This feature can be used if your device has an output and is capable to execute an order. So, you able to control your device remotely.
Device with MQTT protocol have different interface which user can add controller using MQTT broker.
Add New Controller
You can add a new controller as long as your device is able to execute an order.
1. Click on New Controller.
2. Give it a Name.
3. Set its Key, and Value.
4. Click Add Controller when done.