SupportPac CA1T: High availability exits for use with CICS TG

SupportPac CA1T provides sample exits to enable a high availability infrastructure to be created quickly, using rules defined in a simple text based configuration file. On z/OS, a highly available Gateway group can be sysplex-wide, presenting a single entry point to external applications, backed by multiple Gateway daemons and CICS regions acting as together. These rules define a set of policies to validate and workload balance External Call Interface (ECI) requests across defined CICS servers, providing increased availability to CICS applications accessed from remote clients using the facilities of the CICS TG.

Version 1 of this SupportPac provides a set of sample CICS request exits to be used with the CICS Transaction Gateway for z/OS V7.2. Three different CICS request exit implementations are provided to perform either round-robin or failover-based workload balancing, or alternatively perform request validation. Only one CICS request exit can be deployed at any one time, and each exit must be configured using an HFS configuration file as described in the supplied documentation.

Version 3 of this SupportPac provides a combined validation and workload balancing infrastructure to be used with:

• CICS Transaction Gateway for z/OS V8.0, or later
• CICS Transaction Gateway for Multiplatforms V8.1, or later
• CICS Transaction Gateway Desktop Edition V8.1, or later

Note: Version 3 of this SupportPac supersedes Version 2, but remains fully compatible. The same configuration file from CA1T V2.x can be used with CA1T V3.x.

Configuration is based on a flexible set of rules defined in a configuration file. On z/OS, the configuration file can reside either on HFS or in an MVS dataset. Rules for workload balancing can be generic per Gateway, based on server aliases, or on the payload type (for example, channel or commarea). Rules for request validation can be specified based on user IDs, transaction IDs, or program names, and operate as either a allowlist (INCLUSIVE) or blocklist (EXCLUSIVE). All rules can be dynamically updated while the Gateway daemon is running. A configurable retry interval is provided to improve the efficiency of request distribution when using workload balancing.

New in release V3.0.0:

• EXCLUSIVE validation mode that allows ECI requests to be rejected based on user ID, transaction ID, or program name
• Support for CICS TG for Multiplatforms V8.1, or later
• Support for CICS TG Desktop Edition V8.1, or later

What's new in this release (V3.0.1)?

• Added support for CICS TG V9.1

Possible Uses
Creation of CICS Transaction Gateway high availability configurations or request validation policies.

Skill level required
System administrator with understanding of the configuration of the CICS Transaction Gateway.

Details
Authors: Andrew Smithson, Phil Wakelin, and Rob Jones. CICS TG Development, Hursley
Category: 2
Released: 16Jul10
Last updated: 29Sep14
Current Version: V3.0.1