A Screen belongs to a Dialog and is considered as a list
of fields.
A Screen consists of the following elements:
- Defined Data Elements,
- Specific labels of the Screen,
- Calls to other Screens.
These fields can be grouped into categories (top, bottom, repetitive).
Categories are processed one after the other.
The presentation and display default options that are defined in
the Dialog Definition can be modified at the
Screen level.
The default options of the Screen itself become the default options
of the fields that constitute the Screen. Each field has the following
characteristics:
- A position (relative or absolute),
- A label (for the Data Elements),
- Presentation characteristics,
- Display characteristics.
These presentation options can be changed in each Data Element
call in the Screen.
The elements that are called in the Screen build the Screen layout
and determine the processing of the Screen data.
The elements that are external to the Screen are processed through
Segment calls. Their physical characteristics (such as the type of
organization) and type of use (such as read or update) must be specified.
You can indicate additional processing with specific code.
Generation
The specification of a Dialog
or Screen is independent of the environment. The generated code is
then portable.
After defining and describing a Dialog and its
constituting Screens, you can generate them. The generation automatically
produces the following elements:
- Screen maps:
The physical description of the generated Screen
is internal or external to the program, depending on the environment.
The code to generate, which can be in native mode or in a more evolved
language (BMS for IBM CICS for example).
- Online programs:
An online program is the sequence of the following
processing:
- Message reception,
- Validation processing,
- Processing of received information,
- Output formatting,
- Display.
All the processing of a Screen is generated in a single program
that applies to this Screen only.
This basic principle has many
advantages:
- The program is independent of the structure and content of the
Dialog,
- The size of the online programs is homogeneous,
- The maintenance and implementation are easy.
Part of the generated processing is implicitly generated
from the Screen description:
- The technical processing (reception, formulation, and display
of messages, initialization of fields)
- The processing that is generated from the detailed analysis of
an online program (validations and updates, data access)
Some generation options can be modified in the -GG
Lines section of the -G Lines tab.
- Screen Flow:
The screen flow is the part of the Screen description
that animates a Dialog. It branches to the different Screens according
to various scenarios.
Screen branching is ensured through special
fields (function keys or other characters) depending on the environment.
Depending
on the environment, two types of generations are possible for a Dialog:
- Centralized generation in a single monitor program that is called
by each online program during the dispatching phase (example: IMS),
- Distributed generation in each of the online program (example:
CICS).
Note: For the instances that are
imported from Pacbase, the skeleton language of the local generation
is identical to the Pacbase skeleton language. This piece of information
is retrieved from the extraction of the Pacbase models and from the
import. It is stored in the Library.
For
explanations on the contents of the generated code, see the COBOL description of a generated Screen.