Objects of Desire posting (long)

[Mark Merkow <mmerkow -at- ASU -dot- EDU>]

A couple of people on the list have expressed an interest in seeing m=
y=20
article on Object Oriented Technology, so here it is.

I hope you all enjoy it !

------------------------------------------------------

Objects of Desire
A Primer on Object Oriented Technology
By: Mark S. Merkow, CCP


=09These days it=B9s nearly impossible to pick up any technology-rela=
ted=20
book or journal and miss seeing extensive coverage of Object-Oriented=
=20
Technology (OOT).  We=B9ve become inundated with ads and articles for=
=20
products claiming to be object-this or object-that, when, in reality,=
=20
Object-Orientation is meaningful only when it=B9s used in the context=
 of=20
software development techniques.
=09It would be a real tragedy if the hype surrounding Object-Orientat=
ion=20
relegates it to just-another 90=B9s buzzword or technology du-jour, w=
hen=20
in fact, it=B9s the most promising software development approach to c=
ome=20
around in 20 years. =20
=09The value and appeal of Object-Orientation rests in its ability to=
=20
model a system and in its reusability.  However, mysteries present=
=20
barriers to acceptance by both seasoned computing professionals and=
=20
non-technical business managers and users. =20
Object-Orientation represents a radical departure from traditional=
=20
software development techniques.  Traditional software development=
=20
techniques create a representation of the functions within a process.=
 =20
Development occurs in phases =AD from analysis through design to=20
implementation, and separate sets of tools are needed for each phase.
Using Object-Orientation, a designer creates a library of objects=
=20
consisting of the behaviors (what an object does) and associated=20
attributes (what an object knows). These objects may be used over and=
=20
over without changes, and a common set of notation and tools can be=
=20
used throughout all phases of development.
Once the bulk of business systems are implemented using=20
Object-Oriented approaches, the process of software development=20
becomes a matter of reassembling components into new structures that=
=20
provide new services that can, in turn, be reused later.
=09Using traditional approaches to systems development, this feat cou=
ld=20
never be accomplished. Data may be accessed by any function that need=
s=20
it, so all functions must know precisely how the data is organized an=
d=20
how to navigate through it.  If data structures change, each and ever=
y=20
function that acts upon that data must be modified accordingly.
=09Under an Object-Oriented approach, shared public data areas are=
=20
eliminated.  Objects communicate through message passing mechanisms=
=20
rather than sharing common variables. =20
An object is a package of all of the functions necessary to maintain=
=20
data, along with an interface to handle messages from other objects.=
=20
How an object performs its functions is irrelevant to other objects.=
=20
If, In fact, the method of performing a function changes, no other=
=20
object will even realize that it changed since the interface remains=
=20
consistent.  In this way, changes that would otherwise affect many=
=20
parts of a traditionally developed system are localized into a single=
=20
point when Object-Oriented techniques are used.

Object-Oriented Modeling
=09The Object-Oriented approach uses the same organizational model th=
at=20
humans naturally use to manage complexity.  This model consists of =
=20
three methods of thinking:
=09=80 Differentiation of experience into particular objects and thei=
r=20
attributes.  For example, when people distinguish between a tree and=
=20
its size or proximity to other objects;
=09=80 Distinction between whole parts and component parts.  For =
=09=09  =20
example, contrasting a tree with its branches, leaves, and buds;
=09=80 Formation of and distinction between classes of objects.For =
=09=09  =20
example, distinguishing a class of trees from a class of rocks.

Because Object-Oriented technology mimics human language and thought=
=20
processes, it removes the burden of technical jargon.  A non-technica=
l=20
person could look at an Object-Oriented model and immediately see=
=20
what=B9s happening.  The trick is to view how a process operates base=
d=20
upon the viewpoints of the affected components, rather than by=20
defining what functions are necessary to create an artificial=20
representation of what occurs within the system.

Management Implications of Object-Oriented Approaches
=09Because an Object-Oriented approach presents a radical shift from=
=20
traditional methods, several management concerns are raised. =20
Traditional development efforts progress through each phase (analysis=
,=20
design, coding, testing, etc.) without reverting back to previously=
=20
completed phases.  This model, however, does not work well with=20
Object-Oriented techniques.  Management should relax rigorous=20
scheduling demands in favor of a reiterative development approach to=
=20
fully realize the potential of reusability.
=09New roles in developer teams must also be created.  An Object Ment=
or=20
is needed to ensure consistent use of the methodology and to help=
=20
developers work through problems.  There=B9s also a need for a Class=
=20
Librarian who is able to determine which previously built components=
=20
are suitable for reuse, as well as to maintain object integrity.
=09Perhaps the key element in adopting an Object-Oriented approach is=
=20
allowing employees adequate time and resources to learn the=20
techniques, as well as encouraging them to try new ways without=20
threatening their positions or their futures.

Trends in Object-Orientation
=09Computer industry forces are legitimizing and proliferating=20
Object-Oriented techniques.  IBM recently announced a framework for=
=20
using Object-Oriented technology within the entire line of IBM=20
systems, from mainframes to microcomputers.  Next Corporation=B9s=
=20
NEXTStep, Microsoft Corporation=B9s Cairo version of Windows, and=
=20
Taligent Corporation=B9s PINK operating system are beginning to show =
up=20
in more and more computers and provide rich sets of tools to develop=
=20
new applications through reusable class libraries of common system=
=20
components.  Integrated developer tools are also showing up regularly=
,=20
along with promises of reducing development effort by orders of=20
magnitude.  As the Object-Oriented Data Base Management Systems=20
(OODBMS) market continues to mature and industry-wide standards are=
=20
developed, the rapid proliferation of new applications is certain to=
=20
follow.
=09Object-orientation is becoming the norm in software development, a=
nd=20
managers and professionals in America=B9s corporations need a basic=
=20
understanding of it.  As Hugo once said, =B3There=B9s one thing stron=
ger=20
than all the armies in the world, and that is an idea whose time has=
=20
come.=B2

Copyright 1994
Mark S. Merkow, CCP

Printed in October 1994
The Computer Journal
Cheryl Cooper, Editor