Lect1

Object Oriented Analysis&

Design

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Syllabus

• Two views of software Developments:• SSAD and OOAD.• Why Object –Orientation?

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Systems development life cycle (SDLC)• SDLC: process of building, deploying,

using, and updating an information system

Plan

DevelopUse &

Maintain

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System development methodology

• SD Methodlogy – Guidelines for developing system. – Kind of knowledge.

• Two kinds of methodologies – Structured (since 1970s)– Newer, rapid development

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Structured methodology

Also called “Waterfall” methodology

INSTALLATION, TESTING

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Waterfall Model – from ‘what’ to ‘use’

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Software Development Process

7

Requirement Specification

System Analysis

System Design

Testing

Implementation

Maintenance

Deployment

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8


System Analysis

System Design

Testing

Implementation

Maintenance

Deployment

A formal process that seeks to understand the problem and document in detail what the software system needs to do. This phase involves close interaction between users and designers.

Most of the examples in this book are simple, and their requirements are clearly stated. In the real world, however, problems are not well defined. You need to study a problem carefully to identify its requirements. 04/08/2023

System Analysis

9


System Analysis

System Design

Testing

Implementation

Maintenance

Deployment

Seeks to analyze the business process in terms of data flow, and to identify the system’s input and output.

Part of the analysis entails modeling the system’s behavior. The model is intended to capture the essential elements of the system and to define services to the system.

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System Design

10


System Analysis

System Design

Testing

Implementation

Maintenance

Deployment

The process of designing the system’s components.

This phase involves the use of many levels of abstraction to decompose the problem into manageable components, identify classes and interfaces, and establish relationships among the classes and interfaces.04/08/2023

Implementation

11


System Analysis

System Design

Testing

Implementation

Maintenance

Deployment

The process of translating the system design into programs. Separate programs are written for each component and put to work together.

This phase requires the use of a programming language like Java. The implementation involves coding, testing, and debugging.

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Testing

12


System Analysis

System Design

Testing

Implementation

Maintenance

Deployment

Ensures that the code meets the requirements specification and weeds out bugs.

An independent team of software engineers not involved in the design and implementation of the project usually conducts such testing.

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Deployment

13


System Analysis

System Design

Testing

Implementation

Maintenance

Deployment

Deployment makes the project available for use.

For a Java applet, this means installing it on a Web server; for a Java application, installing it on the client's computer.

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Relationships among Classes

• Association

• Aggregation

• Composition

• Inheritance

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Association

Association represents a general binary relationship that describes an activity between two classes.

15

Student * 5..60 Take Teach

0..3 1 Teacher

Faculty Course

An association is usually represented as a data field in the

class.

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Association Between Same Class

Association may exist between objects of the same class. For example, a person may have a supervisor.

16

Person Supervisor

1

1

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Aggregation and CompositionAggregation is a special form of association, which represents an ownership relationship between two classes. Aggregation models the has-a relationship. If an object is exclusively owned by an aggregated object, the relationship between the object and its aggregated object is referred to as composition.

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Name Address Person

Composition Aggregation

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Aggregation and Composition

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What is a navigable association in UML?Associations are relationships between classes in a UML Class Diagram. They are represented by a solid line between classes. Associations are typically named using a verb or verb phrase which reflects the real world problem domain. The normal kind of association is bidirectional by default. This means that if an association exists between two classes, then both objects know about each other. However, when creating a class diagram it is possible to use a navigable association between two classes. This is shown by adding an arrowhead at one end of the association.

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What is a navigable association in UML?

If “A” is the source class and “B” is the target class, the

arrowhead would be placed on the “B” side of the

association. A navigable association of this type means

that at runtime object “A” knows about object “B”, but

object “B” has no knowledge of or visibility into object

“A”.

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StaffMember Student1..* *instructs

instructor

Association name

Role name

MultiplicityNavigable

(uni-directional) association

Courses

pre - requisites

0..3Reflexive

association

Role

*

Inheritance

Inheritance models the is-an-extension-of relationship between two classes.

