Different processes can pass information among themselves using a special
feature of the operating system, referred to as Interprocess Communication
(IPC). Large tasks that have been broken into independent processes can use
IPC to synchronize their actions and exchange data with other processes. There
are several ways you can implement IPC on MPE/iX:
Using file system intrinsics and message files
Using session-level variables and Job Control Words (JCWs)
Using process management mail intrinsics
The file system intrinsics HPFOPEN,FOPEN,FREAD,and FWRITE provide the most
powerful method of performing IPC. These intrinsics can be used to communicate
between any user process; the processes do not need to be in the same process
tree, or running in the same job or session.
Processes executing in the same job or session can use a session-level variable
or JCW to pass smaller amounts of data more efficiently than using message
files.
Some older applications use the "mail" facility to communicate between
processes in the same process tree (same job or session). Each process in the
process tree can use this facility to pass information between itself and
either its parent or child process.
For more information about using IPC features to provide communication between
processes, refer to Interprocess Communication Programmer's Guide
(32650-90019).
