MQTT plugin

[JEnoch]

Summary

A MQTT plugin for zenohd, in the same way than the DDS plugin.
Also available as a standalone zenoh-bridge-mqtt binary.

Intended outcome

A new Zenoh plugin (and standalone bridge) that will map the MQTT pub/sub to the Zenoh pub/sub.
Possible use cases:

• MQTT + Zenoh integration
• Routing MQTT from the device to the Edge and to the Cloud
• Bridging 2 distinct MQTT systems across the Internet, with NAT traversal
• Pub/sub to MQTT via the Zenoh REST API
• MQTT-DDS/ROS2 (robot) communication (via zenoh)
• MQTT record/replay with InfluxDB as a storage

How will it work?

Similarly architecture than the DDS plugin:
the discovery of MQTT publisher (or subscriber) will trigger in the plugin the creation of a matching MQTT subscriber (or publisher) and a corresponding Zenoh publisher (or subscriber)