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1、2 Systems Analysis and Design in a Changing World, Fourth Edition12Learning ObjectivesuExplain the purpose and various phases of the systems development life cycle (SDLC)uExplain when to use an adaptive approach to the SDLC in place of a more predictive traditional SDLCuExplain the differences betwe
2、en a model, a tool, a technique, and a methodologyuDescribe the two overall approaches used to develop information systems: the traditional method and the object-oriented method22Learning Objectives (continued)uDescribe some of the variations of the systems development life cycle (SDLC)uDescribe the
3、 key features of current trends in systems development: the Unified Process (UP), Extreme Programming (XP), Agile Modeling, and ScrumuExplain how automated tools are used in system development敏捷建模32OverviewuSystem development projectlPlanned undertaking with fixed beginning and endlProduces desired
4、result or product lCan be a large job with thousands of hours of effort or a small one-month projectuSuccessful development projectlProvides a detailed plan to followlOrganized, methodical sequence of tasks and activitieslProduces reliable, robust, and efficient system42The Systems Development Lifec
5、ycle (SDLC)uSystems development life cycle (SDLC)lProvides overall framework for managing systems development processuTwo main approaches to SDLClPredictive approach assumes project can be planned out in advancelAdaptive approach more flexible, assumes project cannot be planned out in advanceuAll pr
6、ojects use some variation of SDLC52Choosing the Predictive vs. Adaptive Approach to the SDLC (Figure 2-1)62Traditional Predictive Approach to the SDLCuProject planning initiate, ensure feasibility, plan schedule, obtain approval for projectuAnalysis understand business needs and processing requireme
7、ntsuDesign define solution system based on requirements and analysis decisionsuImplementation construct, test, train users, and install new systemuSupport keep system running and improve理解待解决的业务及定义业务需求开发程序结构和算法72Information System Development Phases82SDLC and Problem SolvinguSimilar to problem-solvi
8、ng approach in Chapter 1lOrganization recognizes problem (project planning)lProject team investigates, understands problem and solution requirements (analysis)lSolution is specified in detail (design)lSystem that solves problem is built and installed (implementation)lSystem used, maintained, and enh
9、anced to continue to provide intended benefits (support)92“Waterfall” Approach to the SDLC1021. 瀑布模型 ( (Waterfall Model) )可行性研究与计划可行性研究与计划需求分析需求分析设计设计编码编码运行维护运行维护测试测试定义定义阶段阶段开开发发阶阶段段维护阶段维护阶段112Modified Waterfall Approachwith Overlapping Phases (Figure 2-5)122Newer Adaptive Approaches to the SDLCuBas
10、ed on spiral modellProject cycles through development activities over and over until project is completelPrototype created by end of each cyclelFocuses on mitigating riskuIteration Work activities are repeated lEach iteration refines previous resultlApproach assumes no one gets it right the first ti
11、melThere are a series of mini projects for each iteration132The Spiral Life Cycle Model (Figure 2-6)142Iteration of System Development Activities(Figure 2-7)152采用原型模型的软件生存周期分析定义分析定义系统需求系统需求生成生成原型原型系统系统设计设计程序程序设计设计编码编码测试测试运运 行行和维护和维护原型化原型化含原型化的含原型化的软件生存期软件生存期162建造建造/ /修改修改 原型原型用户测试用户测试运行原型运行原型 听取用听取用
12、 户意见户意见原型范型原型范型原型范型原型范型172螺旋模型风险风险分析分析工程工程实施实施用户通信用户通信用户用户评估评估产品维护项目产品维护项目产品维护项目产品维护项目产品增强项目产品增强项目产品增强项目产品增强项目新产品开发项目新产品开发项目新产品开发项目新产品开发项目概念开发项目概念开发项目概念开发项目概念开发项目计划计划计划计划建造及发布建造及发布建造及发布建造及发布182Activities of Each SDLC PhaseuPredictive or adaptive approach use SDLCuActivities of each “phase” are simil
13、aruPhases are not always sequentialuPhases can overlapuActivities across phases can be done within an iteration192Activities of Planning Phase of SDLCuDefine business problem and scopeuProduce detailed project schedule uConfirm project feasibility lEconomic, organizational, technical, resource, and
14、scheduleuStaff the project (resource management)uLaunch project official announcement准确定义业务及解决方案的范围202Activities of Analysis Phase of SDLCuGather information to learn problem domainuDefine system requirementsuBuild prototypes for discovery of requirementsuPrioritize requirementsuGenerate and evaluat
15、e alternativesuReview recommendations with management了解客户并详述需求212Activities of Design Phase of SDLCuDesign and integrate the networkuDesign the application architectureuDesign the user interfacesuDesign the system interfacesuDesign and integrate the databaseuPrototype for design detailsuDesign and i
16、ntegrate system controls222Activities of Implementation Phase of SDLCuConstruct software componentsuVerify and test uConvert datauTrain users and document the systemuInstall the system232Activities of Support Phase of SDLCuMaintain systemlSmall patches, repairs, and updatesuEnhance systemlSmall upgrades or enhancements to expand system capabilitieslLarger enhancements may require separate development projectuSupport userslHelp desk and/or support team242Methodologies and ModelsuMethodologieslCom
