We are working on adding MQTT v5.0 support to wolfMQTT.
Some of the new MQTT 5 features include:
- AUTH packet type to submit authentication method/data information after connect.
- CONNACK packets now include a reason code to better describe connect failures.
- DISCONNECT now supports server to client.
- Packets can include optional key/value properties.
- New data type for UTF-8 string pairs.
- No retry for QoS 1 and 2 packets (let assumed TCP handle retry).
- Passwords can be provided without a username
The new specification can be found here:
http://docs.oasis-open.org/mqtt/mqtt/v5.0/mqtt-v5.0.html
Support for these new features will be release in the next few weeks as wolfMQTT v1.0.