chap7需求分析-用例图

《chap7需求分析-用例图》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。

1、Chapter7MODELINGSYSTEMREQUIREMENTSWITHUSECASES使用用例建模系统需求AnIntroductiontoUse-CaseModeling简介Oneoftheprimarychallengesinasystemdesignprocessistheabilitytoelicit(提取)thecorrectandnecessarysystemrequirementsfromthestakeholdersandspecifytheminamannerunderstand

2、abletothemsothoserequirementscanbeverifiedandvalidated.系统开发过程的首要问题是正确地提取用户需求，并以用户能够理解的方式进行表达，以便他们他们能够核实并确认AnIntroductiontoUse-CaseModeling简介传统的建方法：DataandprocessmodelsPrototypesrequirementspecifications问题：设计者理解而用户不理解Leadstoscopecreep（范围蔓延）,schedulecreep（进

3、度蔓延）,costoverruns（成本超支）.User-CenteredDevelopmentandUse-CaseModeling以用户为中心的系统开发与用例建模User-CenteredDevelopmentUser-centereddevelopment–aprocessofsystemsdevelopmentbasedonunderstandingtheneedsofthestakeholdersandthereasonswhythesystemshouldbedeveloped.系统开发建立应

4、在理解用户需求之上Use-CaseModeling用例建模Use-casemodeling–theprocessofmodelingasystem’sfunctionsintermsof针对系统功能进行建模：businessevents：有哪些业务事件？whoinitiatedtheevents：谁发起了这些事件？andhowthesystemrespondstothoseevents：系统将如何响应这些事件？SampleUse-CaseModelDiagramBenefitsofUse-CaseMode

5、lingProvidesatoolforcapturingfunctionalrequirements(获取功能需求).Providesameansofcommunicatingwithusersandotherstakeholdersconcerningsystemfunctionalityinalanguagethatiseasilyunderstood.（便于沟通）Providesatoolforrequirementstraceability(需求跟踪).Providesaframeworkfor

6、drivingthesystemdevelopmentproject.（提供一个驱动系统开发项目的框架）SystemConceptsforUse-CaseModelingUse-casediagram–describeswhowillusethesystemandinwhatwaystheuserexpectstointeractwiththesystem.用例图——描述系统与外部系统或用户之间的交互图Use-casenarrative–atextualdescriptionofthebusinessev

7、entandhowtheuserwillinteractwiththesystemtoaccomplishthetask.用例说明——针对用例执行过程的文本说明Usecase–abehaviorallyrelatedsequenceofsteps(ascenario),bothautomatedandmanual,forthepurposeofcompletingasinglebusinesstask.用例——从外部使用者的角度描述系统功能，是一系列相关的操作步聚，共同完成单一的工作任务。SampleUs

8、e-CaseModelDiagramBasicUse-CaseSymbolsUsecase（用例）–subsetoftheoverallsystemfunctionalityRepresentedgraphicallybyahorizontalellipse（椭园）withthenameoftheusecaseappearingabove,below,orinsidetheellipse.Actor（参与者）–anythi