Systems Analysis and Design Third Edition Planning

PowerPoint Presentation for Dennis, Wixom & Roth Systems Analysis and Design, 3rd EditionCopyright 2006 © John Wiley & Sons, Inc. All rights reserved.3 - 1

Systems Analysis and DesignSystems Analysis and DesignThird EditionThird Edition

Alan Dennis, Barbara Haley Wixom, and Roberta RothJohn Wiley & Sons, Inc.

Slides by Candace S. Garrod Red Rocks Community College


PlanningPlanning

Chapter 1


The Systems Development Life Cycle(SDLC)

PowerPoint Presentation for Dennis, Wixom, & Roth Systems Analysis and Design, 3rd EditionCopyright 2006 © John Wiley & Sons, Inc. All rights reserved.1 - 4

The SDLC is composed of fourfundamental phases:

PlanningAnalysisDesignImplementation


Each of the phases include a set ofsteps, which rely on techniques thatproduce specific document files thatprovide understanding about theproject.


To Understand the SDLC:Each phase consists of steps that leadto specific deliverablesThe system evolves through gradualrefinement


Phase I: Planning


This phase is the fundamental processof understanding why an informationsystem should be built.The Planning phase will also determinehow the project team will go aboutbuilding the information system.The Planning phase is composed of twoplanning steps.


Two Planning Steps


During project initiation, the system’sbusiness value to the organization isidentified (How will it lower costs or increaserevenues?)

During project management, the projectmanager creates a work plan, staffs theproject, and puts techniques in place to helpthe project team control and direct the projectthrough the entire SDLC.


Phase II: Analysis


The analysis phase answers the questions ofwho will use the system, what the system willdo, and where and when it will be used.During this phase the project teaminvestigates any current system(s), identifiesimprovement opportunities, and develops aconcept for the new system.This phase has three analysis steps.


Three Analysis StepsAnalysis strategy: This is developed to

guide the projects team’s efforts. Thisincludes an analysis of the current system.

Requirements gathering: The analysis ofthis information leads to the development ofa concept for a new system. This concept isused to build a set of analysis models.

System proposal: The proposal ispresented to the project sponsor and otherkey individuals who decide whether theproject should continue to move forward.


The system proposal is the initial deliverablethat describes what business requirements thenew system should meet.The deliverable from this phase is both ananalysis and a high-level initial design for thenew system.


Phase III: Design


In this phases it is decided how thesystem will operate, in terms of thehardware, software, and networkinfrastructure; the user interface, forms,and reports that will be used; and thespecific programs, databases, and filesthat will be needed.


Five Design StepsDesign Strategy: This clarifies whether the

system will be developed by the company oroutside the company.

Architecture Design: This describes thehardware, software, and networkinfrastructure that will be used.

Database and File Specifications: Thesedocuments define what and where the datawill be stored.

Program Design: Defines what programsneed to be written and what they will do.


Phase IV: Implementation


During this phase, the system is eitherdeveloped or purchased (in the case ofpackaged software).This phase is usually the longest andmost expensive part of the process.The phase has three steps.


Three Implementation Steps


System Construction: The system isbuilt and tested to make sure it performsas designed.Installation: Prepare to support theinstalled system.Support Plan: Includes a post-implementation review.


Systems Development Methodologies


A methodology is a formalized approachto implementing the SDLC.The methodology will vary depending onwhether the emphasis is on businessesprocesses or on the data that supportsthe business.


Process-centered Methodologies

With this methodology, the focus is on definingthe activities associated with the system.The concentration is on representing thesystem concept as a set of processes withinformation flowing into and out of theprocesses.


Data-centered Methodologies


This methodology focuses on definingthe content of the data storagecontainers and how they are organized.Data-centered methodologies utilizedata models as the core of the systemconcept.


Object-oriented Methodologies


This methodology attempts to balancethe focus between processes and data.The Unified Modeling Language (UML)is used to describe the system conceptas a collection of objects incorporatingboth data and processes.


Category I of the SystemDevelopment Methodology:

Structured Design


Structured design methodologies adopt aformal step-by-step approach to the SDLC thatmoves logically from one phase to the next.This design methodology introduces the use offormal modeling or diagramming techniques todescribe a system’s basic business processesand follows a basic approach of two structureddesign categories.


Waterfall Development


With waterfall development- basedmethodologies, the analysts and users proceedsequentially from one phase to the next.The two key advantages of waterfalldevelopment-based methodologies are:

- The system requirements are identified longbefore programming begins.- Changes to the requirements are minimized asthe project proceeds.


The two key disadvantages of waterfalldevelopment-based methodologies are:

- The design must be completely specifiedbefore programming begins.

