Introduction to Object-Oriented Analysis and Design

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Introduction to Object-Oriented Analysis and
Design
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Course Topics

• Introduction to Object Oriented Analysis and
  Design
• Object-Oriented Concepts
• Visual Modeling with UML
• Developing Object-Oriented Systems
• Transition from OO models to code
• Distributed architecture
• OO and Persistence

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Introduction to OOAD
In this module

• What is Object-Oriented Technology?
• Definition
• Benefits
• Tools and languages
• OO Development Process
• Contrast of OO Methodology to Structured
  Methodology

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What Is Object Technology?

• Object Technology
• A set of principles guiding software
  construction, together with languages, databases
  and other tools that support those principles.
• David Taylor Object Technology A Managers
  Guide
• A continuum of ideas and practices for software
  analysis, design and programming that focuses on
  objects and their interactions rather than
  processes and data

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What is OOAD?

• OOAD stands for Object-Oriented Analysis and
  Design
• Object-Oriented Analysis focuses on finding and
  describing objects or concepts in the problem
  domain
• Object-Oriented Design focuses on
• Defining and detailing the software objects found
  in OO Analysis
• How software objects interact to fulfill the
  requirements

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What is OOP?

• OOP is Object-Oriented Programming
• OOP requires the developer to think of the
  software solution in a different way
• It requires the use of an object-oriented
  language
• OOP together with OOAD and OO testing form what
  is called Object-Oriented Technology

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Benefits of Object Technology

• Some of the strengths of OO technology
• Reflects real world entities more closely
• Encourages architectural, design and code reuse
• Promotes a consistent communication technique
  that is understandable by both business and
  technical participants
• Builds systems that are more easily extended or
  changed
• Promotes quality of solutions
• Works well for large, complex software systems

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Object-Oriented Languages

• Simula67 Recognized as the first OO language
• Smalltalk (1972)
• C popular in the late 80s and early 90s
• Java replaced C in late 90s and is still the
  most popular language today

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Other OO Languages

• Eiffel
• Designed by Bertrand Meyer at Interactive
  Software Engineering
• C
• A Microsoft created language as a part of the
  .NET initiative
• Ruby
• Created by Yukihiro Matsumoto and released it to
  the public in 1995
• Python
• A high-level programming language first released
  by Guido van Rossum in 1991
• Visual Basic .NET
• Another .NET language that coincided with C

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Popular OO Languages

• Four OO programming languages seem to dominate
  the development world today
• C
• Java
• Visual Basic
• C
• The single major design language Unified
  Modeling Language (UML) is universally accepted
• Used to design OO systems
• Managed by the Object Management Group
• Currently on version 2.1

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Software Development Methodologies

• Methodology (noun) the organizing principles
  underlying a particular focus area an approach
  a set of processes and guidelines governing an
  area of study
• In software development, we are talking about the
  approach to developing a software solution for a
  technical or procedural problem
• Often referred to as the Software Development
  Life Cycle (SDLC) approach

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Software Development Methodologies

• Structured Development typically accomplished
  with a Waterfall Process
• Object-Oriented Development typically
  accomplished with a Unified Process
• Other popular development processes
• Rapid Application Development (RAD)
• Agile
• eXtreme Programming (XP)

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Structured Analysis and Design

• The Procedural approach to building systems
  focuses on separate procedures and their data
• Procedural programs allow us to view an
  application as commands to be executed
  sequentially
• Design models are created far in advance of
  implementation
• The focus is on the data and how it flows from
  process to process

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Object-Oriented Analysis and Design

• Object-Oriented programming focuses on separate
  objects and their data
• Object-Oriented systems allow us to view a system
  as objects which encapsulate state and behavior
• Object-Oriented design models are developed close
  to implementation
• Object-Oriented systems promote re-use of
  programming elements

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OO Development Objectives

• Qualities of an Object-Oriented System
• Reusability
• Reliability
• Robustness
• Extensibility
• Maintainability

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Development Objectives Reusability

• Reusability (reusable components)
• The ability to create and reuse architectural
  components of a system
• Reduces redundant development efforts by creating
  or purchasing reusable frameworks, components and
  service objects
• Components can be used on many projects without
  re-inventing them

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Development Objectives Reliability

• Reliability
• Components can be honed over time because they
  are separate entities
• Improves usefulness and reliability without
  affecting or degrading other parts of a system

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Development Objectives Robustness

