Summary

Message passing is an extremely powerful concept and is one of the main features on which Neutrino (and indeed, all past QNX operating systems) is built.

With message passing, a client and a server exchange messages (thread-to-thread in the same process, thread-to-thread in different processes on the same node, or thread-to-thread in different processes on different nodes in a network). The client sends a message and blocks until the server receives the message, processes it, and replies to the client.

The main advantages of message passing are:

• The content of a message doesn't change based on the location of the destination (local versus networked).
• A message provides a "clean" decoupling point for clients and servers.
• Implicit synchronization and serialization helps simplify the design of your applications.