SU and the Host Language Interface (HLI)

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This chapter describes how to use the FOCUS Host Language Interface (HLI) to read and modify centrally controlled databases. (The FOCUS Host Language Interface enables programs written in COBOL, FORTRAN, PL/1, or Assembler to read and modify data in FOCUS files.) It describes how two or more users can use HLI in SU to read and modify the same database concurrently. Each user is unaware of other users and may retrieve, add, delete, or change data independently.

All programs address the same copy of HLI, which is executed by the FOCUS Database Server. When a program on a source machine issues a FOCUS call containing an HLI command, the FOCUS subroutine transmits the call to the copy of HLI on the server, which then executes the command. You do not need to change programs designed to run in local mode. However, you must insert certain parameters into the File Communication Block. For more information, see The File Communication Block (FCB).

This chapter assumes that you are already familiar with HLI.


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