If method timeouts are defined somewhere in the spec please identify it. The only statement I can find in the spec about method timeouts is this: "Execution times for Methods may vary, depending on the function that they perform."

I have not found anything in the spec that offers a mechanism for a client to cancel, abort, or otherwise cause the termination of a call to a method other than terminating the session.

An operation can fail for all sorts of reasons, including the server taking so long to execute that the client no longer needs the result, even if the call were to eventually succeed. A method call that does not return may block the client from making other method calls until the current one completes - the server may only support one at at time, or the client may not support multiple calls on the same session.

Goals:
1) Client shall be able to cancel a method call while it is in-progress.
2) Client shall be able to specify an optional timeout value, after which the call to the server returns with a timeout error code. How to server handles the timeout condition is server specific - it can try to abort or otherwise cancel the call, let it run to completion and then not notify the client, etc.
3) Server may have its own timeout limit, in which case it may terminate a method call.

Error codes to be defined as needed to accurately specify the reason for the method failure.