Comment:

These resources overlap in functionality with Task and with standard RESTful query capabilities. Cancel is a type of task. A request to cancel a prescription, lab order or to initiate discharge proceedings for an Encounter would be handled as a Task. Cancelling a Claim or other financial event should be no different. Requesting re-processing (re-execution of an operation) can also be performed using Task. Where business processing has been requested, Task represents that fulfillment process and can thus convey the business state of execution. As such "status" is inappropriate either - just query for the Task associated with processing the request - as is done for all other workflows. Finally, polling is a type of query and should use either the RESTful query mechanism or an operation, not a resource.

Summary:

ProcessRequest/ProcessResponse should not exist