Indeed; I was thinking the same. That could easily drain a hub's
bandwidth. Since it's rather clearly defined anyway which commands
will ever need a similar "upgrade", I'd say that it's better in that
case to make those commands generic enough to be upgraded easily.

I have a better choice. Let's define only one command (*) having various parameters (in random order) and let the hub randomly chooses the action to do with this command. It is the perfect protocol: no out of order problem, low bandwidth usage for both hub and client, and finally, random results (like any P2P protocol)... oh, I have forgotten how it will be easy to program because due to the fact everything is random, you can program the code you want :)

Eric