5) Inter-Process Communication (IPC)

~ Mechanism for processes to communicate and to synchronize their actions

~ Message system – processes communicate with each other without resorting to shared variables

~ IPC facility provides two operations:
>> send(message) – message size fixed or variable
>> receive(message)

~ If P and Q wish to communicate, they need to:
>> establish a communication link between them
>> exchange messages via send/receive

~ Implementation of communication link
>> physical (e.g., shared memory, hardware bus)
>> logical (e.g., logical properties)