信息時(shí)代的管理信息系統(tǒng)-Chap6

Chapter6

SystemsDevelopment:Phases,Tools,andTechniquesCopyright?2010bytheMcGraw-HillCompanies,Inc.Allrightsreserved.McGraw-Hill/IrwinSTUDENTLEARNINGOUTCOMESDefinethetraditionalsystemsdevelopmentlifecycle(SDLC)anddescribethe7majorphaseswithinit.Compareandcontrastthevariouscomponent-baseddevelopmentmethodologies.DescribetheselfsourcingprocessasanalternativetothetraditionalSDLC.6-2STUDENTLEARNINGOUTCOMESDiscusstheimportanceofprototypingandprototypingwithinanysystemsdevelopmentmethodologyDescribetheoutsourcingenvironmentandhowoutsourcingworks.6-3SAVINGLIVESTHROUGHSYSTEMSDEVELOPMENTCentersforDiseaseControl(CDC)tracksawealthofinformationAntimicrobial-resistantinfectionsinhospitalsInfluenzaoutbreaksTerroristbiochemicalattacksBacteriacountsinriversandstagnantponds,etcUnfortunately,mostofthatinformationisstoredinseparateITsystemsthatdonotcommunicatewitheachother6-4SAVINGLIVESTHROUGHSYSTEMSDEVELOPMENTTheCDCisusingaservice-orientedarchitecture(SoA)tointegrateallthosesystemsandinformationAnSoAtreatseverycomponentofanITsystem–adatabasefile,aserver,aCRMsoftwaresolution,etc–asabuildingblockWithinanSoA,thosebuildingblockscanbe“pluggedandplayed”sothateverythingworkstogetherinanintegratedfashion6-5SAVINGLIVESTHROUGHSYSTEMSDEVELOPMENTAllcomputersuseacommonbinarybaselanguage.Thatbeingtrue,whyisitsodifficulttogetcomputersystemstoeasilycommunicatewitheachother?Insystemsdevelopment,prototypingisusedtobuildamodelofaproposedsystem.Howhaveyouusedprototypinginyourlife?Outsourcing–goingtoanothercompanyforsystemsdevelopment–isbigbusiness.WhywouldtheCDCnotwanttopursueoutsourcing?6-6INTRODUCTIONInformationsystemsarethesupportstructureformeetingthecompany’sstrategiesandgoalsNewsystemsarecreatedbecauseemployeesrequestthemNewsystemsarecreatedtoobtainacompetitiveadvantage6-7INTRODUCTIONWhendevelopinganewsystem,youhave3“who”choices…Insourcing

