Kĩ thuật lập trình - Chapter 1: Introduction to systems analysis and design

Chapter 1:Introduction to SystemsAnalysis and DesignObjectivesUnderstand the fundamental systems development life cycle and its four phases.Understand the evolution of systems development methodologies.Be familiar with the Unified Process and its extensions.Be familiar with the different roles on the project team.Why Should We Care?Would you buy a car that only had a 28% chance of driving off the lot with no problems?Recent Significant IT FailuresCompanyYear OutcomeHudson Bay (Canada)2005Inventory system problems lead to $33.3 million loss.UK Inland Revenue2004/5$3.45 billion tax-credit overpayment caused by software errors.Avis Europe PLC (UK)2004Enterprise resource planning (ERP) system cancelled after $54.5 million spent.Ford Motor Co.2004Purchasing system abandoned after deployment costing approximately $400 MHewlett-Packard Co.2004ERP system problems contribute to $160 million loss.AT&T Wireless2004Customer relations management system upgrade problems lead to $100M lossSYSTEMS DEVELOPMENT LIFE CYCLESystems Development Life CyclePlanningAnalysisDesignImplementationSDLC: PlanningProject InitiationDevelop a system requestConduct a feasibility analysisProject ManagementDevelop work planStaff the projectControl and direct the projectWhy should we build this system?SDLC: AnalysisDevelop analysis strategyGather requirementsDevelop a system proposalWhat should the system do for us?Where and when will it be used?SDLC: DesignDevelop a design strategyDesign architecture and interfacesDevelop databases and file specificationsDevelop the program designHow will we build the system?SDLC: ImplementationConstruct systemInstall systemImplement a training plan for the usersEstablish a support planBuild the system!Putting the SDLC TogetherEach phase consists of steps that lead to specific deliverablesThe system evolves through gradual refinementOnce the system is implemented, it may go back into a planning phase for its next revision, a follow-on system, or maintenance releasesProcesses and DeliverablesSYSTEMS DEVELOPMENT METHODOLOGIESSystems Development MethodologiesA methodology is a formalized approach to implementing the SDLCWell-known methodologies include:Waterfall developmentParallel developmentV-modelRapid application developmentAgile developmentCategories of MethodologiesStructured DesignWaterfall DevelopmentParallel DevelopmentRapid Application DevelopmentPhasedPrototypingThrowaway PrototypingAgile DevelopmenteXtreme ProgrammingStructured Design 1Waterfall DevelopmentStructured Design 2Parallel DevelopmentRapid Application Development 1Phased DevelopmentRapid Application Development 2System PrototypingRapid Application Development 3Throwaway PrototypingAgile DevelopmentExtreme ProgrammingSelecting the Right MethodologyUsefulness forWaterfallParallelPhasedPrototypingThrowaway PrototypingExtreme ProgrammingUnclear user requirementsPoorPoorGoodExcellentExcellentExcellentUnfamiliar technologyPoorPoorGoodPoorExcellentPoorComplex systemsGoodGoodGoodPoorExcellentPoorReliable systemsGoodGoodGoodPoorExcellentGoodShort time schedulePoorGoodExcellentExcellentGoodExcellentSchedule visibilityPoorPoorExcellentExcellentGoodGoodObject-Oriented Analysis & DesignAttempt to balance emphasis on data and processUses Unified Modeling Language (UML) Characteristics of OOAD:Use-case DrivenArchitecture CentricIterative and IncrementalTHE UNIFIED PROCESSThe Unified ProcessA specific methodology that maps out when and how to use the various UML techniques for object-oriented analysis and designA two-dimensional process consisting of phases and flowsPhases describe how the system evolves over timeWorkflows are collections of tasks that occur throughout the lifecycle, but vary in intensityThe Unified ProcessUnified Process PhasesInceptionElaborationConstructionTransitionEngineering WorkflowsBusiness modelingRequirementsAnalysisDesignImplementationTestingDeploymentSupporting WorkflowsProject managementConfiguration and change managementEnvironmentOperations and support*Infrastructure management** Part of the enhanced unified processTHE UNIFIED MODELING LANGUAGEUnified Modeling LanguageProvides a common vocabulary of object-oriented terms and diagramming techniques rich enough to model any systems development project from analysis through implementationVersion 2.0 has 14 diagrams in 2major groups:Structure diagramsBehavior diagramsUML Structure DiagramsRepresent the data and static relationships in an information systemClassObjectPackageDeploymentComponentComposite structureUML Behavior DiagramsDepict the dynamic relationships among the instances or objects that represent the business information systemActivitySequenceCommunicationInteraction overviewTimingBehavior state machineProtocol state machine,Use-case diagramsPROJECT TEAM ROLES AND SKILLSProject Team SkillsProject team members are change agents who find ways to improve their organizationA broad range of skills is required, includingTechnicalBusinessAnalyticalInterpersonalManagementethicalProject Team RolesRoleResponsibilitiesBusiness AnalystAnalyzing the key business aspects of the systemIdentifying how the system will provide business valueDesigning the new business processes and policiesSystems AnalystIdentifying how technology can improve business processesDesigning the new business processesDesigning the information systemEnsuring the system conforms to IS standardsInfrastructure AnalystEnsuring the system conforms to infrastructure standardsIdentifying infrastructure changes required by the systemChange Management AnalystDeveloping and executing a change management planDeveloping and executing a user training planProject ManagerManaging the teamDeveloping and monitoring the project planAssigning resourcesServing as the primary point of contact for the projectSummaryAll systems development projects follow essentially the same process, called the system development life cycle (SDLC)System development methodologies are formalized approaches to implementing SDLCsObject-Oriented Systems Analysis and Design (OOSAD) uses a use-case-driven, architecture-centric, iterative, and incremental information systems development approachSummaryThe Unified Process is a two-dimensional systems development process described with a set of phases and workflowsThe Unified Modeling Language, or UML, is a standard set of diagramming techniquesThe project team needs a variety of skills