Page 22 - DCAP308_OBJECT_ORIENTED_ANALYSIS_AND_DESIGN

Object Oriented Analysis and Design

Notes distance, modeling enterprises, and designing programs and database. We all can agree that
developing a model for a software system, prior to its development or transformation, is as
essential as having a blueprint for large building essential for its construction. Object oriented
models are represented by diagrams. A good model always helps communication among project
teams, and to assure architectural soundness.
It is important to note that with the increasing complexity of systems, importance of modeling
techniques increases. Because of its characteristics Object Oriented Modeling is a suitable modeling
technique for handling a complex system. OOM basically is building a model of an application,
which includes implementation details of the system, during design of the system.

As you know, any system development refers to the initial portion of the software life cycle:
analysis, design, and implementation. During object oriented modeling identification and
organization of application with respect to its domain is done, rather than their final
representation in any specific programming language. We can say that OOM is not language
specific.

Notes Once modeling is done for an application, it can be implemented in any suitable
programming language available.

OOM approach is an encouraging approach in which software developers have to think in terms
of the application domain through most of the software engineering life cycle. In this process,
the developer is forced to identify the inherent concepts of the application. First, developer
organizes and understands the system properly and then finally the details of data structure and
functions are addressed effectively.

Object-oriented modelling is a methodology of analyzing requirements of a system with the
aim of identifying sub-systems with the following desirable properties:
(a) Each subsystem should have clearly specified responsibility of performing a part of overall
task.
(b) Other parts of the sub-system should not have to know how a subsystem performs the task
assigned to it, rather they should only know what task a subsystem does
(c) Each sub-system should be self-contained and independent
(d) Each sub-system should know what other subsystems do and how to send requests to
them for assistance so that it can co-operate with them to get its own job done
(e) Sub-system should hide from outside world the data it uses
(f) The sub-system should be designed to be reusable
Object-oriented modelling is used in practice as it

Facilitates changing of system to improve functionality during the system life time
Facilitates reuse of code of each of the subsystems used to design the large system
Facilitates integrating subsystems into a large system
Facilitates design of distributed systems
An object-oriented modelling is particularly useful in the following situations:
It is required to change an existing system by adding new functionality.

While designing large system and it is found that it can be designed as a collection of
existing reusable objects.

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