OBJECT ORIENTED ANALYSIS FOR EASY UNDERSTANDING .ppt

ITS JUST ABOUT

2. Complexity of software systems
Longevity and evolution of software
systems
High user expectations
2

3. 3
Balanced view between data and computation
Possible to directly represent real world objects in
the computer system
Thus, solves the so-called impedance mismatch
problem.
Software systemReal world
Data-orientedmodel
Software systemReal world
Object-oriented model

4. Approach
•Focuses on improving the maintainabilityand
reusabilityof software systems through a set of
techniques, notations, tools, and criteria.
Activities
•Conceptualization
•Object-oriented analysis and modeling
•Object-oriented design
•Implementation
•Maintenance

5. Analysis
Design
Implementation and unit testing
Integration and system testing
Maintenance

6. Goals
•To define the problem to be solved, i.e., to establish
the functions, services, and constraints of the
software to be developed.
Deliverables
•Requirements specifications itemizing the
functional and nonfunctional requirements, called
system specifications.

7. To find an appropriate solution to a given
problem.
To understand the problem and problem
domain.
Objective of Analysis
To capture a Complete, unambiguous and
consistent picture of the requirements.
What the system must do to satisfy the user ?

8. HencetheANALYSISistheprocessof
transformingaproblemdefinitionfromafuzzy
setoffactsandmythintoacoherentstatement
ofsystem’srequirements.
AnalysisincludesUSER–INTERACTION.

9. Analysis is an iterative process that goes on until the problem
is well understood. Usually difficulties in analysis are
1. Fuzzy Descriptions: Fast response time which leads user
dissatisfaction.
2. Incomplete Requirements : Few requirements which are
important but not included
at the time of analysis.
3. Unnecessary features : Unwanted modules which may effect the
performance may increase complexity,
reduces stability & maintenance of the
system.

10. Deadlines : Time given to deliver a software.
Comparative evaluation –Comparison of new
Software with existing one, may ask a
developer to include extra feature.

11. It is a process of understanding the system requirements
and establishing the goal of an application.
Main intent is to understand User’s need.
Outcome of this phase is
1. To identify Classes and their relationships in
achieving system goal.
2. To understand expected inputs to get desired
outputs or response from system.
Another tool to understand user’s need is preparing a
prototype of user interface

12. IDENTIFY ACTORS
DEVELOP
USE CASES,
ACTIVITY
DIAGRAMS
DEVELOP
INTERACTION
DIAGRAM
DEVELOP
USE CASE,
ACTIVITY
DIAGRAMS
IDENTIFY
CLASSES &
RELATIONSHIP
ATTRIBUTES
& METHODS
REFINE
&
ITERATE

13. Unified Approach
•This approach uses Use Casesto describe the system
from user’s perspective.
•Use Cases are scenarios that describes how actors use
this system
Steps involved in Object Oriented Analysis
•Identifying Actors(Users).
•Develop a simple business process model using UML
activity diagrams.
•Develop use case –which provides comprehensive
documentation of the system under study.
•Prepare interaction diagrams –sequence, collaboration
•Classification –Identify Classes, Relations, Attributes,
methods

14. Business process modeling can be time consuming but it provides
better understanding of the system by using UML diagram.
UML Diagrams are :
•Class Diagram (static)
•Use –Case Diagram
•Behavior Diagram
Interaction Diagrams
Sequence Diagram
Collaboration Diagram
State-chart Diagram
Activity Diagram
•Implementation Diagram
Component Diagram
Deployment Diagram

15. A USE –CASE is a sequence of transactionsin
a system whose task is to submit result of
measurable valueto an individual actorof the
system.
It shows interaction between users and system
Captures the goal and responsibility of system
to its user.
It also describe the events that can be
performed.

16. Identifies classes and relationships among the
subsystem(different modules) of the system.
A Use-Case must have a name with little
description.
Hence it provides an external view of a system or
application.
Explain
•What this application will do and not.
•How the events will take place and can be handled
•UML Class Diagram which also known as OBJECT
MODEL represents internal view of an system.

17. It uses the words like -Uses & extends Association
•Sometime we must use a use case without defining
it again and again which occurs more than one time
in a system for example in a library process
Checking Library card may occur while borrowing
book, returning book, for getting interlibrary loan
etc hence in such a situation we can write uses on
the arrow in use case diagram.
•Can use term extends for to expand the common
behavior to fit the special circumstances.
•Use-Case can be divided into packages.

18. Common Cover –All must share same cover.
80-20 Rule –80 % work to be done with 20%
documentation.
Familiar vocabulary –Well known language
must be used.
Document must be short as much we can but
must give a clear idea about the system.
Provide Appendix, and some guidelines to assit
reader.

19. Identification of Classes is the hardest part of
Object oriented analysis & design.
Classification is the process of checking to see
if an object belongs to a category or a class.
Classes are important mechanism for
classifying objects.
Class is a Specification of structure, behavior
and the description of an object.
Some says it provides conceptual building
blocks for designing system.

20. In this method Noun is a textual description
that can be considered as classes.
Verbs to be method.
All plurals are changed to singular and nouns
are listed.
This List can be divided into three categories:
•Fuzzy Classes ( classes we are not sure about ).
•Relevant Class.
•Irrelevant Class.

21. Look for nouns and noun phrase in use-case.
Some classes are implicit or taken from general
knowledge.
All selected classes must make a sense in
application domain.
Choose Classes and define class names.

22. Redundant classes : Don’t select two classes
that express the same information.
If more than word is used for a class name
select the word which is more meaningful
•Ex. Pin Codecan be taken as PIN.
Be careful about –that the object represented
by noun behave differently when the adjective
is applied.
Tentative objects that are used only as values
should be defined as attributes not as class.