Identify the process ID of the client process communicating with the COM RPC server

Question

In the COM RPC model, if the server is running in a separate process, is it possible to find out what is the process identifier of the client process interacting with the server?

Use case

I have an Out Process RPC server that can receive a request from one or more client processes. Sometimes the server needs to know the client process to write data back to the client address space using Write Process Memory .

Also note that the API signatures, the way the buffer is allocated, and the appearance of the APIs are out of my control.