Title: Challenges with Object-Oriented Frameworks
and a Solution Using the APPC Pattern
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Prof. Dr. Karl Lieberherr
College of Computer Science
Northeastern University
Boston, Massachusetts
www.ccs.neu.edu/home/lieber

January 1999

Abstract:
Object-oriented frameworks are widely used as encapsulations of 
behavior for various application domains. 
When multiple frameworks are used and composed, several challenges arise
as described by Riehle and Gross (OOPSLA '98): 
complexity of classes and object collaborations, code tangling and
proper separation of concerns, and achieving reusable models.

We present an architectural pattern, called the APPC pattern (Adaptive
Plug-and-Play Component pattern), to help
address those challenges.
The APPC pattern builds on the observation that the
general unit of reuse is not a single class, but a slice of behavior 
affecting a set of collaborating classes. 

The APPC pattern uses an "ideal" UML class diagram to express 
class collaborations using any object-oriented
programming style but preferably using the traversal/visitor style.
The mapping of the "ideal" UML class diagram into a concrete UML
class diagram is achieved using any
object-oriented programming style but preferably
using the traversal/visitor style.
The talk will outline how the APPC pattern can be implemented in Java
using a traversal package and Java Beans.

The APPC pattern not only facilitates the construction of 
complex software, specifically banking applications,
by making the collaborations explicit,
but it does so in a manner that supports the evolutionary 
nature of both structure and behavior.