James,
Interesting extension that kind of cross over to discovery (what can this service do?)… but then you have discovery documents for that.
One thing that I have been considering is beyond activities, you may want to consider the product that may be generated as a result of that activity being performed.
Sometime you may need more than one activity to generate a significant product… so you may need to define a behavior or sequence of activities to be initiated at the user level… with activities actually running on the specified servers.
Behaviors can be defined in Javascript and served as code on demand to the client… to generate a product of interest… on-demand.
So think of users searching for a specific product and receiving potential behaviors from multiple servers.
Users could execute the preferred behavior based on some constraints (cost, location, speed…)… which generates an activity stream… that can be duplicated by friends interested in similar products… :)
This would be REST level 5 :)…
Interesting?
Cheers,
Pat.