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Use Case analysis and design, , wixom, and roth. © Copyright 2015 John Wiley & Sons, Inc. 1Learning Objectivesq Explain the purpose of use cases in the analysis phase of. the SDLCq Describe the various parts of a use case and the purpose. of each partq Describe how use cases contribute to the functional. requirementsq Describe how use cases inform the development of test. plansq Explain the process used to create a use case. © Copyright 2015 John Wiley & Sons, Inc. 2What is a Use Case?.Understanding the purpose of this tool. © Copyright 2015 John Wiley & Sons, Inc. 3Role of Use Casesq Use cases express and clarify user requirementsq Purpose - define the expected interaction between user. and systemq Use that interaction to more fully describe functional. Used extensively in the analysis phase. Often a part of. user interviews or JAD sessionsq Text-based use cases are easy for the users to. understandq Flow easily into the creation of process models and the. © Copyright 2015 John Wiley & Sons, Inc. 4Use Casesq Represents how a system interacts with its. Illustrates the activities that are performed by the. users and the system’s responsesq Activities produce some output resultq Each use case describes how an external user. triggers an event to which the system must. respondq © Copyright 2015 John Wiley & Sons, Inc. 5Use Case and formats. © Copyright 2015 John Wiley & Sons, Inc. 6Elements of a Use Caseq Each use case has a name and number, and brief. descriptionq The priority may be assigned to indicate the relative. significanceq The actor refers to a person, another system, or a. hardware device that interacts with the system to. achieve a useful goalq The trigger for the use case – the event that causes. the use case to beginq Events triggers can be external or temporal. © Copyright 2015 John Wiley & Sons, Inc. 7Use Figure 4-1. From. Casual Format . © Copyright 2015 John Wiley & Sons, Inc. The major steps that. are performed to. execute the response to. the event. © Copyright 2015 John Wiley & Sons, Inc. Error conditions. encountered while. performing use case. stepso NOT normal branches. in decision logico Lead to an. unsuccessful result © Copyright 2015 John Wiley & Sons, Inc. 10Use Uses cases often. performed in sequenceo No single use case. should be too largeo Important to define. initial and ending. states © Copyright 2015 John Wiley & Sons, Inc. Preconditions define. what must be complete. before beginning this. use caseo Postconditions define. what is complete when. this use case ends © Copyright 2015 John Wiley & Sons, Inc. 12Fully-Dressed Use Case Formatq Very thorough, detailed, and highly structuredq Adds new sections, including,. o Alternative courses. o Inputs and outputs for steps. o Summary inputs and outputsqSee Figure 4-3 for example. © Copyright 2015 John Wiley & Sons, Inc. 13Fully-Dressed Use Case Format,.con’tq Use this format when:. o Users are not closely engaged with development. team. o Project has high complexity and high risk. o Test cases need to be fully described. o Remote collaborating teams need detailed,. shared understanding of user needs © Copyright 2015 John Wiley & Sons, Inc. 14Use Case Practical Tipsq Use gradual refinementq Concentrate on describing the user’s. objectives with the system completely a