The MQTT protocol is a lightweight network protocol used for publish/subscribe messaging, optimized for wireless remote devices that might have limited bandwidth and intermittent connectivity. This appendix describes the following concepts about the MQTT protocol:
â¢Quality of service (QoS) levels and flows
â¢QoS effect on performance
â¢Durable and non-durable subscribers
â¢Retry message delivery
â¢Last Will and Testament
â¢Retained flag on messages ...