Cooperating processes require an interprocess communication (IPC) mechanism
that will allow them to exchange data and information. There are two
fundamental models of interprocess communication: shared memoryand message
passing. In the shared-memory model, a region of memory that is shared
by cooperating processes is established. Processes can then exchange information
by reading and writing data to the shared region. In the message-passing
model, communication takes place by means of messages exchanged between
the cooperating processes. The two communications models are contrasted in
Figure 3.12.