How FEPI fits into your system
FEPI allows CICS front-end application programs to communicate with unchanged back-end applications running on CICS or IMS systems that are local or remote. The back-end applications continue to work just as if they are being accessed from the type of terminal they were originally written for.
A FEPI application is a CICS application that is designed to use FEPI to communicate with existing back-end applications. It is also known as a terminal front-end program.
The front end is the system on which the FEPI application runs, and the back end is the system on which the existing application runs. (They can run in the same CICS region.)
Figure 1 shows how FEPI links the unchanged back-end applications to the new CICS® FEPI applications. To an existing application, the front-end application looks like a terminal.