- Is there any acknowledge/reply message from the box when we submit commands?
No there is no acknowledge message.
*On MQTT, a command is acknowledged at a protocol level, indicating the command was received by the box or not
- Is there any kind of feedback about the command execution?
An error event is fired each time a command fails, or in case of other errors
- Can we know the status of a connected device (on/off, % of dimmering)?
You will have to define a property for that purpose on that device.
- Is there a possibility to group multiple commands together in the configuration of the box?
Each command is managed independently, you must send individual commands.
- Does Wattsense box need keepalive messages from our device? If yes in which format?
No need for the box to receive keepalive messages.
- Can Wattsense box provide the current status of a connected device on request?
Just read the property you defined for this purpose on the device.
- What are the policies about firmware upgrades of the box ? Should we consider changes in the interaction via MQTT protocol in the future?
The MQTT data model is not intended to change, we will keep the upward com patibility. The desktop config application will tell you whether a new firmware version is available, what is its purpose (features, bugfixes) and will propose to do the update.