networks//network protocols//MQTT

A lightweight publish-subscribe protocol over TCP/IP, built for telemetry and events. A producer publishes to a topic on a broker; any number of clients subscribe to that topic and receive the message. The producer never needs to know who consumes.

A lightweight publish-subscribe protocol over TCP/IP, built for telemetry and events. A producer publishes to a topic on a broker; any number of clients subscribe to that topic and receive the message. The producer never needs to know who consumes.

Born for constrained devices and unreliable links, which is why it fits IoT and the industrial edge: small headers, keep-alive, quality-of-service levels for delivery guarantees, retained messages and last-will announcements when a client drops.

What it is for and what it is not: MQTT distributes information between systems; it does not read or write a device's registers, and it was not designed to move a robot axis. In a plant it sits on the IT side of the boundary, fed by a gateway that speaks the fieldbuses (MQTT).

Compared with raw TCP sockets, UDP or SSH tunnels, the point of MQTT is decoupling: A and B both know the broker and nothing about each other.