Browse Prior Art Database

Heterogeneous Object Model-View Relationships

IP.com Disclosure Number: IPCOM000102456D
Original Publication Date: 1990-Nov-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 2 page(s) / 114K

Publishing Venue

IBM

Related People

Griffin, SF: AUTHOR

Abstract

This article describes a method for extending the facilities of the object dependency management protocol in the Smalltalk/V Presentation Manager* environment to allow independent non-Smalltalk Presentation Manager applications to participate in object dependency relationships. Object-oriented development platforms based on Smalltalk describe a protocol for managing dependencies between related objects. These protocols allow an object to "register interest" in other objects and receive notification and information when the object in which they have registered interest changes. However, these protocols can only be used by the objects created in the Smalltalk environment.

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Heterogeneous Object Model-View Relationships

       This article describes a method for extending the
facilities of the object dependency management protocol in the
Smalltalk/V Presentation Manager* environment to allow independent
non-Smalltalk Presentation Manager applications to participate in
object dependency relationships. Object-oriented development
platforms based on Smalltalk describe a protocol for managing
dependencies between related objects.  These protocols allow an
object to "register interest" in other objects and receive
notification and information when the object in which they have
registered interest changes.  However, these protocols can only be
used by the objects created in the Smalltalk environment. Other
programs which may run on the same operating system, but outside the
realm of the Smalltalk platform, cannot participate in this
dependency management scheme.

      The Smalltalk environment currently defines an object
relationship wherein one data object, called a "model" is represented
to the user by another object, called a "view." Models implement the
data manipulation portion of an application, while the view presents
the model visually.  In many cases, a model may have multiple views
which depict different aspects of the data.  In order to ensure that
views are appropriately updated when data changes, an object
dependency protocol is provided to allow views to register interest
in a particular model.  As the model's data or behavior changes, it
informs the views so that the current state of the program may be
represented to the user. This protocol is specific to the Smalltalk
platform, requiring that the model and view are homogenous to the
extent that they are created on the same platform.

      This invention utilizes the existing object dependency
protocol, as well as the "delegate object model" used in distributed
Smalltalk systems, to allow non-Smalltalk Presentation Manager
programs to establish dependencies on Smalltalk objects, and vice
versa.  Using this design, the model-view paradigm is extended to
allow heterogeneous objects (non-Smalltalk programs/data and
Smalltalk objects) to participate in the dependency relationship. The
technique extends the model- view paradigm to heterogeneous objects
by creating Smalltalk "delegate" objects which act as the
non-Smalltalk object and communicate to the object they represent
using the OS/2* Presentation Manager Dynamic Data Exchange (DDE)
protocol. When a non-Smalltalk program wishes to register interest in
a Smalltalk object, it initiates a DDE conversation using standard
OS/2 Presentation Manager APIs and messages.  The external object may
then communicate indirectly with Smalltalk objects provided that two
extensions are made to the Smalltalk environment:

      1.  An exte...