Browse Prior Art Database

Model View Schema

IP.com Disclosure Number: IPCOM000121978D
Original Publication Date: 1991-Oct-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 2 page(s) / 99K

Publishing Venue

IBM

Related People

Baker, R: AUTHOR [+3]

Abstract

The introduction of object-oriented programming technology into the application software development field requires that methodologies for object-oriented design be established. In order to benefit from the usability of the software classes, a design framework which outlines the rules and relationships between classes must be developed. Such a framework alleviates inconsistencies in interfaces (such as error handling, argument validation, control and communication) when integrating sets of classes built by different developers.

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This is the abbreviated version, containing approximately 51% of the total text.

Model View Schema

      The introduction of object-oriented programming
technology into the application software development field requires
that methodologies for object-oriented design be established. In
order to benefit from the usability of the software classes, a design
framework which outlines the rules and relationships between classes
must be developed. Such a framework alleviates inconsistencies in
interfaces (such as error handling, argument validation, control and
communication) when integrating sets of classes built by different
developers.

      Provided here is a design schema for object-oriented class
hierarchies which will facilitate hardware platform-independence in
object-oriented software systems and allow considerable flexibility
in developing the end user interface (EUI) for application software.
This schema overcomes the current difficulties in writing
applications for multiple platforms and display systems (windowed and
non-windowed) by separating the EUI-specific behaviors of the objects
from the data itself, addressing the issues of distributed object
architectures and portability of code over various hardware and
software platforms.

      The Model View schema is a design concept which is
characterized by the desire to separate the viewing portion of an
application from its functionality and to support multiple views of
an object concurrently. Smalltalk (originating from Xerox PARC) first
introduced an object-oriented programming environment which utilizes
the concept of 'Model-View-Controller'. The design provided here is
an improvement of that concept.

      The Model View schema involves separating the data-dependent
part of an application (the model) from its visual representation. In
a simple example of a counter, there could be several views of a
counter to the end user - a bar chart, a digital LED (light-emitting
diode) and a gauge. These are views of the data and are independent
of the data itself but merely reflect the current state of the model
object, i.e., the counter. The counter model is responsible for
incrementing and decrementing its internal data, the value that is
displayed. It sends 'update' messages when its value changes to any
kind of object that depends on it. Thus, multiple views of an object
can be updated simultaneously.

      Between the model and the view in the Model View schema is an
object called the Event Interface. This object localizes the
contracts betwee...