Introduction to Data Management

Developing Applications With PATHMAKER
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When it is first presented, the default screen contains the title, the function key
assignments, the fields that you have specified as part of the requester context, the
headings for those fields, and the video attributes. You can use the Screen Painter to
move data fields to different locations on the screen and to add decorations made up
of unchanging text characters that you enter from your keyboard. These decorations
can include field labels, explanatory text, and borders surrounding different areas on
the screen. They can greatly improve the screen’s readability.
After modification by the Screen Painter, an application screen might appear as shown
in Figure 5-6. On this screen, all data input fields (such as FIRST-NAME, LAST-
NAME, and STREET) and one data output field (ORDER-REFERENCE) appear as
solid underlines. The UNIT-PRICE and TOTAL-PRICE data output fields appear as
reverse video blocks. All other elements on this screen, such as field labels and
directions for the end user, are decorations.
If you have specified only the screen title and function key assignments but have not
used NonStop SQL or DDL to specify your data fields, the requester screen will
contain only the title and key assignments. In this case, you are basically working
with a blank screen. You can use decorations to approximate the positions of the data
fields. After defining these fields with NonStop SQL or DDL, you can use the Screen
Painter to replace the corresponding decorations with the actual fields.
Using the Screen Painter is a task you can perform at any time before you actually
generate the requester. The work that you accomplish with the Screen Painter is
generated by PATHMAKER as part of your SCREEN COBOL requester code.
Simulating the Application. After you create your preliminary screen and refine it as you
wish, you must suspend work on the requester until you generate the application
services. At any point after you create the default screen, however, you have a
prototype requester whose operation you can simulate for the end users. To do this,
you simply select the simulation function from the main menu and then step through
the application by using the function keys that you have defined for screen
navigation. You can conduct this simulation even if you have not yet defined the data
fields with NonStop SQL or DDL. Although you can demonstrate the appearance of
your application, you cannot process data.
Defining the Services
A service, as noted earlier, is one module of a complete server program. A service
accepts a specific type of request and performs the particular database activity that
corresponds to that request. For example, within the same server, you might want
one service that adds order records to an order file, another that modifies records in a
parts file, and a third that checks records in a customer file.