- A long time elapses between thecompletion of the system proposal in theanalysis phase and the delivery of the system.


Waterfall Development-based Methodology


Parallel Development


This methodology attempts to addressthe long time interval between theanalysis phase and the delivery of thesystem.


A general design for the entire system is performed andthen the project is divided into a series of distinctsubprojects.


Category II of the SystemDevelopment Methodology: RapidApplication Development (RAD)


RAD-based methodologies adjust the SDLCphases to get some part of system developedquickly and into the hands of the users.Most RAD-based methodologies recommendthat analysts use special techniques andcomputer tools to speed up the analysis,design, and implementation phases, such asCASE (computer-aided software engineering)tools.


One possible subtle problem with RAD-basedmethodologies is managing user expectations.


Phased Development


This methodology breaks the overall systeminto a series of versions that are developedsequentially.The team categorizes the requirements into aseries of versions, then the most importantand fundamental requirements are bundledinto the first version of the system.The analysis phase then leads into design andimplementation; however, only with the set ofrequirements identified for version 1.As each version is completed, the team beginswork on a new version.


Phased Development-based Methodology


Prototyping


Prototyping-based methodologies perform theanalysis, design and implementation phasesconcurrently.All three phases are performed repeatedly in acycle until the system is completed.A prototype is a smaller version of the systemwith a minimal amount of features.


Prototyping-based Methodology


Advantage: Provides a system for theusers to interact with, even if it is notinitially ready for use.Disadvantage: Often the prototypeundergoes such significant changes thatmany initial design decisions prove to bepoor ones.


Throwaway Prototyping


Throwaway prototyping methodologiesare similar to prototyping basedmethodologies.The main difference is that throwawayprototyping IS completed during adifferent point in the SDLC.Has relatively thorough analysis phase.


Throwaway Prototyping-based Methodology


Category III of the SystemDevelopment Methodology: Agile

Development


This category focuses on streamlining theSDLC by eliminating much of the modelingand documentation overhead and the timespent on those tasks.Projects emphasize simple, iterativeapplication development.This category uses extreme programming,which is described next.


Extreme Programming (XP)


Extreme Programming (XP) wasfounded on four core values:

CommunicationSimplicityFeedbackCourage


Key principles of XP include:Continuous testingSimple codingClose interaction with the end users tobuild systems very quickly


An Extreme Programming-basedMethodology


Selecting the AppropriateDevelopment Methodology


Selecting a methodology is not simple,as no one methodology is always best.Many organizations have their ownstandards.The next figure summarizes someimportant methodology selection criteria.


Criteria for Selecting aMethodology


Clarity of User Requirements

RAD methodologies of prototyping andthrowaway prototyping are usually moreappropriate when user requirements areunclear as they provide prototypes forusers to interact with early in the SDLC.


Familiarity with Technology

If the system is designed without somefamiliarity with the base technology,risks increase because the tools may notbe capable of doing what is needed.


System ComplexityComplex systems require careful anddetailed analysis and design.Project teams who follow phaseddevelopment-based methodologies tendto devote less attention to the analysis ofthe complete problem domain than theymight if they were using othermethodologies.


System Reliability

System reliability is usually an importantfactor in system development.Throwaway prototyping-basedmethodologies are most appropriatewhen system reliability is a high priority.Prototyping-based methodologies aregenerally not a good choice as they lackcareful analysis and design phases.


Short Time Schedules

RAD-based methodologies are wellsuited for projects with short timeschedules as they increase speed.Waterfall-based methodologies are theworst choice when time is essential asthey do not allow for easy schedulechanges.


Schedule Visibility

RAD-based methodologies move manyof the critical design decisions earlier inthe project; consequently, this helpsproject managers recognize andaddress risk factors and keepexpectations high.


Project Team Skills and RolesProjects should consist of a variety of skilledindividuals in order for a system to besuccessful.Six major skill sets an analyst should haveinclude:

TechnicalBusinessAnalyticalInterpersonalManagementEthical


Categories of Analysts

Business AnalystSystems AnalystInfrastructure AnalystChange Management AnalystProject Manager


Project Team Roles


SummaryThe Systems Development Lifecycle consistsof four stages: Planning, Analysis, Design, andImplementationThere are six major developmentmethodologies: the waterfall method, theparallel development method, the phaseddevelopment method, system prototyping,design prototyping, and agile development.There are five major team roles: businessanalyst, systems analyst, infrastructureanalyst, change management analyst andproject manager.


Copyright © 2006John Wiley & Sons, Inc.

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Systems Analysis and Design Third Edition Planning

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