> I think the proposal views the client like a workflow engine that calls
> upon the service to execute some process.
Exactly this is how workflows are to be done in RESTful applications,
according to Chapter 5.2 of Fielding's dissertation: The client has full
control where in the workflow it is ("State"), and selects from the URIs
which one to pick next to come to the next step. The server is stateless and
doesn't care about that current state in the workflow. That way, the server
can handle virtually infinite parallel workflow instances -- each driven by
a different client.