IMS Transaction Manager: From Its Moonshot Roots to More Recent Product Enhancements
In this installment of "z/OS and Friends," Joe Gulla examines IMS Transaction Manager's beginnings, then considers how modern enhancements continue to make it an important component of z/OS
In the first “z/OS and Friends” article on Information Management System (IMS), the focus was the IMS database component (IMS DB). There is, however, another important component focused on transaction management. In this article, I will discuss IMS Transaction Manager (IMS TM), as it is the engine that supports database processing. I will also explore recent enhancements that center on making the most of distributed computing innovations. First, let me share some IMS history.
History of the IMS Product
In 1961, President Kennedy challenged American industry to send an American to the moon. American Rockwell won the bid to build the spacecraft and they made a partnership with IBM in 1965. The partnership was to create a computer system to manage large bills of material for the spacecraft. In 1966, members of the IBM team, along with members from American Rockwell and Caterpillar Tractor, began to design and develop the system that was called Information Control System and Data Language/Interface (ICS/DL/I).
In 1967, the IBM team completed and shipped the first release of ICS, and in 1968, ICS was installed and the first “READY” message was displayed on an IBM 2740 typewriter terminal at the Rockwell Space Division. In 1969, ICS was renamed to Information Management System/360 (IMS/360) and became available to the IT world. IMS helped to start the database management system revolution and continues to evolve to meet the data processing requirements of today’s businesses and governments. A few more details are available here about the history of the IBM product that became IMS.
System With 2 Main Parts
The two parts are right there in the middle of the Figure 1—Transaction Manager and Data Database Manager.
IMS has a stated purpose; that is, to run as a platform built for high performance. A big part of the product is IMS TM, a message-based transaction processor. IMS TM provides services to process input messages received from a variety of sources, like the terminal network, other IMS systems and the web. IMS TM also processes output messages created by application programs. The approach to the processing is an underlying queueing mechanism for handling these messages.
IMS TM supports many terminal sessions at very high transaction volumes. The users of the terminal sessions can be people at terminals or workstations, as well as other application programs. These other application programs can be either on the same z/OS system, on other z/OS systems or on non-z/OS platforms. Basic ideas about IMS TM are summarized in Figure 2, below.
Transaction Manager and the Queueing Technical Topic
How widespread is this queueing approach used with IMS TM? Placing a focus on input and output messages to process work in a system has a lot of support in the technical literature. It should come as no surprise that it is a highly successful way to process data very quickly. I went to ScienceDIrect.com and searched on “Transaction Manager” and was given 12 pages of chapters and articles on the topic from 2003 to the present. Not every chapter and article were applicable to IMS, but many were. The search results indicated that the research area has vitality and proven results.
Multiplicity Is a Good Thing When It Comes to Processing Options
IMS application implementations can specify a variety of online processing profiles. For example, you can define transactions for high-volume data-entry applications, others for interactive applications and still others to support predefined queries. IMS TM also makes it possible to develop a wide range of high-volume, rapid-response applications, and to geographically disperse the data processing locations while keeping centralized control of the database. With so many options comes choice in designing an application that meets very specific needs.
No Suprise, TM Works Well With DBs
When IMS TM is used with a database manager, IMS TM extends the capabilities of the database manager to the real-time environment. IMS TM enables terminals, other devices and subsystems to enter transactions that initiate application programs, which access IMS DB or DB2 databases and return results.
The Software Support You Get From the IMS Team
Like CICS, IMS has not rested on its past achievements. Here is a discussion of the key supported software products.
Languages
IMS supports a wide variety of programming languages including Ada, COBOL for OS/390 and VM, and Enterprise COBOL for z/OS. Also, Enterprise PL/I for z/OS, IBM High Level Assembler for z/OS and z/VM & z/VSE, Java, using the IBM SDK for z/OS, PL/I for z/OS and OS/390, TSO/E REXX, VS Pascal and z/OS C/C++.
Language support matters because different organizations often have a programming language legacy, so flexible options are important. Also, younger programmers often have a significant interest in newer languages. They don’t want to be left out as they make early career moves to gain experience.
WebSphere
IMS supports WebSphere Application Server (WAS) and WebSphere MQ. WAS matters because its programming model for applications deployed on the product utilize Java specifications and other open standards for developing applications. Also, the WAS programming model extensions enhance application functionality. Using it gets you a significant jump on utilizing open technologies.
WebSphere MQ is used for reliable, secure and asynchronous messaging between applications, especially when those applications are geographically dispersed or have different operating systems. This is useful because MQ can be used on more than 35 hardware platforms and for point-to-point messaging from Java, C, C++ and COBOL applications.
CICS Transaction Server
CICS works with IMS DB and can run concurrently with IMS TM. IBM CICS Transaction Server (CICS TS) for z/OS can connect to IMS if the minimum version requirements are met. This is significant because it opens the door to broad integration. For example, when two companies merge, they may have different software use history or preferences. A CICS TS use legacy can blend with an IMS DB preference through built-in integration capability.
Transaction Manager
IMS Transaction Manager can connect with Db2 for z/OS. This is useful if you have an IMS TM legacy with IMS DB and you acquire an application that utilizes Db2. This ability to connect opens the door to desired (or needed) integration.
Internal Resource Lock Manager
The Internal Resource Lock Manager (IRLM) is an integral part of IMS. After taking the necessary installation steps, it is available for use to perform block-level or sysplex data sharing. IRLM is also the required lock manager for DB2 UDB for z/OS.
What is There in Addition to Software Support?
Beyond software support as discussed, IMS can perhaps be better understood by exploring the following four topic areas—resources, education, downloads and IMS tools.
Resources
The IMS team manages a section of the main IMS web page to include reports and documentation, as well as an area relating to application development. IMS Central is also a focus. Below are a few example resources:
- Sample report – IBM z/OS Connect and IMS Performance Evaluation
- Sample document – Application modernization with Java
- Application development – IMS GitHub (explore IMS sample code and tutorials for your IMS application development and deployment needs).
- IMS Central advocacy hub – Get access to IMS advocates and a wealth of advocacy resources on our platform, empowering advocates with insights, tools and inspiration.
The information above is a sample of what can be found on the main page in the resources category. There is also a section for education that includes an introductory video series and IMS courses on IMS Central. Also found are downloads including the IMS TM Resource Adapter, the IMS Enterprise Suite and IMS Universal Drivers. The downloads are available to IMS customers at no additional charge.
Another section of the main page is focused on IMS tools, which are products designed to enhance the performance and operation of IMS. There are currently more that 30 IMS Tools products that are categorized by function—for example, database reorganization, database administration, performance and problem management, and system and transaction management. IBM keeps the tools current as software within and outside of IMS changes. Some are packaged as Solution Packs to simplify ordering and pricing.
When you read through the main IMS web page and explore the reports and documentation shared, you quickly realize that IMS has a past and is fully participating in current programming initiatives. IMS has an important role with Cloud including Hybrid Cloud, Mobile and REST API (using z/OS Connect) and new tools and development approaches like DevOps.
What’s next?
In June, I will focus two articles on database technology on z/OS. I have already explored IMS DB, but Db2 has only had a passing glance.