Software System EngineeringSlide 2Slide 3Use Case Modeling: Core ElementsUse Case Modeling: Core Relationships (1)Use Case Modeling: Core Relationships (2)Use Case Diagram TourWhen to model use casesUse Case Modeling TipsActors (1)Actors (2)Use Cases (1)Use Cases (2)Use Cases (3)Use Case Relationships (1)Use Case Relationships (2)Use Case Relationships (3)Use Case Relationships (4)Use Case Relationships (5)Use Case Relationships (6)Use Case Relationships (7)Use Case Relationships (8)Use Case ModelWhat is use case modeling?Use Case Diagram (1)Use Case Diagram (2)Use Case Diagram (3)Use Case Diagram (4)Use Case Diagram (5)Use Case Diagram (6)Use Case Diagram (7)Slide 32Use Case Diagram (8)The Use Case ModelUse Case Template & Example: Change FlightMy Use Case TemplateCase Study 1: Library SystemFirst Step!Documenting Use CasesActorsUse CasesUse Case DescriptionUse Case Diagram for the first iterationWhat Requirements would an ideal system satisfy?Slide 45Use Cases for the libraryCase Study 2: University RegistrationSlide 48Slide 49Maintain Curriculum: Flow of Events (description)Slide 51Uses and Extends Use Case RelationshipsPossible Problems with Use CasesCautionsSample Use Case from Philips Project (1)Sample Use Case from Philips Project (2)Sample Use Case from Philips Project (3)Sample Use Case from Philips Project (4)Sample Use Case from Philips Project (5)Sample Use Case from Philips Project (6)Sample Use Case from Philips Project (7)Slide 62Slide 63Slide 64Slide 65Slide 66Slide 67Slide 68Discussion QuestionsQuestions for the Next LectureTasks for Next Lecture© M.E. Fayad 2000 -- 2006SJSU -- CmpESoftware System Engineering Dr. M.E. Fayad, ProfessorComputer Engineering Department, Room #283I College of EngineeringSan José State UniversityOne Washington SquareSan José, CA 95192-0180 http://www.engr.sjsu.edu/~fayad© M.E. Fayad 2000 -- 2006SJSU – CmpE M.E. Fayad L3-3-S2 UC Diagrams2Lesson 7:Use Case Diagrams© M.E. Fayad 2000 -- 2006SJSU – CmpE M.E. Fayad L3-3-S3 UC Diagrams Lesson ObjectivesObjectives3 Overview of Previous Lecture  Use Case Models and Diagrams Notation Discuss the following: – What is use case modeling?– Use Case Modeling -- Core concepts– Use Case Diagram tour– When to model use cases– Use Case Modeling tips– Use Case Templates– Examples: Library & University Registration© M.E. Fayad 2000 -- 2006SJSU – CmpE M.E. Fayad L3-3-S4 UC DiagramsUse Case Modeling: Core ElementsUse Case Modeling: Core Elements4Construct Description Syntax use case A sequence of actions, including variants, that a system (or other entity) can perform, interacting with actors of the system. actor A coherent set of roles that users of use cases play when interacting with these use cases. system boundary Represents the boundary between the physical system and the actors who interact with the physical system. U s e C a s e N a m eA c t o r N a m e© M.E. Fayad 2000 -- 2006SJSU – CmpE M.E. Fayad L3-3-S5 UC DiagramsUse Case Modeling: Core Relationships Use Case Modeling: Core Relationships (1)Construct Description Syntaxassociation The participation of an actor in a usecase. i.e., instance of an actor andinstances of a use case communicatewith each other.extend A relationship from an extension usecase to a base use case, specifyinghow the behavior for the extensionuse case can be inserted into thebehavior defined for the base usecase.generalization A taxonomic relationship between amore general use case and a morespecific use case.5<<extend>>© M.E. Fayad 2000 -- 2006SJSU – CmpE M.E. Fayad L3-3-S6 UC DiagramsUse Case Modeling: Core Relationships Use Case Modeling: Core Relationships (2)6Construct Description Syntaxinclude An relationship from a base use caseto an inclusion use case, specifyinghow the behavior for the inclusion usecase is inserted into the behaviordefined for the base use case.<<include>>Multiplicities are missing!© M.E. Fayad 2000 -- 2006SJSU – CmpE M.E. Fayad L3-3-S7 UC DiagramsShows use cases, actor and their relationshipsUse case internals can be specified by text and/or interaction diagramsKinds–use case diagram–use case description7Use Case Diagram Tour© M.E. Fayad 2000 -- 2006SJSU – CmpE M.E. Fayad L3-3-S8 UC DiagramsModel user requirements with use cases.Model test scenarios with use cases.If you are using a use-case driven method–start with use cases and derive your structural and behavioral models from it.If you are not using a use-case driven method–make sure that your use cases are consistent with your structural and behavioral models8When to model use cases© M.E. Fayad 2000 -- 2006SJSU – CmpE M.E. Fayad L3-3-S9 UC DiagramsMake sure that each use case describes a significant chunk of system usage that is understandable by both domain experts and programmersWhen defining use cases in text, use nouns and verbs accurately and consistently to help derive objects and messages for interaction diagramsFactor out common usages that are required by multiple use cases–If the usage is required use <<include>>–If the base use case is complete and the usage may be optional, consider use <<extend>>A use case diagram should–contain only use cases at the same level of abstraction–include only actors who are requiredLarge numbers of use cases should be organized into packages9Use Case Modeling Tips© M.E. Fayad 2000 -- 2006SJSU – CmpE M.E. Fayad L3-3-S10 UC Diagrams10Actors (1)An actor is someone or some thing that must interact with the system under developmentStudentRegistrar ProfessorBilling System© M.E. Fayad 2000 -- 2006SJSU – CmpE M.E. Fayad L3-3-S11 UC DiagramsAn actor represents a coherent set of roles that users of use cases play when interacting with the use casesTypically, an actor represents a role that a human, a hardware device, or even another system plays with a system11Actors (2)© M.E. Fayad 2000 -- 2006SJSU – CmpE M.E. Fayad L3-3-S12 UC DiagramsA use case is a pattern of behavior the system exhibits–Each use case is a sequence of related transactions performed by an actor and the system in a dialogue –It describes what a system does but NOT how it does it12Use Cases (1)© M.E. Fayad 2000 -- 2006SJSU – CmpE M.E. Fayad L3-3-S13 UC DiagramsA use case is a