FreeBSD provides a rich set of interprocess-communication facilities intended to support the construction of distributed and multiprocess programs built on top of communications primitives. Support for these facilities is described in this chapter.
No one mechanism can provide for all types of interprocess communication. The subsystems that provide IPC in FreeBSD 5.2 can be broken down into two areas. The first provides for IPC on a single system and includes support for semaphores,message queues, and shared memory. The second is the socket interface, which provides a uniform communication API for network communication.
The socket API is deeply entwined with the network subsystem. The architecture of the network system is described in Chapter 12, and the networking protocols themselves are examined in Chapter 13. You will find it easiest to understand the material in these three chapters if you read this chapter before you read Chapters 12 and 13. At the end of Chapter 13 is a section devoted to tying everything together.
