When Unexpected Things Happen to Good Messages

IMS continues to be a robust, reliable data server of choice in the enterprise; its ability to flawlessly execute billions of transactions provides evidence of its staying power. IMS prevails because it is reliable, dependable, and it works. Legacy applications and data persist because IBM continues investing in IMS and enhancing its functionality. The additional investment allows IMS to keep pace with the times, so that new interfaces and subsystems can access applications and data.

With the evolution of IMS in the enterprise, not only have the formats and structures of the databases changed, but so too has the, often overlooked, messaging environment. Because of data interface and access improvements, IMS is now open to access from other subsystems and the Web. IMS has evolved from local queues to shared queues, and now processes message types including Advanced Program-to-Program Communication (APPC) and Open Transaction Manager Access (OTMA) from other subsystems. Ongoing improvements to operating system architecture and hardware performance have permitted increased workloads and improved throughput in IMS. As a consequence, the amount of message traffic that must flow through the message queue has increased. The architecture changes, new interfaces, and additional traffic have created further dependence on message queue availability and performance. The availability of the IMS message queues has become as critical as the availability of the IMS databases.

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