This chapter describes:
The Micro Focus Dialog System provides for independence between screen and keyboard input/output (I/O), and a COBOL application program. In much the same way that a database management system (DBMS) provides for independence of the data from the application, Dialog System separates out the human interface. This means that the application program needs only to be concerned with basic data processing tasks, and thus becomes smaller, simpler and much easier to code and maintain. Dialog System consists of a definition component and a run-time component.
You can use the definition component to define panels, which are rectangular working areas on the screen where you can specify data fields and keystrokes. The interaction between the screen and the user, based on this definition of keystrokes associated with a panel, is known as a dialog . Panels, which can be up to 80 characters wide and 25 lines long, can be used individually to create layouts for simple data entry, or they can be used collectively to make screensets .
A screenset is a set of panels with their associated data fields and dialog for one application. You can design complex screensets, incorporating pulldown menus, popup windows, selection bars, scrolling groups, help screens, function key support, and data validations.
You can use the run-time component to run the screenset and dialog interactions without an application program; this enables you to test a screenset and its dialog without the application program that uses the screenset. The run-time component also supports the screenset when it is being used by a program. This is done by using a simple call interface between the program and the screenset through a control block and a Data Block.
Therefore, once a program is produced, you can make extensive changes to the screenset without actually changing the program.
This guide describes the Character Mode version of Dialog System. You can use this version to create character-based user interfaces for applications running in character environments. The alternative version, for Graphical Mode, enables you to create graphical user interfaces for applications to run in graphical environments such as Presentation Manager on OS/2 and Microsoft Windows.
The Character Mode version of Micro Focus Dialog System can be run on DOS, OS/2 or UNIX operating systems; moreover, screensets are transferable between UNIX and DOS environments. You can create screensets on a DOS machine that are usable on UNIX. These screensets can be modified on UNIX and then run on DOS, as your circumstances require.
Obviously, the differences in these two operating systems result in differences in the use of certain facilities, such as line drawing and character graphics. To avoid problems, use only standard ASCII characters (codes 032 through 127) in any text that you enter. See the chapter Panel Painting for more information. Other limitations are clearly identified in this guide.
The approach to programming using Dialog System is different to previous methods of programming. How much you change your own approach depends on a number of factors, including your own individual preferences.
The fundamental advantage of using Dialog System over your previous method of programming is that all keyboard and screen handling is removed from your program. Additionally, most of the data validation, menu control, scrolling lists and help screens are no longer handled by your program.
Instead, all of these functions are handled by the Dialog System, using a very simple call interface to the COBOL program through a control block and a Data Block.
The major steps in developing your application with Dialog System are:
This guide is designed for easy reading and subsequent reference.
Dialog System runs on DOS, OS/2 and UNIX environments. This guide contains information for running Dialog System on all of these environments, with differences being shown where they occur. Where information is shown separately for each of the environments, it is presented in the sequence DOS, then OS/2, then UNIX, with a note in the margin indicating the environment.
All references to DOS include DOS and OS/2 unless otherwise stated.
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