Understanding z/OS UNIX sockets and internetworking

z/OS® UNIX provides support for an enhanced version of an industry-accepted protocol for client/server communication known as sockets. The three types of application programming interfaces(API), for the sockets which will be covered in this topic are:

X/Open Socket: The API type of socket as defined by X/Open in XPG4.2.
Berkeley Socket: The socket API that represents a migration path for programs coded under the HOT1120 and HOT1130 elements. It allows use of the BSD4.3 interface and function in the X/Open environment. Its purpose is to expedite the porting of existing BSD4.3 applications.

The z/OS UNIX socket API provides support for both UNIX domain sockets and Internet domain sockets. UNIX domain sockets, or local sockets, allow interprocess communication within MVS independent of TCP/IP. Local sockets behave like traditional UNIX-domain sockets and allow processes to communicate with one another on a single system. Internet sockets allow application programs to communicate with others in the network using TCP/IP.

This topic provides some background information about z/OS UNIX sockets and about network communication in general. It is intended to provide an overview of the programming concepts associated with using z/OS UNIX sockets and network communication.

For information about using the socket API, see z/OS XL C/C++ Runtime Library Reference.