Communicating over MQTT
MQTT, the
Message
Queuing
Telemetry
Transport protocol is the communication protocol of choice in many IoT applications. It uses a broker receiving subscriptions and publications, distributing messages on a certain topic to everybody subscribed to to it. It is a light weight protocol running of top of TCP.
Below we see an example running mosquitto, the MQTT broker, 2 nodes (mosquitto_sub) have subscribed to the topic AFNOG19 and AFNOG18 respectively.. When a third node publishes information on the topic AFNOG19, then the first subscriber receives the information while when publishing on AFNOG18 it is the second subscriber seeing the message.
MQTT and Cayenne
Cayenne supplies an mqtt broker at mqtt.mydevices.com which uses a strict format for the topic and the payload string. When registering at
MyDevices Cayenne as a new user you will be attributed a
username and a
password. For each device you register you will get a
device_id.
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Uli Raich - 2019-04-09
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