As an alternative to specifying screen layouts dynamically, the
INPUT statement offers
the possibility to use predefined map layouts which makes use of the Natural
object type map.
This document covers the following topics:
Using predefined map layouts rather than dynamic screen-layout specifications offers various advantages such as:
Clearly structured applications as a result of a consequent separation of program logic and display logic.
Map layout modifications possible without making changes to the main programs.
The language of an applications's user interface can be easily adapted for internationalization or localization.
The benefit of using objects such as maps will become obvious when it comes to maintaining existing Natural applications.
Maps (screen layouts) are those parts of an application which the users see on their screens.
The following types of maps exist:
Input Map
The dialog with the user is carried out via input maps.
Output Map
If an application produces any output report, this report can be
displayed on the screen by using an output map.
Help Map
Help maps are, in principle, like any other maps, but when they are
assigned as help, additional checks are performed to ensure their usability for
help purpose.
The object type "map" comprises
the map body which defines the screen layout and
an associated parameter data area (PDA) which, as a sort of interface, contains data definitions such as name, format, length of each field presented on a specific map.
Related Topics:
For information on selection boxes that can be attached to input
fields, see SB - Selection
Box in the INPUT statement documentation and
SB - Selection
Box in the Parameter Reference.
For information on split screen maps where the upper portion may be
used as an output map and the lower portion as an input map, see
Split-Screen
Feature in the INPUT statement
documentation.
Maps and help map layouts are created and edited in the map editor.
The map editor is used to create character-based user interfaces. If you want to create complex graphical user interfaces, you will use Ajax Developer instead. Ajax Developer includes a number of tools. Its central tool is the Layout Painter which is used to define layouts for HTML pages. The appropriate local data area (LDA) is created and maintained in the source editor.
For information on input processing using screen layouts specified
dynamically, see Syntax 1 - Dynamic
Screen Layout Specification in the INPUT
statement documentation.
For information on input processing using a map layout created with
the map editor, see Syntax 2 - Using
Predefined Map Layout in the INPUT statement
documentation.
An input map is invoked with an
INPUT USING MAP
statement.
An output map is invoked with a
WRITE USING
MAP statement.
Processing of a map can be stopped with an
ESCAPE
ROUTINE statement in a processing rule.