–ITspecialistsinsideyourorganizationSelfsourcing–do-it-yourselfapproachmanyenduserstakewithlittleornohelpfromITspecialistsOutsourcing–athird-partyorganization(i.e.,letsomeonedotheworkandpaythemforit)6-8CHAPTERORGANIZATIONInsourcingandtheSDLCLearningoutcome#1Component-BasedDevelopmentLearningoutcome#2SelfsourcingLearningoutcome#3PrototypingLearningoutcome#4OutsourcingLearningoutcome#56-9INSOURCINGANDTHESDLCSystemsdevelopmentlifecycle(SDLC)-astructuredstep-by-stepapproachfordevelopinginformationsystems7distinctphases,eachwithwell-definedactivitiesAlsocalledawaterfallmethodology,anapproachinwhicheachphaseoftheSDLCisfollowedbyanother,fromplanningthroughimplementation6-10SDLCPhases&MajorActivities6-11SDLCasaWaterfallMethodology6-12Phase1:PlanningPlanningphase-createasolidplanfordevelopingyourinformationsystemThreeprimaryplanningactivities:DefinethesystemtobedevelopedYoucan’tbuildeverysystem,soyoumakechoicesbasedonyourorganization’spriorities,whichmaybeexpressedascriticalsuccessfactorsCriticalsuccessfactor(CSF)-afactorsimplycriticaltoyourorganization’ssuccess6-13Phase1:PlanningSettheprojectscopeProjectscope-clearlydefinesthehigh-levelsystemrequirementsScopecreep-occurswhenthescopeoftheprojectincreasesFeaturecreep-occurswhendevelopersaddextrafeaturesthatwerenotpartoftheinitialrequirementsProjectscopedocument-awrittendefinitionoftheprojectscopeandisusuallynolongerthanaparagraph6-14Phase1:PlanningDeveloptheprojectplanincludingtasks,resources,andtimeframesProjectplan-definesthewhat,when,andwhoquestionsofsystemdevelopmentProjectmanager-anindividualwhoisanexpertinprojectplanningandmanagement,definesanddevelopstheprojectplanandtrackstheplantoensureallkeyprojectmilestonesarecompletedontimeProjectmilestones-representkeydatesforwhichyouneedacertaingroupofactivitiesperformed6-15Phase1:PlanningSampleProjectPlan6-16Phase2:AnalysisAnalysisphase-involvesendusersandITspecialistsworkingtogethertogather,understand,anddocumentthebusinessrequirementsfortheproposedsystem6-17Phase2:AnalysisTwoprimaryanalysisactivities:GatherthebusinessrequirementsBusinessrequirements-thedetailedsetofknowledgeworkerrequeststhatthesystemmustmeetinordertobesuccessfulBusinessrequirementsaddressthe“why”and“what”ofyourdevelopmentactivitiesJointapplicationdevelopment(JAD)-knowledgeworkersandITspecialistsmeet,sometimesforseveraldays,todefineorreviewthebusinessrequirementsforthesystem6-18Phase2:AnalysisPrioritizetherequirementsRequirementsdefinitiondocument–prioritizesthebusinessrequirementsandplacestheminaformalcomprehensivedocumentAgain,youprobablycan’tdoeverything,soprioritizingisimportantUserssignoffonthisdocumentwhichclearlysetsthescopefortheproject6-19Phase2:AnalysisTaketimeduringanalysistogetthebusinessrequirementscorrect.Ifyoufinderrors,fixthemimmediately.ThecosttofixanerrorintheearlystagesoftheSDLCisrelativelysmall.Inlaterstages,thecostishuge.6-20Phase3:DesignDesignphase-buildatechnicalblueprintofhowtheproposedsystemwillworkTwoprimarydesignactivities:DesignthetechnicalarchitectureTechnicalarchitecture-definesthehardware,software,andtelecommunicationsequipmentrequiredtorunthesystem6-21Phase3:DesignDesignsystemmodelsThisincludesGUIscreensthatuserswillinterfacewith,databasedesigns(seeXLM/C),reportformats,softwaresteps,etcStartingwithdesign,youtakeonlessofanactiveparticipationroleandactmoreasa“qualitycontrol”function,ensuringthattheITpeoplearedesigningasystemtomeetyourneeds6-22Phase4:DevelopmentDevelopmentphase-takeallofyourdetaileddesigndocumentsfromthedesignphaseandtransformthemintoanactualsystemTwoprimarydevelopmentactivities:BuildthetechnicalarchitectureBuildthedatabaseandprogramsBothoftheseactivitiesaremostlyperformedbyITspecialists6-23Phase5:TestingTestingphase-verifiesthatthesystemworksandmeetsallofthebusinessrequirementsdefinedintheanalysisphaseTwoprimarytestingactivities:WritethetestconditionsTestconditions-thedetailedstepsthesystemmustperformalongwiththeexpectedresultsofeachstep6-24Phase5:TestingPerformthetestingofthesystemUnittesting–testsindividualunitsofcodeSystemtesting–verifiesthattheunitsofcodefunctioncorrectlywhenintegratedIntegrationtesting–verifiesthatseparatesystemsworktogetherUseracceptancetesting(UAT)–determinesifthesystemsatisfiesthebusinessrequirements6-25Phase6:ImplementationImplementationphase-distributethesystemtoalloftheknowledgeworkersandtheybeginusingthesystemtoperformtheireverydayjobsTwoprimaryimplementationactivitiesWritedetaileduserdocumentationUserdocumentation-highlightshowtousethesystem6-26Phase6:ImplementationProvidetrainingforthesystemusersOnlinetraining-runsovertheInternetoroffaCD-ROMWorkshoptraining-isheldinaclassroomenvironmentandleadbyaninstructor6-27Phase6:ImplementationChoosetherightimplementationmethodParallelimplementation–useboththeoldandnewsystemsimultaneouslyPlungeimplementation–discardtheoldsystemcompletelyandusethenewPilotimplementation–startwithsmallgroupsofpeopleonthenewsystemandgraduallyaddmoreusersPhasedimplementation–implementthenewsysteminphases6-28Phase7:MaintenanceMaintenancephase-monitorandsupportthenewsystemtoensureitcontinuestomeetthebusinessgoalsTwoprimarymaintenanceactivities:BuildahelpdesktosupportthesystemusersHelpdesk-agroupofpeoplewhorespondstoknowledgeworkers’questionsProvideanenvironmenttosupportsystemchanges6-29COMPONENT-BASEDDEVELOPMENTTheSDLCfocusesonlyontheprojectathandComponent-baseddevelopment(CBD)–focusesonbuildingsmallself-containedblocksofcode(components)thatcanbereusedacrossavarietyofapplicationsCBDfocusesonUsingalready-developedcomponentstobuildsystemsquicklyBuildingnewcomponentsasneededthatcanbeusedinallfuturesystems6-30Component-BasedDevelopmentMethodologiesRapidapplicationdevelopment(RAD)Extremeprogramming(XP)Agilemethodology6-31RapidApplicationDevelopment(RAD)Rapidapplicationdevelopment(RAD)(alsocalledrapidprototyping)-emphasizesextensiveuserinvolvementintherapidandevolutionaryconstructionofworkingprototypesofasystemtoacceleratethesystemsdevelopmentprocessPrototypesaremodelsofthesoftwarecomponentsThedevelopmentteamcontinuallydesigns,develops,andteststhecomponentprototypesuntiltheyarefinished6-32RapidApplicationDevelopment(RAD)BuildnewsoftwarecomponentsUsealready-existingsoftwarecomponents6-33ExtremeProgramming(XP)Extremeprogramming(XP)-breaksaprojectintotinyphasesanddeveloperscannotcontinueontothenextphaseuntilthefirstphaseiscomplete6-34AgileMethodologyAgilemethodology-aformofXP,aimsforcustomersatisfactionthroughearlyandcontinuousdeliveryofusefulsoftwarecomponents6-35SoA–AnArchitecturePerspectiveService-orientedarchitecture(SoA)–perspectivethatfocusesonthedevelopment,use,andreuseofsmallself-containedblocksofcode(calledservices)tomeetallapplicationsoftwareneedsAllCBDmethodologiesadheretoanSoAServicesarethesameascomponents,whicharethesameassmallself-containedblocksofcodeMoreinChapter76-36SELFSOURCINGSelfsourcing(end-userdevelopment)–thedevelopmentandsupportofITsystemsbyenduserswithlittleornohelpfromITspecialistsDo-it-yourselfsystemsdevelopmentapproachCanrelieveITspecialistsoftheburdenofdevelopingmanysmallersystems6-37SelfsourcingApproachIssimilartotraditionalSDLCBigexceptionisthatdesign,development,testing,andimplementationarereplacedbytheprocessofprototypingPrototypingistheprocessofbuildingmodels,and–inthiscase–continuallyrefiningthosemodelsuntiltheybecomethefinalsystem6-38SelfsourcingApproach6-39SelfsourcingAdvantagesImprovesrequirementsdeterminationIncreasesenduserparticipationandsenseofownershipIncreasesspeedofsystemsdevelopmentReducesinvisiblebacklogInvisiblebacklog–listofallsystemsthatanorganizationneedstodevelopbut–becauseoftheprioritizationofsystemsdevelopmentneeds–nevergetfundedbecauseofthelackoforganizationalresources6-40SelfsourcingDisadvantagesInadequateenduserexpertiseleadstoinadequatelydevelopedsystemsLackoforganizationalfocuscreates“privatized”ITsystemsInsufficientanalysisofdesignalternativesleadstosubparITsystemsLackofdocumentationandexternalsupportleadstoshort-livedsystems6-41TheRightToolfortheJobEndusersmusthavedevelopmenttoolsthat:AreeasytouseSupportmultipleplatformsOfferlowcostofownershipSupportawiderangeofdatatypes6-42PROTOTYPINGPrototype–amodelofaproposedproduct,service,orsystemPrototyping-theprocessofbuildingamodelthatdemonstratesthefeaturesofaproposedproduct,service,orsystemProof-of-conceptprototype-usedtoprovethetechnicalfeasibilityofaproposedsystemSellingprototype-usedtoconvincepeopleoftheworthofaproposedsystem6-43ThePrototypingProcessTheprototypingprocessinvolvesfoursteps:IdentifybasicrequirementsDevelopinitialprototypeUserreviewReviseandenhancetheprototype6-44ThePrototypingProcess6-45AdvantagesofPrototypingEncouragesactiveuserparticipation

