??????????????????????????stakeholders???????????Use Case?????????????写??效??????????????澹�???????????????
?????????????械???????????????
????1.Figure1.1 The "Hub-and-spoke" model of requirements?????UseCase??????????????
????2.Figure2.2 Striped trousers:Scenarios succeed or fail??????Scenarios?????????????????
????3.Figure5.1 Use case levels. The use case set reveals a hierarchy of goals --- the ever-unfolding story????????????????Summary Goals??User Goals??Subfunctions ?????????????????
????3.Figure5.2 Ask ‘‘Why‘‘ to shift levels?? ????????????Why??????How??
?????????????UseCase ?????
????Primary Actor
????Scope
????Level
????Preconditons
????Trigger
????Main Success Scenario
????Extensions
????Variations
????1?????????????????precondition???????????????????????????????????????????????????????????????????????????薪????????谩?
???????????????????????????????????????????????
??????????胃?????????????????锌??路??????瑁�?????????魏???????????????????????????????????????????????????????????“???????”???????????????“???”???????????“???????????”?????“?????????”??????“???”???????????
????2?????写???????????????????????????????????????????????????写???????????
???????纾�???????????????????????“???”????“????????”???????????
????3??小???????????????????????????????????????????????????????????????????????????????锟�??????????????????????????????????小????????/???????????
????4??????????success guarantee?????????????????????????????????些??????????????????????????????????贸??????????????锌??路????贸????????????????小?????????????小?????????????????些??????????妫�????????????????????????????????????
????5??????????????????????????????????????????/??????????????????????梅??????????????????“?????????????????????????????械????????”?????????????????????写???????????
????6???????????trigger??????????????????????