A system, device, and method for interprocessor communication in a computer system utilizes a special Message Passing Service (MPS) to provide interprocessor communications. The MPS enables a client application running on one processor in a computer to communicate with a target application running a different processor in the same or a different computer. In order for the client application to communicate with the target application, the client application establishes a session to the target application over an existing communication link using the MPS. The MPS provides for both synchronous and asynchronous communication services. When the client application establishes the session to the target application, the client application specifies, among other things, a "callback" routine. The MPS invokes the "callback" routine to report certain asynchronous events to the client application. The MPS blocks the client application during certain synchronous operations so that the client application does not proceed until the synchronous operation is completed.