Frontends send requests to the GPU application, and GPU spreads their requests through the Gnutella network. Once results came back, GPU notifies the frontend9.
The following paragraphs come from "Getting the Message - Simple Techniques for Communicating Between Applications" by Robert Vivrette . You can refer to the source code simple_frontend.pas in the
Interprocess Communications is a broad description of any kind of communication between separate applications or processes. In particular, we will speak here about Windows messaging and Memory mapped files.