Abstract for IP IMS Sockets Guide

Purpose of this information

This information describes how to use IP Services with IMS™ Version 7 and later. It describes the IMS call interface and the supporting functions. The information supports both IPv6 and IPv4. Unless explicitly noted, information describes IPv4 networking protocol. IPv6 support is qualified within the text.

This information addresses the following topics:

IMS client/server application design
The IMS Listener
The IMS Assist function
The IMS socket calls, including call syntax conventions

Who should use this information

This information is intended for programmers who have some familiarity with IMS Transaction Manager and IP Services, and who need to develop IMS client/server applications.

To ensure proper interprogram communication, the two halves of a client/server program must be developed together. At a minimum, they must agree on protocol and data formats. To complicate matters (particularly in the case of a UNIX processor talking to an IMS mainframe), the technology differences are so extensive that the two halves will often be coded by different individuals — one, an IP socket programmer; the other, an IMS programmer.

This information has been designed for users with a variety of backgrounds and needs:

Application designers need to know how the various components of IMS TCP/IP interact to provide program-to-program communication. These readers should read Principles of operation of the Listener and the Assist module.
Experienced IP socket programmers need to know the protocol and message formats necessary to establish communication with the IMS Listener and with the server program. These readers should read How to write an IMS TCP/IP client program and CALL instruction application programming interface.
Experienced IMS application programmers will be familiar with IMS input/output calls (GU, GN, ISRT). These programmers have two choices:
- Programmers with IMS experience and little or no TCP/IP programming experience will probably want to use the IMS Assist module, which accepts standard IMS I/O calls, and converts them to equivalent socket calls. They should read the sections on implicit-mode programming.
- IMS programmers with socket experience can choose to code native C language or use the Sockets Extended API. These programmers should read the sections on explicit-mode programming and CALL instruction application programming interface.
IMS system programmers and communication programmers are responsible for the IMS system itself. These readers should read How to customize and operate the IMS Listener.