How FEPI fits into your system

Figure 1 shows the relationship between FEPI and other components of your system. Note, particularly, the unchanged applications in the lower part of the figure, and the new CICS® FEPI application near the top. To an existing application, the front-end application looks like a terminal.

Figure 1. Structure of FEPI and application programs
 The picture shows two back-end systems, one IMS, the other CICS. On each back-end system there is an unchanged application. The back-end systems use VTAM to communicate with a front-end CICS system on which a new FEPI application runs. To the back-end unchanged applications, the front-end FEPI application looks like a terminal.

Now some definitions: the front end is the system on which the CICS FEPI application runs, and the back end is the system on which the existing application runs. (They may be the same 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 CICS 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.

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