OASIS-MQTT-SPEC

OASIS MQTT lightweight IoT publish-subscribe messaging.

Definition

MQTT versions: MQTT 3.1.1 (October 2014, OASIS Standard, ISO/IEC 20922:2016, dominant deployments 80%), MQTT 5.0 (March 2019, OASIS Standard, enhancements). Architecture: Broker (Mosquitto, HiveMQ, EMQ X, AWS IoT Core, Azure IoT Hub, etc.) + Clients (publishers + subscribers). Hierarchical slash-separated topics ('/sensors/temperature/livingroom'). Wildcards: '+' single-level, '#' multi-level. QoS 0 (at-most-once fire-and-forget), QoS 1 (at-least-once acknowledged), QoS 2 (exactly-once 4-way handshake). Persistent Sessions, Retained Messages (last value retained for topic), Last Will Testament (LWT broker publishes if client disconnect ungracefully). MQTT 5.0 enhancements: User Properties (custom metadata), Reason Codes (verbose error feedback), Topic Aliases (bandwidth reduction), Session Expiry Interval, Server Disconnect with Reason. Transport: standard TCP, MQTT over WebSocket, MQTT-SN (Sensor Networks UDP), MQTT over TLS port 8883.

Origin

MQTT created 1999 by Andy Stanford-Clark IBM + Arlen Nipper Arcom Control Systems for oil pipelines SCADA telemetry ; donated OASIS 2013 ; MQTT 3.1.1 OASIS Standard 29 October 2014 ; MQTT 5.0 OASIS Standard 7 March 2019 ; ~5 billion devices deployment 2024.

Example in context

Tesla vehicles send telemetry (battery, navigation, vehicle state) via MQTT 5.0 to Tesla cloud servers AWS IoT Core: ~1 million vehicles publishing 100+ topics each, QoS 1, throughput ~50 billion messages/day.

Related terms

• OASIS AMQP — other OASIS messaging.