HelpsresolvediscrepanciesamongusersGivesusersafeelforthefinalsystemHelpsdeterminetechnicalfeasibility

Helpsselltheideaofaproposedsystem

6-46DisadvantagesofPrototypingLeadspeopletobelievethefinalsystemwillfollowGivesnoindicationofperformanceunderoperationalconditionsLeadstheprojectteamtoforgopropertestinganddocumentation

6-47OUTSOURCINGOutsourcing–thedelegationofspecifiedworktoathirdpartyforaspecifiedlengthoftime,ataspecifiedcost,andataspecifiedlevelofserviceThethird“who”optionofsystemsdevelopment,afterinsourcingandselfsourcing6-48OUTSOURCINGThemainreasonsbehindtherapidgrowthoftheoutsourcingindustryincludethefollowing:GlobalizationTheInternetGrowingeconomyandlowunemploymentrateTechnologyDeregulation6-49OutsourcingOptionsIToutsourcingforsoftwaredevelopmentcantakeoneoffourforms:PurchaseexistingsoftwarePurchaseexistingsoftwareandpaythepublishertomakecertainmodificationsPurchaseexistingsoftwareandpaythepublisherfortherighttomakemodificationsyourselfOutsourcethedevelopmentofanentirelynewanduniquesystemforwhichnosoftwareexists6-50OutsourcingOptions6-51OutsourcingProcessLikeselfsourcing,theselfsourcingprocesslookssimilartothetraditionalSDLCBigexceptionhereisthatyou“outsource”mostoftheworktoanothercompany6-52OutsourcingProcessWhenoutsourcing,you’lldeveloptwovitallyimportantdocuments–arequestforproposalandaservicelevelagreement6-53Outsourcing–RFPRequestforproposal(RFP)–formaldocumentthatdescribesinexcruciatingdetailyourlogicalrequirementsforaproposedsystemandinvitesoutsourcingorganizations(vendors)tosubmitbidsforitsdevelopmentInoutsourcing,youmus