What it is and the problem it solves
MQTT is a lightweight, publish–subscribe machine-to-machine protocol. It solves the problem of sending telemetry from battery-powered, bandwidth-constrained devices — like oil pipeline sensors linked via expensive satellite — where HTTP or TCP sockets would waste power and money.
How it works
MQTT uses a publish–subscribe mechanism over TCP/IP. A central broker routes messages from publishers to subscribers. Devices send small, structured packets with minimal overhead. It requires ordered, lossless, bi-directional transport — so it cannot run directly on UDP or lossy radio links.
What works
The publish–subscribe model reduces network chatter. Small fixed-header packets (as little as two bytes) cut bandwidth use. Its simplicity allows implementation on microcontrollers with under 10KB RAM. It works reliably over high-latency satellite links when configured for QoS 1.
What does not
MQTT does not provide built-in encryption, authentication, or access control. It does not guarantee message ordering across topics or delivery timing. It assumes a stable TCP connection — so it fails under frequent disconnections without client-side reconnection logic.
What it changes
It shifts IoT architecture from point-to-point polling to event-driven, decoupled messaging. It enables many-to-many telemetry at low bandwidth cost — but locks deployments into a centralised broker model that scales poorly in distributed edge environments.
Is it worth your time
Yes — if you are building telemetry systems for constrained devices and need interoperability across vendors. No — if you require strong security by default, real-time guarantees, or peer-to-peer operation without a broker.
