If an incoming PUBLISH fails, just log the User Properties with the Reason Code and Reason String.

Christoph