Message Queuing Telemetry Transport MQTT is a bi-directional lightweight network communication protocol protocol that transports messages between low power devices and can run over TCP/IP. The MQTT protocol is based on the principle of publishing messages and subscribing to topics to exchange data between clients and the server.
Example:
Temperature sensor: This sensor publish a value 20 Celsius degrees to the Mqtt Broker. A device that needs that value must subscribe to the Mqtt Broker to receive it. The temperature sensor is the publisher and the mobile the Subscriber.
A client can subscribe to individual or multiple topics.
Example:
Topics:
house/groundfloor/livingroom/temperature
house/groundfloor/livingroom/lightswitch
house/groundfloor/garage/temperature
house/firstfloor/bedroom/temperature
There is a multi-level wildcard # and a singel-level wildcard +
Green: Does receive Publisher messages.
Red: Does not receive Publisher messages.
house/# produce the following results:
house/groundfloor/livingroom/temperature
house/groundfloor/livingroom/lightswitch
house/groundfloor/garage/temperature
house/firstfloor/bedroom/temperature
house/groundfloor/# produce the following results:
house/groundfloor/livingroom/temperature
house/groundfloor/livingroom/lightswitch
house/groundfloor/garage/temperature
house/firstfloor/bedroom/temperature
house/groundfloor/+/temperature produce the following results:
house/groundfloor/livingroom/temperature
house/groundfloor/livingroom/lightswitch
house/groundfloor/garage/temperature
house/firstfloor/bedroom/temperature
