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Dynamic Translation of Object-Oriented Notification between Objects

IP.com Disclosure Number: IPCOM000113774D
Original Publication Date: 1994-Oct-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Chow, AC: AUTHOR

Abstract

A notification machanism is sometimes called callback mechanism in procedural programming environment. It is used for an object to notify other objects about its state change. Objects are always treated as components or building blocks for other higher level composite components just like subroutine reuse in procedural language. However, once a subcomponent is grouped into a bigger composite component, Its notification is limited to the scope of the composite component itself unless the subcomponent can be exposed at the composite component level. But, the encapsulation of the composite component is broken in such cases. Or, programmer can hardcode the callback routine and translate the sub-notification to the composite notification by hand.

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Dynamic Translation of Object-Oriented Notification between Objects

      A notification machanism is sometimes called callback mechanism
in procedural programming environment.  It is used for an object to
notify other objects about its state change.  Objects are always
treated as components or building blocks for other higher level
composite components just like subroutine reuse in procedural
language.  However, once a subcomponent is grouped into a bigger
composite component, Its notification is limited to the scope of the
composite component itself unless the subcomponent can be exposed at
the composite component level.  But, the encapsulation of the
composite component is broken in such cases.  Or, programmer can
hardcode the callback routine and translate the sub-notification to
the composite notification by hand.

      This solution provides a generic translation of the
notification mechanism between a composite component and its
subcomponents in order to encapsulate a composite component cleanly
without hardcoding.  Each subcomponent has a notification table that
keeps all the objects to be notified.  A composite object has a
generic method (Callback Routine) that can be placed on the
notification table of the subcomponent.  A notification tag is also
associated with the callback routine.  When a subcomponent notifies
the composite component via its callback method, the callback method
uses the information in the tag to translate the sub-notificatio...