Support for MQTT 5

[nullr0ute]

Is your feature request related to a problem? Please describe.
MQTT v5 is the latest version of the MQTT protocol.

Describe the solution you'd like
Adding v5 support to the existing MQTT protocol support so that there is one pub/sub client to support all version of the protocol.

Additional context
Version 5 of the MQTT protocol is published by OASIS at the following link:
https://docs.oasis-open.org/mqtt/mqtt/v5.0/mqtt-v5.0.html

The Eclipse PAHO project has open source client reference implementations supporting version 5 in a number of languages:
http://www.eclipse.org/paho/

[carlescufi]

@rlubos any plans to implement this in the near/mid term?

[rlubos]

@carlescufi Not on my schedule, at least for now. We might consider it though as it seems like a valuable improvement.

[Linutux]

I think MQTT 5 is particularly important for IoT devices, as it has some unique features, like "Maximum message size" or "Negative Acknowledgements", which tell the client why a massage could not be delivered.

[Aeted-RC]

Looking forward to implementing this plan, it is very meaningful

[troica65]

We are using MQTT client on a LInux system but want to move it to Zephyr in order to reduce COGS and Power consumption. Unfortunately Zephyr does not support 5.0 right now. Any plan for when it will

[rlubos]

As for Nordic, it's not on our schedule (yet), but other contributions are welcome.

[plskeggs]

@rlubos Amazon AWS now supports MQTT 5: https://docs.aws.amazon.com/iot/latest/developerguide/mqtt.html#mqtt5. The maximum packet size and receive maximum properties of the CONNECT packet are desirable.

[tka85]

Any upddate on this? Mqtt 5.0 is light years ahead of 3.1.1. They have added significant features that address all of the most common IoT pain points.

[rlubos]

Any upddate on this?

No progress according to my knowledge.

[iot-guy-col]

Any update on supporting MQTT 5? Is anyone using 3rd party libraries on Nordic microcontrollers?

[rlubos]

Any update on supporting MQTT 5?

No update.

[rlubos]

For anyone interested in the topic: #87354