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Systems Analysis and Design With UMLSystems Analysis and Design With UML2.02.0

An ObjectAn Object--Oriented Approach, Second EditionOriented Approach, Second Edition

Chapter 1: Introduction to Systems Analysisand Design

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Key Ideas

Many failed systems wereabandoned because analyststried to build wonderful systemswithout understanding theorganization.The primarily goal is to createvalue for the organization.

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Key Ideas

The systems analyst is a key personanalyzing the business, identifyingopportunities for improvement, anddesigning information systems toimplement these ideas.It is important to understand anddevelop through practice the skillsneeded to successfully design andimplement new information systems.

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THE SYSTEMSDEVELOPMENT LIFECYCLE

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Major Attributes of theLifecycle

The projectMoves systematically through phaseswhere each phase has a standard setof outputsProduces project deliverablesUses deliverables in implementationResults in actual information systemUses gradual refinement

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Project Phases

PlanningWhy build the system?

AnalysisWho, what, when, where will the system be?

DesignHow will the system work?

ImplementationSystem delivery

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Project Phases

Phases

Steps

Techniques

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Planning

Planning StepsProject initiation : [System Request ](IS + project sponsor )(approval committee)

Business needBusiness requirementsFeasibility Analysis

Project Management : [Project Plan](approval committee)

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Analysis

Analysis StepsAnalysis Strategy :Analysis of current system (as-is system)Analysis of a new system (to-be system)

Requirement Gathering : Developing a concept for a new system Developing a set of business analysis models

Delivering System Proposal :[analysis and initial design]

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DesignDesign Steps

Design Strategy : Software Package Self-develop Outsourcing

Basic Architecture Design : Software, hardware, and infrastructure Interface design

Database and file spec. :Program deisgn

[System Specification]

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Construction :Installation :[Support Plan] :

Implementation

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Processes andDeliverables

Phase Product

Planning

Analysis

Design

Implementation

Project Plan

System Proposal

SystemSpecification

New System andMaintenance Plan

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THE EVOLUTION OFSYSTEM DEVELOPMENT

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What Is a Methodology?

A formalized approach or seriesof stepsWriting code without a well-thought-out system requestmay work for small programs,but rarely works for large ones.

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Structured Design

Projects move methodicallyfrom one to the next step.Generally, a step is finished

before the next one begins.Waterfall DevelopmentParallel Development

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Waterfall DevelopmentMethod

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Pros and Cons of theWaterfall Method

Pros Cons

Identifies systemsrequirements longbefore programmingbegins

Design must bespecified on paperbefore programmingbegins

Long time betweensystem proposal anddelivery of newsystem

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A “Simple”Process for Making Lunch

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Alternatives to the SDLC

Rapid Application Development(RAD)Phased DevelopmentPrototypingThrow-Away Prototyping

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Rapid ApplicationDevelopment

Critical elementsCASE toolsJAD sessionsFourth generation/visualizationprogramming languagesCode generators

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Rapid ApplicationDevelopment Categories

Phased developmentA series of versions

PrototypingSystem prototyping

Throw-away prototypingDesign prototyping

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How Prototyping Works

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Throwaway Prototyping

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Object-Oriented Analysisand Design

Attempts to balance emphasison data and processUses Unified Modeling Language(UML) for diagramming

Use-case DrivenArchitecture CentricIterative and Incremental

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BASICCHARACTERISTICS OFOBJECT-ORIENTEDSYSTEMS

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Key Elements

Classes -- template to define objects

Instances -- specific examples of classmembers

Objects -- building block of the system

Attributes -- describe data aspects of theobject

Methods -- the processes the object canperform

Messages -- instructions sent to or receivedfrom other objects

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A Class and Its Objects

PATIENT

-Name-Birthdate-Phone Number+Insert ()()+Delete ()()

PATIENT 1: TOP PACKAGE: PATIENT

-Name = Teresa Marks-Birthdate = March 16, 1975-Phone number = 314-997-3456

PATIENT 2: TOP PACKAGE: PATIENT

-Name = Mel Bourne-Birthdate = May 11, 1965-Phone number = 314-997-3219

Attributes

Methods

Class

Instantiated Objects of the Class

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The Key to Reusability

Information hiding is theprinciple that only informationrequired to use the object isavailable outside the objectEncapsulation is the mechanismthat combines data andprocesses in a single object

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Class Hierarchy

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Inheritance

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Polymorphism

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OBJECT-ORIENTEDANALYSIS AND DESIGNUSING UML

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UML

The full UML provides 9separate diagrammingtechniques

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PROJECT TEAM ROLESAND SKILLS

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Information SystemsRoles

Business analystSystem analystInfrastructure analystChange management analystProject manager

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Summary -- Part 1

The Systems Development Lifecycleconsists of four stages: Planning, Analysis,Design, and Implementation

There are three major developmentmethodologies: the waterfall method, RAD,and the Object-Oriented approach.

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Summary -- Part 2There are six major elements in Object-Oriented design: classes, objects,instances, attributes, methods, andmessages.Encapsulation, Inheritance, andPolymorphism are also important object-oriented conceptsThere are five major team roles:business analyst, systems analyst,infrastructure analyst, changemanagement analyst and projectmanager.

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Expanding the Domain

For complete description of UMLsee:www.rational.com/uml