https://github.com/Azure/azure-iot-protocol-gateway/
"DotNetty only provides means to decode/encode traffic. Building a complete broker or client is out of scope really and properly implementing whole MQTT spec beyond parsing is too much for an example. That said, we've implemented MQTT spec (at least partially) in https://github.com/Azure/azure-iot-protocol-gateway/. It isn't true broker either but it does involve session management and things like maintaining order of ACKs."