• Robustness
• The ability of a system to continue to operate
  correctly across a wide range of operational
  conditions and to fail gracefully outside of that
  range
• Often called flexibility
• The OO development process is designed to help
  the project team develop fully functional
  applications using precise analysis, design and
  coding techniques
• As the system evolves, frequent testing is
  imposed to verify robustness

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Development Objectives Extensibility

• Extensibility
• The ability to add new features to a program
  without disturbing any existing code
• Accomplished by creating modular (loosely
  coupled) objects and components that can be
  altered or enhanced without disturbing code in
  other parts of the application
• Applications can have a longer life if they are
  relatively easy to modify incorporating
  changing user needs

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Development Objectives Maintainability

• Maintainability
• The ease with which a software system or
  component can be modified to correct faults,
  improve performance or other attributes, or adapt
  to a changed environment (IEEE definition)
• Good OO design creates systems that are
  partitioned and encapsulated to afford change
  without a rippling effect

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Waterfall Process
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Unified Process
Disciplines
Business Modeling Requirements Analysis and
Design Implementation Test Deployment Configuratio
n Mgmnt Project Management Environment
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Releases and Phases
Unified Process

• One pass through the phases of any lifecycle
  delivers a release of a product
• In iterative development, number of iterations
  within each phase varies
• Size, complexity, .
• Each discipline occurs within each iteration
• More or less emphasis depending on Phase

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Unified Process Phases

• Overview of the Unified Process
• The Four Phases
• Inception
• Elaboration
• Construction
• Transition

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The Four Phases

• The Life cycle contains four Phases
• One execution of a lifecycle delivers a Release
• The end of each phase is a Milestone

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Inception Phase Milestone

• Here we
• Define objectives for the system under
  development
• Stakeholders agree on scope, cost and schedule
• Requirements identified and prioritized
• Project plan in place schedule, scope, budget,
  risk, quality, procurement, staffing,
  communications, configuration
• Model the business using Activity diagrams and/or
  Class diagrams
• Create Use Case diagrams

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Elaboration Phase Milestone

• Here we
• Define the baseline architecture
• Vision statement and requirements are stable
• Architecture is stable
• Iteration plans are ready
• Stakeholders agree on scope, cost and schedule
• Refine Use Case diagrams
• Create Activity and Interaction diagrams for Use
  Case scenarios
• Create Analysis models using Class diagrams

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Construction Phase Milestone

• Here we
• Establish the initial operational capability
• Product is stable and ready to be released
• Stakeholders are ready to implement it
• Planned expenditure for deployment is acceptable
• Create Design models using Class diagrams
• Create or refine Component diagrams

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Transition Phase Milestone

• Here we
• Deliver the system and place it in production
• User is satisfied
• Resource estimates for ongoing operation are
  acceptable
• Create Deployment diagram
• Could be created at an earlier phase

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Reviews and Iterations

• Each phase contains one or more Iterations
• Depending upon project size, complexity,.
• A review is conducted after each iteration

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Principles of OO Programming

• These concepts are fundamental to OO programming
• Objects
• Encapsulation
• Messages
• An object-oriented software solution consists of
  a group of well defined objects that exploit
  encapsulation and that communicate through
  messages

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What is an Object?

• Object
• An entity, concept or thing in your software
  solution
• Has state or data (in the form of variables)
• Has behavior or operations (in the form of
  functions)
• Is an instance of an abstract data type

Example a Valve Data - serial number -
capacity - open/closed Operations - open
- close - adjust flow
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What is Encapsulation?

• Encapsulation
• Packaging data together with its corresponding
  methods
• A technique to accomplish data hiding

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What is a Message?

• Message
• A signal from one object to another
• Requests the receiving object to execute one of
  its methods
• Typically accomplished with a function call

aValve.open()
aController
aValve
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Contrast of Procedural and OO

• Problem
• Design a personalized banking system that
  contains a collection of transactions that add
  to, and subtract from, a running balance. Print
  out the list of transactions, sorted by date and
  show the final balance

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A Procedural Solution

• There is much processing behind each of these
  boxes
• What happens if the format for the date of each
  transaction changes like going from a two-digit
  year to a four-digit year?

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An Object-Oriented Solution
sort()
name J. Doe balance 50 pinNum 2345
printMonthlyStmt()
getAmt()
amt
anAcct
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Review

• In your own words, define object-oriented
  technology
• What are some of the benefits of OO technology?
• What are the two software development
  technologies discussed here?
• What are the characteristics of an OO system that
  distinguish it from a procedural system?

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Any Questions?