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OOAD. Object Oriented Analysis and Design Methodology. Today’s Discussion. Background – Why OO is hot OO Methodology – Java Factory Approach Hands on application of CRC Methodology Informal Questions anytime Food and Drink anytime. Object Oriented Headlines.

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OOAD

Object Oriented Analysis and Design Methodology


Today’s Discussion

  • Background – Why OO is hot

  • OO Methodology – Java Factory Approach

  • Hands on application of CRC Methodology

  • Informal

    • Questions anytime

    • Food and Drink anytime


Object Oriented Headlines

“Object-Oriented Technology Ventures Into the Real World”

“IBM unveils new object-oriented middleware”

“Expo to serve up object-oriented products”

“Object-Oriented is Here to Stay”


Motivation For OOAD

Traditional Methodologies are broken because…

  • They haven’t solved problems of quality and timeliness.

  • They separates data from procedures making software reusability more difficult.

  • They don’t work well in our non-linear world.


Linear vs. Non-linear

Linear

Non-Linear

Page 1

Page 2

Step 1

Step 2

Page 3

Page 4

Step 3


OOAD Vs. Traditional Approach

  • Process is less rigorous

    • Analysis Paralysis

  • Process is more fluid

    • Waterfall vs. Onion

  • No definitive stopping point

    • How many iterations?

  • More Trial and Error…

    “I failed my way to success.”

    Thomas Edison


OOAD Methodology Roots

  • Unified Modeling Language(UML)

    • Use Cases

    • Class Diagrams

  • Sun Microsystems Java factory

    • CRC Methodology

      • Class

      • Responsibility

      • Collaboration


Defining the Process

  • Determine the Requirements

  • Identify the Classes and Objects

  • Describe the Object Collaborations and the classes

  • Sketch the User Interface


Diagram of OOAD

Class Diagram

Determine

Requirements

Identify Classes & Objects

Describe Collaboration

Sketch Interface

ColloborationDiagrams

Interface Sketch

Summary

CRC Cards


Determining Requirements

  • Summary Paragraph

    • Define general approach to solving problem

    • Emphasize the what and not the how

    • Describe all major functions(operations/methods)

    • Define boundaries


Sample Problem Summary


Identifying Classes and Objects

  • CRC Card Preparation

    • Class(data attributes)

    • Responsibility(Message response)

    • Collaboration(Class interaction)


Class Definition

  • Classes are the templates or blueprints for objects

  • Classes define the attributes and behavior(methods) for objects

  • Objects contain the data and the methods

  • Objects are the nouns of the Object Oriented world


So how do you define Classes??

1) Read Problem Summary statement for nouns and noun phrases which may be physical objects, concepts, categories of objects or attributes of other objects. Create a list of all of these items.

2) Review list for Class candidates. Transfer classes to CRC card.


Sample Problem Summary


Noun Phrases

  • Renter Application

  • Bugs

  • Inventory

  • User

  • Message


Transitioning Nouns to Classes

  • Not always easy

  • Iterative

  • Experience

  • Steps…

    • Logical Groupings and Leveling

    • Identify Implied Classes

    • Eliminate noise(primitives, attributes, messages)

“Design Decisions have no obvious right and wrong answers.”


Renter Application

Bugs

Inventory

User

Message

Logical Groupings/Leveling

Implied Classes

Noise elimination

Noun Phrases Class Steps


So what are the Classes of the Bug Rental Application??

  • Renter

  • Lender

  • Inventory


CRC Card - Front

Class: Renter

Responsibilities:

Collaborations:

(Front of Card)


Defining Responsibilities

  • Use Problem Statement to identify verbs

  • Logical group and organize action items

  • Match Method to Class

  • Adjust for any omissions


Track Inventory

Rent Bug

Decrease Inventory

Return Bug

Increase Inventory

Display Message

Logical Grouping

Leveling

Match Method to Class

Method Verbs Identification


Renter

Rent Bug

Return Bug

Display Message

Lender

Rent Bug

Return Bug

Supply Message

Bug Rental Methods


Describing Collaboration

  • Develop Use-case scenarios

    • Sequence of related events

  • Walk Through Use-cases

    • Identify message exchanges

    • Identify missed Classes


Identify Use-Case Scenarios

  • Customer Rents a Bug

    • ) Customer enters request for bug

    • ) Lender checks inventory for bug availability

    • ) If inventory is greater than zero

      • Inventory is decreased by one

      • Bug is made available to Customer

      • Message is sent to Customer from Lender

    • ) If inventory is zero, error message is sent to customer from Lender


Now it’s your turn…Develop Use-Case for Bug Returns

  • Customer returns bug

  • Lender increases inventory

  • Lender sends message to Customer


CRC Card - Front

Class: Renter

Collaborations:

Responsibilities:

Lender

Lender

N/A

Rent Bug

Return Bug

Display Message

(Front of Card)


Identifying Attributes

  • Characteristics of Class

  • Adjectives of the Object Oriented World

  • Inventory Example

    • Bug ID

    • Bug Description

    • Bug Version


Your turn again…Develop some common attributes for the Renter

  • Customer Name

  • Customer Address

  • Customer Status

  • Customer Rentals

  • Customer Balance


CRC Card - Back

Attributes:


Developing a Class Diagram

Class Name

Attributes

Methods


CRC Adjustments

  • Create new CRC cards

  • Trash invalid CRC cards

  • Challenge yourself

    • Not a cookbook

    • Process is not magic;requires critical thinking skills

  • Iterate!


Next Step...

  • Onion Peeling(aka Iterate)

  • Evolve From What to How

    • From abstract to detailed functionality

    • Define Data Access

    • Define Physical environment


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