Rational Developer for System z, Version 7.6

Screen

A Screen belongs to a Dialog and is considered as a list of fields.

A Screen is constituted of:

These fields can be grouped into categories (top, bottom, repetitive). The processing is executed category by category.

The Presentation and Display default options defined in the Dialog Definition may be modified at the Screen level.

The default options of the Screen itself become the default options of the fields which make up a Screen. Each field is characterized by:

These presentation options can be changed in each call of Data Element on the Screen.

The elements called in the Screen are used to build the Screen layout and determine the processing of the Screen data.

The processing of the data external to the Screen is determined by the call of Segments and, for each of them, by the specification of its physical characteristics (type of organization...) and type of use (read, update...). You can indicate additional processing via specific code.

Generation

The development of a Dialog/Screen is independent of the environment. This allows the generated online application to be portable.

After describing and defining a Dialog and its constituting Screens, you can generate them. This will automatically produce the following elemnts:
  • SCREEN MAPS

    The physical Description of the generated Screen is internal to the program for a number of environments and is external for others. The code to generate, which can either be in native mode or in a more evolved language (BMS for IBM-CICS, MFS for IBM-IMS, FORMS for Bull...).

  • 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 associated with a given Screen is generated in a single program which applies to this Screen only.
    This basic principle ('one Program for one Screen') 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.
    The generated online program allows man/machine exchanges in a pseudo-conversational mode in such a way as to optimize computer usage without penalizing the end-user.

    A number of the generated processings are implicitly generated from the Screen Description. These are the technical processings (reception, formulation and display of messages, initialization of fields) as well as the processings generated from the detailed analysis of an online program (validations and updates, data access).

    A number of options taken into account at generation time (external names of standard files, terminals used, etc) can be modified in the -GG Lines section of the -G Lines tab.

    Finally, the processings that are specific to a given Screen, described in specific code, complete the standard processings in order to obtain the complete generation of an online program.

  • SCREEN FLOW

    The Screen flow is the part of the Screen Description which 'animates' a Dialog, the sequence of the Screens defined and analyzed and which ensures the branching of the different Screens according to various scenarii.

    Screen branching is performed via reserved Data Elements PFKEYs or characters, depending on the environment.

    Depending on the environment, the Dialog can be generated:
    • Either in one single Monitor program which is called by each online program during the dispatching phase (example: IMS),
    • Or in each of the online program (example: CICS).

For explanations on the generated Screen, refer to the On-Line Systems Development manual which you can find at the following URL:

http://www-01.ibm.com/support/docview.wss?rs=37&uid=swg27005477


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