Unit – 1 (Introduction to OOAD)

8/14/2019 Unit 1 (Introduction to OOAD)

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Unit 1 (Introduction to OOAD)

An overview of object oriented systems

development.

Object basics object oriented systems development life

cycle


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Important Programming Models

Procedure OrientedAlgorithms Object Oriented Classes & Objects


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1.Space efficiency

2.Time efficiency

2.1 Worst case efficiency

2.2 Best case efficiency

2.3 Average case efficiency

Algorithm Analysis


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Algorithm analysis (Continued)

1. Worst case efficiency

It is the efficiency for worst case input ( worst case

input is the one for which the algorithm runs longest).

2. Best case efficiency

It is the efficiency for best case input ( best case input is

the one for which the algorithm runs fastest).

3. Average case efficiency

It is the efficiency for Average case input


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Algorithm analysis (Continued)

Case 1:

If the algorithm is depending only on the input size ,

we need not to find best,worst and average case efficiencies

separately.

Case 2:

If the algorithm is depending not onlyon the inputsize ,bust also some factors then find we have to fine

worst,best and average case efficiencies separately.


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Differentiate OOP, OOA & OOD.


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Object Oriented Programming

A language is object oriented if and only if

it satisfies the following requirements:

1.Supports objects

2.Objects have a class

3.Class may inherit attributes from super class.


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Object Oriented Analysis

It is a method of analysis that examinesrequirements from the users.

.contd


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Object Oriented Design

It leads to an object oriented

decomposition.

Uses different notations to expressdifferent models.


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Introduction

System developmentrefers to all activities thatproduces the solution.

System development activities consists ofanalysis, modeling, design, implementation, testing &maintenance.

A software development methodologyis aseries of processes that, if followed , can lead to thedevelopment of an application.


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Object Model

The main principles of object model area) abstraction

b) encapsulation

c) modularityd) hierarchy

e) typing

f) concurrencyg) persistence


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Major Elements of Object Model

a) abstraction

b) encapsulation

c) modularity

d) hierarchy


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Minor Elements of Object Model

a) typing

b) concurrency

c) persistence


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It focuses upon the essential characteristics of

objects.

(e.g.) Project Abstract

a) What is Abstraction?


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b) What is Encapsulation?

Hides the details of the implementation (data &

procedure) of an object(e.g.) Hides the details of the implementation from

clients.

- Provides the interface.


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c) What is Modularity?

The breaking up of something complex

into manageable pieces

Effective Modular design1.Cohesion

2.Coupling


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Ranking or Ordering of abstraction

d-1) What is Hierarchy?

Decreasingabstraction

Increasing

abstraction Vehicle

Elements at the same level of the hierarchyshould be at the same level of abstraction

Car

Ford

Mustang Taurus Thunderbird


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d-2) What is Hierarchy?

At the top of the hierarchy are the most

general classes.

At the bottom are the most specific. A subclass inherits all of the properties &

methods from the superclass.


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e) Typing

It is the enforcement of the class of an

object, such that objects different types

may not be interchanged, or at the most ,

they may be interchange only in veryrestricted ways.

Strong typing prevents mixing

abstractions.


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f) Concurrency

It allows different objects to act at the

same time.

Its the property that distinguishes an

active object from one that is not active.


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g) Persistence

It is the property of an object through

which the object continues exists after its

creator ceases to exists and / or the

objects location moves from the addressphase in which it was created.


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Basic Concepts of Object

Orientation Object

Class

Attribute (Property) Method (Procedure)

Inheritance

Interface (Polymorphism) Relationships

1 ) Wh t i Obj t?


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1a) What is an Object?

It is a combination of data & logic that

represents some real world entity, eitherphysical, conceptual, or software

Physical entity (e.g.) car

Conceptual entity (e.g.) chemical process

Software entity (e.g.) linked list

1b) R ti Obj t


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An object is represented as rectangles

with underlined names

1b) Representing Objects

: Professor

Professor Nandhini

ProfessorNandhini:

Professor

ProfessorNandhini

Object Name Only

Class and Object Name

Class Name Only


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2a) What is a Class?

A class is a set of objects with common

properties (attributes), behavior (operations),

and relationships

- An object is an instance of a class

) C


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A class is represented using acompartmented rectangle

2b) Representing Classes

Professor

Professor Rani

a + b = 10

2 ) Cl C


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2c) Class Compartments

A class is comprised of three sections

The first section contains the class name

The second section shows the structure

(attributes)

The third section shows the behavior(operations)

ProfessornameempID

create( )save( )delete( )change( )

Class Name

Attributes

Operations

2d)The Relationship Bet een


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Objects are grouped into classes

2d)The Relationship Between

Classes and Objects

Objects

Professor Smith

Professor Jones

Professor Mellon

Class

Professor

3 Wh t i Att ib t ?


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3 What is an Attribute?

Class

Example

Attributes

Car

Cost

Color

Manufacturer

Model

Another name properties

It describe the state (data) of an object.


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Define its behavior (what an object is

capable of doing).

CourseOffering

addStudent

deleteStudent

getStartTime

getEndTime

Class

Operation

4) What is method (or) procedure?


