3.1.4 Message Processing Events and Sequencing Rules
No sequence of method calls is imposed on this protocol.
When a method completes, the values that the RPC returns MUST be returned unmodified to the upper layer.
The client MUST ignore errors that the RPC server returns and notify the application invoker of the error received in the higher layer. Otherwise, no special message processing is required on the client beyond the processing required in the underlying RPC protocol.