If you will be using the TCP/IP socket API, also called non-Berkeley sockets,
you will need to read and understand this section.
When a
XL C/C++ application program running under
z/OS® UNIX needs to
communicate with another program that is running simultaneously, it
needs to exploit, from within itself, both
z/OS UNIX POSIX.1 and one or
more of the following application programming interfaces (APIs) provided
with the IBM® product TCP/IP:
- Socket APIs
- C sockets
- Inter-User Communication Vehicle (IUCV) sockets
- X Window System interface
- remote procedure call (RPC)
With the exception of described restrictions, you can code z/OS UNIX XL C/C++ application
programs to take advantage of the documented APIs available as part
of the Communications Server IP.
z/OS UNIX application programs can use socket API calls from the TCP/IP
product to access UNIX file system files or MVS data sets, communicate
with other systems running TCP/IP, or establish communication with
and request services from a workstation system acting as an X Windows
server.
Note: For UNIX file system file access to TCP/IP,
the TCP/IP socket API calls must be used instead of the POSIX file
access functions to preserve the uniqueness of file descriptors in
the UNIX file system.
Before you attempt to code your application program to use TCP/IP
APIs, you should understand the X Windows protocol running on the
workstations that will be used as application clients. You will also
need to know how to invoke X Windows to create a connection to the
server on the workstation or z/OS system.