For me this interesting if i m interested in sending behavior to Arduino, but lets take the following scenario, sending the commands is too slow for your need a

For me this interesting if i m interested in sending behavior to Arduino, but lets take the following scenario, sending the commands is too slow for your need and all you need is to remote control your Arduino, then in this case you can follow the same design, redefine new messages in Protobuf and a way of reacting to them in Arduino, apart from this Firmata seems much mature.