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Person Faculty

public class Faculty extends Person {

/** Data fields */

/** Constructors */

/** Methods */

}

(A) (B)

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Objects

• An object is an individual unit which is used as the basic building block of programs. The term object is also used to refer to any "thing".

• Each object is capable of receiving messages, processing data, and sending messages to other objects.

• Each object can be viewed as an independent little machine or actor with a distinct role or responsibility.

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Object – key concept

• Object: Thing (data structure) with data (attributes) and methods (behaviors, processes, operations)

• Object “encapsulates” data and processes

• Examples of objects– Problem domain objects (student, customer)– User interface (buttons, text boxes)

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Object examples

Objects are associated and interact via messages.

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Classes

• Classes are used to group related variables and functions.

• A class specifies the structure of data which contains methods (functions) which manipulate the data of the object and perform tasks. A method is a function with a special property that it has access to data stored in an object.

• A class is the most specific type of an object in relation to a specific layer. A class may also have a representation (meta-object) at run-time, which provides run-time support for manipulating the class-related metadata.

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Class• Class: Defines what all objects of a class

represent• Objects are instances of a class (Customer

object is an instance of a customer class)

Name

Attributes

Operations

Object – An instance of class with specified Values of Attributes (specific data)

1200509/10/2003

16/10/2003

Class

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Inheritance & Specialization/Generalization

Inheritance: Property of OO systems allowing for attributes and methods to be shared among objects.

Inheritance enables a special association between classes called Specialization/Generalization

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Inheritance & Specialization/ Generalization (Cont.)

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• Specialization: Subclasses inherit attributes and operations of the super-class, plus have some of their own.

• Subclasses “specialize”

the super-class.

• Generalization represented by arrows from subclasses to super-class. • Class “generalizes”

attributes & methods of sub-classes.

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Each type of vehicle has its own version of calcPrice()

Message: ”Calculate price”

Inheritance and Polymorphism• Polymorphism: Ability for dissimilar objects to respond

to the same message in different ways.

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Ex. Inheritance for graphic figures: Each subclass inherits the attributes, operations, and associations of its superclasses

Figure

Color

center Position

penThickness

penType

Move

Select

Rotate

display

Diagram

name

ZeroDimensionalOneDimensional

orientation

scale

TwoDimensionalOrientation

fillType

Scale

fill

Point

display

Line

endPoints

display

ArcRadius

startAngle

arcAngle

display

Spline

controlPts

display

Polygon

numOfSides

verticesdisplay

Circle

diameter

Display

rotate

Radius

startAngle

arcAngle

display

ArcRadius

startAngle

arcAngle

display

ArcRadius

startAngle

arcAngle

display

ArcRadius

startAngle

arcAngle

display

ArcRadius

startAngle

arcAngle

display

1 *

dimensionality

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Specialization (EER – ENHANCED OR EXTENDED ENTITY RELATIONSHIP)

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• Generalization is the reverse of the specialization process • Several classes with common features are generalized into a

super-class; – original classes become its subclasses

• Example: CAR, TRUCK generalized into VEHICLE; – both CAR, TRUCK become subclasses of the super-class VEHICLE.– We can view {CAR, TRUCK} as a specialization of VEHICLE – Alternatively, we can view VEHICLE as a generalization of CAR

and TRUCK

Generalization

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Generalization

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Generalization

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Specialization

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Object Oriented Development

• The process of converting a problem specification into an object

oriented program is called as object oriented development.

• This program consists of a group of objects which communicates

with one another.

• These objects can be created or destroyed while the programs

execution as per the need.

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Problems in Shifting from the Traditional Approach to Object Oriented Development are :

• Initially, the whole process becomes very tedious because – OO S/W must coexist with the legacy s/w.Stored data is in relational databases & now it must be

converted into objects.

Initially, we do not get experienced people to work with.The staff needs proper training to understand & employ

the OO development & infrastructure.

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Contd.

Project Management is pervaded (spread)As the project leaders are not well Knowledgeable

with the new technology, architectural flaws cannot be detected in the early stages

Estimation & planning also fails up to some extent.As most of the estimation models rely upon the

previous data, so a level of mismanagement occurs.

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Lect1

Documents

Transcript of Lect1