Mastering Embedded Linux Programming - Second Edition

Message-based IPC

There are several options, which I will summarize as follows. The attributes that differentiate one from the other are as follows:

• Whether the message flow is uni- or bi-directorial.
• Whether the data flow is a byte stream with no message boundary or discrete messages with boundaries preserved. In the latter case, the maximum size of a message is important.
• Whether messages are tagged with a priority.

The following table summarizes these properties for FIFOs, sockets, and message queues:

Property	FIFO	Unix socket: stream	Unix socket: datagram	POSIX message queue
Message boundary	Byte stream	Byte stream	Discrete	Discrete
Uni/bi-directional	Uni	Bi	Uni	Uni
Max message size	Unlimited ...