MQTT

MQTT, formerly called Message Queuing Telemetry Transport, is a publish/subscribe messaging protocol for use over TCP/IP. MQTT is designed to ensure that devices can communicate with each other while minimizing power and bandwidth requirements. It is a simple messaging protocol that is well-suited for use with devices that rely on slow or unreliable networks.

The MQTT protocol is an application layer specification, and has been published as standard ISO/IEC PRF 20922. MQTT uses a Publish-Subscribe mechanism which requires a mediating broker. The publishers send data to the broker, and subscribing clients receive data published to the broker. Only clients that have subscribed to a particular topic receive messages about that topic. The protocol supports bidirectional communication such that a device that is a publisher can also receive updates.