In review
Object-oriented analysis (OOA) is concerned with developing
software engineering requirements and specifications that expressed
as a system's object model (which is
composed of a population of interacting objects), as opposed to the
traditional data or functional views of systems. OOA can yield the
following benefits: maintainability
through simplified mapping to the real world, which provides for less
analysis effort, less complexity in system design, and easier
verification by the user; reusability
of the analysis artifacts which saves time and costs; and depending
on the analysis method and programming language,
productivity
gains through direct mapping to features of Object-Oriented
Programming Languages [Baudoin
96].
An object is a representation of a real-life
entity or abstraction. For example, objects
in a flight reservation system might include: an airplane, an airline
flight, an icon on a screen, or even a full screen with which a
travel agent interacts. OOA specifies the structure and the behavior
of the object- these comprise the requirements of that object.
Different types of models are required to specify the requirements of
the objects. The information or object model contains the definition
of objects in the system, which includes: the object name, the object
attributes, and object relationships to other objects. The behavior
or state model describes the behavior of the objects in terms of the
states the object exists in, the transitions allowed between objects,
and the events that cause objects to change states. These models can
be created and maintained using CASE tools that support
representation of objects and object behavior.
OOA views the world as objects with data structures and behaviors
and events that trigger operations, or object behavior changes, that
change the state of objects. The idea that a system can be viewed as
a population of interacting objects, each of which is an atomic
bundle of data and functionality, is the foundation of object
technology and provides an attractive alternative for the development
of complex systems. This is a radical departure from prior methods of
requirements specification, such as functional decomposition and
structured analysis and design [Yourdon
79].
This technology works best when used in new development. The
experiences of Hewlett-Packard in trying to recapture the
requirements of legacy systems using OOA suggests that the process
can be accomplished only when legacy systems are projected to be
long-lived and frequently updated [Malan
95].
Numerous OOA methods have been described since 1988. These OOA
methods include: Shlaer-Mellor,
Jacobson, Coad-Yourdon, and
Rumbaugh [Baudoin
96]. The results of implementing these methods range from
tremendous successes at AT&T Bell Labs [Kamath
93] to a mixture of successes and partial failures on other
projects. AT&T Bell Labs realized benefits from OOA on a large
project called the Call Attempt Data Collection System (CADCS).
Additionally, they found during the development of two releases of
the CADCS that use of the OOA techniques resulted in an 8% reduction
in requirements specification time and a 30% reduction in
requirements staff effort [Kamath
93]. Other OOA efforts have not been able to reproduce these
successes for reasons such as the lack of completed pilot projects,
and the lack of formal OOA training [Malan
95].
The use of this technology requires a commitment to formal
training in OOA methods. A method of training that has produced
desired results is to initiate pilot projects, conduct formal
classes, employ OOA mentors, and conduct team reviews to train
properly both the analysis and development staff as well as the
program management team [Kamath
93]. There are almost no reported successes using OOA methods
on the first application without this type of training program
[Kamath
93]. Projects with initial and continuing OOA training
programs realize that the benefits of this technology depend upon the
training and experience levels of their staffs. Purchase of CASE
tools that support object-oriented methods may significantly enhance
OOA- this is another cost to consider.
Alternative technologies that are used for developing software
engineering requirements and specifications include functional
decomposition, essential systems analysis, and structured analysis
[Yourdon
79].
There is a strong relationship between OOA and other
object-oriented technologies (see Object-Oriented
Database, Object-Oriented
Design, and Object-Oriented
Programming Languages). This is especially true of
object-oriented design- certain object-oriented methods combine
particular analysis and design methods that work well together. In
fact, the seamless use of objects throughout the analysis, design,
and programming phases provides the greatest benefit. Use of OOA
alone, without transition into OOD, would be a severely limited
approach.
Combining object-oriented methods with Cleanroom
(with its emphasis on rigor, formalisms, and reliability) can define
a process capable of producing results that are reusable,
predictable, and high-quality. Thus, object-oriented methods can be
used for front-end domain analysis and design, and Cleanroom can be
used for life-cycle application engineering [Ett
96].
This technology is classified under the following categories.
Select a category for a list of related topics.
|
[Baudoin 96]
|
Baudoin, Claude & Hollowell, Glenn.
Realizing the Object-Oriented Lifecycle. Upper
Saddle River, NJ: Prentice Hall, 1996.
|
|
[Embley 95]
|
Embley, David W.; Jackson, Robert B.;
& Woodfield, Scott N. "OO Systems Analysis: Is it or
Isn't it?" IEEE Software 12, 2 (July 1995):
19-33.
|
|
[Ett 96]
|
Ett, William & Trammell, Carmen. A
Guide to Integration of Object-Oriented Methods and
Cleanroom Software Engineering [online].
Originally available WWW
<URL:
http://www.asset.com/stars/loral/cleanroom/oo/guidhome.htm>
(1996).
|
|
[Kamath 93]
|
Kamath, Y. H.; Smilan, R. E.; &
Smith, J. G. "Reaping Benefits With Object-Oriented
Technology." AT&T Technical Journal 72, 5
(September/October 1993): 14-24.
|
|
[Malan 95]
|
Malan, R.; Coleman, D.; & Letsinger,
R. "Lessons Learned from the Experiences of Leading-Edge
Object Technology Projects in Hewlett-Packard," 33-46.
Proceedings of Tenth Annual Conference on
Object-Oriented Programming Systems Languages and
Applications. Austin, TX, October 15-19, 1995. Palo
Alto, CA: Hewlett-Packard, 1995.
|
|
[Yourdon 79]
|
Yourdon, E. & Constantine, L.
Structured Design. Englewood Cliffs, NJ: Prentice
Hall, 1979.
|
Mike Bray, Lockheed-Martin Ground Systems
27 Oct 97: updated URL for [Ett 96]
10 Jan 97: original
