gtpa2m0fApplication Programming

High Performance Option

If your TPF system includes the High Performance Option (HPO) licensed feature, it is important that you have a basic understanding of its terminology and functions. You must consider certain coding issues if you are writing application programs for an HPO system. You can find additional overview information about the High Performance Option feature in the TPF General Information and TPF Main Supervisor Reference.

An installation can have several TPF systems. If these systems function completely independently of one another, each must maintain its own database of application programs and program data. The High Performance Option feature allows these TPF systems to be interconnected so that any system can access the applications and data of some or all of the others. The shared access means that data need not be replicated from system to system.

The High Performance Option feature comprises the following 2 components that can be installed separately:

Combined, these components allow interconnection of TPF systems, an important capability when multiple TPF systems are required to handle high-volume business. This interconnection can be effective only if shared data is always as current as possible, which has critical implications in the writing of application programs. Later sections describe these implications in detail.

One especially important aspect of the Multiple Data Base Function is the subsystem. Any TPF system running with MDBF can be divided into as many as 64 subsystems, each of which contains a complete and possibly distinct set of application programs and application data. One of the subsystems, the basic subsystem, contains the control program and system utilities for all the subsystems, and may contain basic subsystem application programs as well. Furthermore, any subsystem (including the basic subsystem) can be subdivided into as many as 128 subsystem users. (The total number of subsystems and subsystem users cannot exceed 128.) All subsystem users in a single subsystem share application programs and may or may not share data.