Introduction
IBM Data Virtualization Manager for z/OS (DVM) provides seamless, real-time controlled access to IBM Information Management System (IMS) database data. It allows ODBC, JDBC, DVM client, and web clients to access IMS database data as a relational model by using simple SQL-based queries. It can be used with traditional client/server applications, desktop productivity tools that use ODBC, JDBC, and two-tier and three-tier web implementations.
Using the DVM studio, you create the server metadata that provides the information necessary to virtualize your IMS data. This metadata includes virtual source libraries, virtual tables, virtual collections, and virtual views. Before creating a virtual table to access data in an IMS database, you must import the Program Specification Block (PSB) and Database Definition (DBD) source members, and the copybooks that describe the layout of each IMS segment into one or more virtual source libraries defined to the server. In each case, specifying the external Partitioned Data Set (PDS) / Partitioned Data Set Extended (PDSE) that contains the information specific to the type of source library.
The IMS catalog
The IMS catalog is an optional system database, available since IMS version 12, that contains trusted metadata and definitions of the IMS databases and application program views that are defined to IMS. Each database and application program view that is defined to IMS is stored in a separate record in the IMS catalog, which is fully managed by IMS and allows IMS to participate in solutions that require the exchange of metadata.
Using the IMS catalog makes it possible to stop using and maintaining external PDS/PDSE containing source DBD, PSB or copybook members relating to you IMS data. When the metadata is updated, the catalog is also updated to reflect the change. The data is thus current because the consumers get metadata dynamically from the active IMS catalog rather than from external PDS/PDSE files maintained separately. The catalog also includes a versioning system. This system allows the current version of the metadata, and a user-specified number of previous versions, to be kept and available for the applications.
With the IMS catalog you can use SQL DDL statements to change DBDs, PSBs, and Application Control Blocks (ACBs) with IMS automatically updating the catalog, and, if enabled, automatically activating certain changes to database or program view definitions.
Support for the IMS catalog in DVM
In December 2022, IBM Data Virtualization Manager for z/OS was enhanced to allow the DVM studio to support extracting IMS DBD and PSB sources from the IMS catalog database as an alternative to the pre-existing process of DBD and PSB sources being extracted from external source libraries.
The two short videos below show how to use the new DVM IMS catalog support to quickly extract a DBD and PSB in the IMS Catalog to create DVM IMS metadata maps that can be used to create a DVM virtual table to access IMS data.
Extracting a DBD
Extracting a PSB
More details can be found in the IBM Documentation Centre by clicking this link => IBM Data Virtualization Manager for z/OS Users Guide
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