Chapter 12. Overview of the IMS Transaction Manager


IMS Transaction Manager (IMS TM) performs online transaction processing, which, in its simplest form, comprises the following steps:

1.

Receiving a request for work to be done. The request is entered at a remote terminal and is usually made up of a transaction code, which identifies to IMS the type of work to be done, and data, which is used in performing the work.

2.

Initiating and controlling a specific program that uses the data in the request to complete the work that the remote operator requested, and to prepare data for the remote operator in response to the request for work (for example, an acknowledgment of work done or an answer to a query).

3.

Transmitting the data prepared by the program back to the terminal that originally requested the work.

IMS TM also provides solutions for cooperative processing, distributed database processing, and continuous operation, such as:

  • Providing a high-performance transaction processing environment for database management systems, such as IMS Database Manager (IMS DB) and DB2 UDB for z/OS.

  • Enhancing system management.

  • Simplifying network administration.

  • Managing and securing the IMS TM terminal network.

  • Routing messages from terminal to terminal, from application to application, and between application programs and terminals.

  • Queuing input and output messages, and scheduling transactions by associating programs with the messages.

  • Participating in distributive processing scenarios where other programs, such as IBM WebSphere Studio Application Developer Integration Edition, need to access IMS.

Definition:

A logical unit is an addressable resource that can be an application program, a terminal, or a subsystem, such as CICS. A logical unit can also be a component of a general-purpose terminal system that consists of a programmable controller and its attached operator terminals, printers, and auxiliary control units.


Terminals or logical units can also be thought of as ports or windows through which a business gives a user access to the network and its functions. In times past, the port was a physical device (for example, a 3270 terminalnot an emulation program). Today, the port is more likely to be an application program that implements an installation's business rules.

In This Chapter:

  • "IMS TM Control Region"

  • "IMS TM Messages" on page 171

  • "IMS Transaction Flow" on page 173

  • "IMS TM Network Overview" on page 175

  • "The Data Communication Control (DCCTL) Environment" on page 189

  • "Operating an IMS Network" on page 190



Introduction to IMS. Your Complete Guide to IBM's Information Management System
An Introduction to IMS: Your Complete Guide to IBMs Information Management System
ISBN: 0131856715
EAN: 2147483647
Year: 2003
Pages: 226

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