{"id":"mqtt","model_id":"MQTT","name":"MQTT","summary":"MQTT is a lightweight publish/subscribe messaging protocol. Clients publish messages to named topics on a broker, and the broker forwards each message to every client subscribed to a matching topic. Sparkplug B is a specification layered on top of MQTT for industrial payloads.","study_notes":["Quality of Service levels: 0 delivers at most once, 1 at least once, 2 exactly once.","Topic filters use + for one level and # for all remaining levels."],"safety_notes":["Port 1883 is unencrypted. Use TLS on port 8883 and require client authentication on any broker reachable from outside the plant network."],"sources":[{"url":"https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=mqtt","title":"IANA Service Name and Transport Protocol Port Number Registry (mqtt, secure-mqtt)","accessed":"2026-10-25"},{"url":"https://docs.oasis-open.org/mqtt/mqtt/v5.0/mqtt-v5.0.html","title":"MQTT Version 5.0, OASIS Standard","accessed":"2026-10-25"}],"verification":{"status":"source_checked","checked_at":"2026-10-25","values":12,"method":"llm_source_check"},"updated_at":"2026-10-25","type":"protocol","spec":{"transports":["tcp","websocket"],"architecture":"publish_subscribe","encoding":"binary","default_ports":[{"port":1883,"transport":"tcp","secure":false,"purpose":"MQTT"},{"port":8883,"transport":"tcp","secure":true,"purpose":"MQTT over TLS"}],"data_types":[],"standard_body":"OASIS","standard_ref":"MQTT Version 5.0","related":["mqtt-sparkplug-b","mtconnect"]},"url":"https://machineschema.com/protocol/mqtt","license":"https://creativecommons.org/licenses/by/4.0/"}