With the adapter installed, you use the FOCUS language to request access to IMS databases. There is no need for specialized subroutines or embedded commands.

In IMS, each view of a physical or logical database is represented by a PCB (Program Communications Block). A PSB (Program Specification Block) is a collection of PCBs. It controls access to databases and views. FOCUS, like any other application, must access IMS data through PCBs in a PSB:

• To make a view intelligible to FOCUS, you create a Master File that describes it in FOCUS terminology. This Master File makes it possible to refer to the individual fields of the IMS databaseusing the FOCUS field name or the IMS field name.
• To inform FOCUS of which PCBs are included in a particular PSB, and to associate a Master File with each PCB in the PSB, create a FOCPSB. In the DBCTL environment, you can create an Access File instead of a FOCPSB.

In fact, once you have Master Files and FOCPSBs or Access Files that describe IMS databases and PSBs, you can use all FOCUS reporting facilities to access the data. You can also use the FOCUS Dialogue Manager facility to create prompt-driven procedures for reporting from IMS databases. There is no need to use conventional computer languages such as COBOL.

Database administrators (DBAs) or application developers often create Master Files and FOCPSBs. Therefore, they may already be available at your site.

If you need to create a Master File and your site has a COBOL copy book that describes the IMS data, you may be able to use the COBOL FD Translator to help create the Master File. For more information, consult your FOCUS COBOL FD Translator documentation.