IMS TM is a message-based transaction processor.

Definitions:

• A transaction is a specific set of input data that triggers the execution of a specific business application program (a process or job). The message that triggers the application program, and the return of any results, is considered one transaction.
• The word terminal is used throughout this information to describe devices and controllers. The operator terminals can be keyboard printers, display stations with keyboards, communication terminals, or a mixture of these devices.

IMS TM provides services to:

• Process input messages received from a variety of sources (such as the terminal network, other IMSs, and the Web).
• Process output messages created by application programs.
• Provide an underlying queueing mechanism for handling these messages.
• Provide high-volume, high-performance, high-capacity, low-cost transaction processing for both IMS DB's hierarchical databases and DB2's relational databases.

IMS TM supports many terminal sessions (on a wide variety of terminals and devices) at extremely high transaction volumes. The users of the terminal sessions can be:

• People at terminals or workstations.
• Other application programs, either on the same z/OS system, on other z/OS systems, or on non-z/OS platforms.

When IMS TM is used in conjunction with a database manager, IMS TM extends the facilities of the database manager to the online, real-time environment. IMS TM enables terminals, other devices, subsystems to enter transactions that initiate application programs, which access IMS DB or DB2 databases and return results.

You can define a variety of online processing options. 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 enables you to develop a wide range of high-volume, rapid-response applications, and to geographically disperse your data processing locations while keeping centralized control of your database.