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Screen Control Application Development System(SCADS)

Introduction

SCADS or Screen Control Application Development System is a collection of macros, externals, and utilities that comprise a comprehensive systems development toolset.

SCADS generates menu-driven applications which employ screen-controlled data entry. Applications developed with SCADS are well documented and structured, and thus are readily understandable and easily maintained.

SCADS is not an end user facility; it is intended for programmer/analysts as a development toolset. Use of the facility removes the burden of the mundane and often repetitive coding involved in screen formatting and input data editing. SCADS also provides a structured framework for application development. The system developer is more able to concentrate on the organization of the application and data base management.

SCADS consists of BASIC macros; consequently, it is very flexible and adaptable to unusual requirements. Its facilities are designed to address three common data processing functions: data entry, record inquiry, and reporting.

Data Entry and Record Inquiry:

Although none of the features of SCADS are workstationl dependent, the facility simulates a full screen smart terminal. Many of the best features of the full screen approach are incorporated. The terminal screen is divided into heading, body, and control sections. The heading section provides for plug-in variables for system title, menu, or screen title and record identification. The body of the screen contains menus or formatted data entry or inquiry windows. The control section at the bottom of the screen is reserved for a data entry mask, input area, and error and control messages. In keeping with SCADS screen oriented nature, control characters and/or program function keys provide the capability to move around the screen in a controlled fashion. Subscreen displays, logical windowing and process transfer functions are supported.

The generation of menus, screens, simple edit rules, and clerk control records is accomplished outside of the data entry or inquiry program using facilities that are themselves written in SCADS. Changes in any of these variables does not require recompiling the main data entry or inquiry program. Program hooks are available to accommodate special editing or screen handling and data base management.

The typical structure of a SCADS data entry program begins with initialization of application variables, opening of files, and building of the application's menus and screens. The mainline consists primarily of menu control code that invokes the SCADS menu and screen control macros.

Data base management is normally handled through hooks from SCADS macros by external procedures. This approach provides flexibility to the application developer and conserves storage space for the mainline program.

Reporting:

The UniVerse DBMS offers an excellent fourth generation language referred to as RETRIEVE. SCADS applications take advantage of the RETRIEVE reporting language for most reporting. The PROC processor is employed to provide most of the control framework for reporting. However, there are three important areas in which SCADS is utilized to support the reporting function.

The menu and clerk control capabilities are used to control clerk access to the main menu of reporting applications. Secondly, a utility has been developed in SCADS to interactively prompt for record selection criteria. This facility provides the ability for end user staff to specify modifications to the selection specifications of canned reports without the onus of using the editor or knowing the technical syntax of the fourth generation language or the PROC processor. A third SCADS developed facility, QUIKREP,  provides the capability for end users to define complete report specifications in the same manner as the more limited specification of selection criteria. The report specification facility, while insulating the user from syntax problems, does require understanding of reporting concepts and an understanding of the target data base.

SCADS Macros, Externals, and Utilities

A SCADS application makes use of several types of program code: macros, which are modular portions of code designed to be included and compiled within a program ; externals, which are complete external subroutines; and utilities, which are complete applications.

Macros

Macros are programmed routines which have been designed to perform specific functions. They reduce the amount of redundant code, increase the reliability of code, reduce the development time and help to document and structure an application, thereby making the application readable and maintainable.

There are essentially 4 type of SCADS macros employed within a SCADS program:

- File opening macros

- General, unnumbered macros

- 9000 series SCADS macros

- 8000 series SCADS macros requiring or allowing program hooks

The macros are designed to work in combination with each other within a program.

The SCADS opening, general and 9000 macros are contained in the MACRO.LIB file, which is common to all SCADS applications. The 8000 series macros are placed in an application specific library.

Externals

The SCADS externals are compiled BASIC external subroutines. Some are used by the SCADS macros, while others are common facilities available to programmers for inclusion in applications.

Externals are found in the APPL.PGM file, which is available to all SCADS applications.

Utilities

The utilities provided with SCADS are SCADS applications in and of themselves. They are designed to create or maintain features of new or existing SCADS programs. The SCADS utilities are:

DMU Dictionary Maintenance Utility