The SDF-P software product is a procedure language that extends the BS2000 command language to a programming language in which structured programming can be performed just as it is using high-level programming languages. With SDF-P, even a beginner can generate short procedures quickly and easily. In addition, the creation and maintenance of large and complex procedures are also greatly simplified. Finally, it is possible, by assigning structured variable streams (referred to briefly as S-variable streams) to store structured outputs in variables, which can then be further processed in numerous ways: e.g. they can be diverted to graphical user interfaces.
Procedures which are created in accordance with the rules of SDF-P are called structured procedures or S procedures. (Procedures which are not created in accordance with the SDF-P rules are called non-S procedures.)
On the command level, SDF-P supports functions of high-level programming languages.
As delivered, SDF-P includes a number of predefined (or built-in) functions with which, amongst other things, variables can be processed and converted or environmental information such as the job status, the processor name or the current date can be determined. These functions can be used in procedures in the same way as the functions of high-level programming languages are used in programs.
In BS2000, SDF-P offers a variable concept of the type that is familiar from high-level programming languages. Thus, it supports not only simple variables, but also complex variables. Variables in SDF-P are also characterized by their data type and their life span or visibility. SDF-P permits the processing of variables both at the command interface and the program interface.
As in high-level programming languages, procedure execution is controlled by loops and branches implemented by means of SDF-P commands. The names selected for these commands are those that are already familiar from various programming languages: WHILE, FOR, REPEAT, IF, ELSE.
SDF-P is a block-oriented programming language, i.e. an essential characteristic of procedures under SDF-P is their structuring in command blocks. These command blocks are not only formed from loops and branches; the programmer can also define any associated procedure parts as command blocks.
The advantages of working with command blocks are, firstly, that the organization of the procedure structure is easily understood and, secondly, error handling is also blockoriented, meaning it can be applied to defined procedure parts.
Product structure
The entire functionality of SDF-P is implemented in two subsystems: SDF-P and SDFPBASY (selectable unit SDF-P-BASYS). While the SDF-P subsystem is chargeable, the SDF-P-BASYS subsystem is included in the BS2000 basic configuration. Procedures offering the SDF-P functionality can be executed subject to the following conditions:
The SDF-P subsystem must be installed and loaded.
The SDF-P subsystem is not installed but the procedures are available in a (compiled) intermediate format created on a system where SDF-P was installed.
A system where SDF-P is not installed permits syntax checks to be performed on S procedures, with the exception of control flow commands and the COMPILE-PROCEDURE command. However, attempts to execute procedures which include chargeable functions will be rejected unless the procedures exist in compiled format.The commands and functions of the SDF-P-BASYS subsystem are also described in the manual “Commands” [3].
A description of dependencies between SDF-P and SDF-P-BASYS versions is given in section “Software configuration”.
Target group
This manual is intended both for BS2000 users who generate procedures as a way of making their everyday work easier and for programmers or system administrators who, for example, perform their system administration tasks with the aid of complex procedures.
Since creating SDF-P procedures is similar to writing procedures in high-level programming languages, the originator of the procedure is generally called a programmer.