Using Logical Record Facility

Logical Record Facility is a runtime facility that allows application programmers to access CA IDMS data without having to know the physical structure of the database. Under LRF, programmers do not have to use database navigation statements to access information. This is because the DBA predefines database access logic that is typically coded by programmers.
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Logical Record Facility (LRF) is a runtime facility that allows application programmers to access CA IDMS data without having to know the physical structure of the database. Under LRF, programmers do not have to use database navigation statements to access information. This is because the DBA predefines database access logic that is typically coded by programmers.
LRF offers many advantages for the corporate information system:
  • Enhances runtime efficiency. Database access through LRF often requires less operating-system overhead than database access through navigational DML commands. LRF can save overhead by reducing the number of program calls.
    For batch programs running under the CA IDMS central version (CV), CA LRF can also minimize supervisor calls (SVCs). This results in faster and more efficient database access.
  • Allows for increased data integrity. With LRF, the DBA can write all database navigation instructions in the subschema. This helps to ensure that the logical relationships of the data are preserved.
  • Allows for data security. The DBA can use LRF to:
    • Restrict the records and fields viewed by the application program
    • Restrict the database record occurrences viewed by the application program
    • Restrict the operations that the application program can perform on records and fields
  • Provides a flexible way to present data to different application programs. With LRF, the DBA can use standard relational operations to:
    • Select the record occurrences that the program can access
    • Project the fields that appear in the program's view
    • Join together information from two or more database records
    • Compute new fields based on existing field values
    These relational operations let the DBA establish relationships that do not exist in the schema. They also let the DBA tailor logical views of data to individual programs. No matter how the DBA chooses to construct a view, the application program will see the data as a single table.
  • Simplifies a program's access to the database. LRF eliminates the need for programmers to learn the database structure. By using LRF, a programmer does not have to be familiar with database navigation techniques or keep track of database currency.
  • Facilitates program maintenance. Because LRF insulates application programs from the database, changes to the logical and physical database structures have minimal impact on existing programs. For example, the DBA can change selection criteria for a record, and the program need not be recompiled
  • Reduces programming redundancy. Because all database navigation instructions are placed in a path, the programmer does not have to code these instructions. Applications that require similar information can access the path rather than issue the database navigation statements themselves.
To use LRF successfully, you must understand your role as the DBA in defining logical-record subschemas. You must also understand how the applications programmer uses the subschemas that you define.