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5a) Inheritance

It allows objects to be built from other

objects.

It is a relational ship between classes.

(one class is the parent of other (derived)

class.

The parent class is also known as the

base class (or) super class.

5b) E l Si l I h it


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Account

balancenamenumber

Withdraw()CreateStatement()

Checking

Withdraw()

Savings

GetInterest()Withdraw()

Superclass

(parent)

Subclasses

Generalization

Relationship

Ancestor

Descendents

5b) Example: Single Inheritance

One class inherits from another


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Poly means many

Morph means form

Polymorphism

the same operation maybehave differently on different classes.

Booch defines Polymorphism as the

relationship of objects of many different classes

by some common super class.

6) What is Polymorphism ?


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Association

Aggregation

Dependency

Generalization

Realization

7a) Relationships

7b)Relationships: Association


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Professor UniversityWorks for

Class

Association

Association Name

Professor University

EmployerEmployee

Role Names

7b)Relationships: Association It represents the relationships between objects &

classes.

7c)Relationships: Association


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EmployerEmployee

7c)Relationships: Association It is rendered as a solid line.

It has a name & a role.

Person Company

Person Company

Works for

Association

ROLES

ASSOCIATION NAMESName Direction

Name

Association Role Name


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7d)Relationships: Aggregation

A special form of association that models a

whole-part relationship between an

aggregate (the whole) and its parts


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College Department

Whole

Aggregation

Part

7e) Relationships: Aggregation

(e.g.)

7f) R l ti hi A ti


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Engine wheel

7f) Relationships: Aggregation (e.g.) a car object of other objects such as

engine, seat and wheel objects.

Car

Seat

7g) Relationships: Dependency


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Client Supplier Class

Dependency relationship

7g) Relationships: Dependency

A relationship between two model elements where a

change in one may cause a change in the other Non-structural, using relationship

7h) Relationships: Generalization


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7h) Relationships: Generalization

It is a relationship between a general thing

(called the super class or parent) & a more

specific kind of that thing (called the

subclass or child)

Generalization is an is-a-kind of

relationship

7j) Relationships: Generalization


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7j) Relationships: GeneralizationShape

origin

move( )

resize( )

display( )

Rectangle

Corner : Point

Circle

Corner : Point

Polygon

Points : List

Display

Square Leaf class

Generalization

Base class

7k) Relationships: Realization


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Use Case Use-Case Realization

Canonical form

7k) Relationships: Realization

b) It is used for tracebility


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(continued)

8) Review: Introduction to Object Orientation

What are the four basic principles of objectorientation? Provide a brief description of each.

What is an Object and what is a Class? What is the

difference between them?

What is an Attribute? What is an Operation?

What is an Interface? What is Polymorphism?

Name the 4 basic UML relationships and describe

each.

Describe the strengths of object orientation.

Software Development Life


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Software Development Life

Cycle

System developmentrefers to all activities thatproduces the solution.

System development activities consists ofanalysis, modeling, design, implementation, testing &maintenance.

A software development methodologyis aseries of processes that, if followed , can lead to thedevelopment of an application.


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Linear Sequential Model (Or) Waterfall model

Prototyping model

Evolutionary Model Incremental model

Spiral model

WIN - WIN model

Object oriented model

2e) Software Development Process


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analysis design code test

System/information

engineering

Linear Sequential Model


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(e.g.) The waterfall software development process

What

How

Do It

Test

Use


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Prototyping Model

Customer

Communication Quick Design

BuildPrototype

Customer

evaluation ofPrototype

I t l M d l


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increment 2

increment 3

increment 4

increment 1

delivery of1st increment

delivery of2nd increment

delivery of3rd increment

delivery of4th increment

calendar time

IncrementalModel

S i l M d l


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Spiral Model

CustomerCommunication

Planning

Construction & Release

Customer

Evaluation

Engineering

Risk Analysis

3 ) OO S t D l t A U


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3a) OO System Development : A Usecase

Driven Approach

Using CASE

Tools and/or

OO

programming

languages

Build a Use-Cases

model

Object analysis

Validate test

Design classes, define

attributes and methods

Build object

model

Build User Interface

& Prototype

User satisfaction

& Quality test

Usersatisfaction &

Quality test

3b) OO System Development : A


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3b) OO System Development : A

Usecase Driven Approach

OO System Development includes the

following activities:

OO Analysis

OO Design

Prototyping

Component based development Testing


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4c) OO Analysis

OO analysis includes the following

activities:

Determining the system requirements.

Identifying classes and their relationship to

other class in the problem domain.


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4d) OO Design

OO Design includes the following

activities:

Design the classes.

Design the user interface


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4e) OO Design - Guidelines

Reuse rather than build a new class.

Design a large no. of simple classes rather

than a small no. of complex classes.

Design methods.

Critique what you have proposed. If

possible, go back & refine the classes.

4f) Prototyping


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4f) Prototyping

A version of a software product developedin the early stage of the products life cyclefor specific, experimental purposes.

Easy to understand Types of Prototyping

1.Close ended (or) Throwaway

2.Open ended (or) Evolutionary


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4g) Testing

1.White box testing

2.Black box Testing


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Documents

Unit – 1 (Introduction to OOAD)