FlyveMDM takes benefit from the will and testament concept of MQTT protocol. When a client connects to the broker it can send a message to the broker. When the client hoes offline, the broker sends the message on behalf of the disconnected client.

The online status relies on will and testament feature of MQTT. When a device goes online, it must send

Sub topic /Status/Online

{"online": "true"}

When the device connects it must set a will and testmament message wich will fire to the backend from the Broker on behalf of the agent.

Sub topic /Status/Online

{"online": "false"}

This way, when the Broker detects loss of connectivity with an agent, it will inform the backend that the devices gone offline.