Design overview

The CICS® code that processes external call interface (ECI) requests that arrive from a TCP/IP network via the Sockets Domain (SO) is mostly contained within the IP ECI (IE) domain. Some code that is logically part of the function runs in AP domain.

SO domain works by attaching a listener task (CIEP for IPECI) to handle incoming data, and IE domain attaches a mirror task (CPMI) to issue the program link request and return any resulting output.

There are five logically separate pieces of code for this function:
  • IE domain initialization and termination code in DFHIEDM.
  • The AP domain part of the listener task, in program DFHIEP.
  • The IE domain part of the listener task, in the PROCESS_ECI_FLOW function of program DFHIEIE.
  • The AP domain part of the mirror task, in programs DFHMIRS and DFHIEXM.
  • The IE domain part of the mirror task, in the SEND, RECEIVE and SEND_ERROR functions of program DFHIEIE.
See IP ECI (IE) domain for more information.