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1、Requirements Management with Use Cases,Module 4 Understanding Stakeholder Needs,Course Outline,0-About This Course1-Best Practices of Software Engineering 2-Introduction to RMUC3-Analyzing the Problem4-Understanding Stakeholder Needs5-Defining the System6-Managing the Scope of the System7-Refining t
2、he System Definition8-Managing Changing Requirements9-Requirements Across the Product Lifecycle,Understanding Stakeholder Needs-Overview,Problem,Solution Space,Problem Space,Needs,Features,SoftwareRequirements,I need,What Are Sources for Our Requirements?,Customer,Users,Problem Domain,Domain Experts
3、Industry AnalystsSite VisitsCompetitive info.,Bug ReportsChange Requests,Requirement SpecsBusiness PlansPersonal GoalsBusiness Models,Analyst,Partners,Moore,1991,Time,INNOVATORS Technical Influence No Money Discontinuous innovation Company specific,EARLY ADOPTERS Have money Strong Influence Specific
4、 features,EARLY MAJORITY Pragmatists Mission critical systems Reliability Whole product solutions,LATE MAJORITY Conservatives Price sensitive Simplify Commodity Demanding,LAGGARDS Skeptics Price,0%,5%,10%,15%,20%,25%,30%,35%,What Are The Characteristics of Our Customers?,%of Target Domain Customers,
5、Technology AdoptionProfile,(the lifecycle of the technology),What Problems Might Be Encountered?,Stakeholders know what they want but may not be able to articulate it.Stakeholders may not know what they want.Stakeholders think they know what they want until you give them what they said they wanted.A
6、nalysts think they understand user problems better than users.Everybody believes everybody else is politically motivated.,What Does This Process Look Like?,Customer,Development,Requirements Spec,Approved!,Rejected,Reworked Spec,Rejected,Reworked again,Ad hoc requirements,Techniques for Eliciting Sta
7、keholder Needs,Requirements WorkshopBrainstorming&Idea ReductionUse CasesInterviewsQuestionnairesRole PlayingBusiness ModelingReviewing Customer Requirement Specifications,Requirements Workshops,Accelerate the Elicitation ProcessGathers all stakeholders together for an intensive,focused periodFacili
8、tator runs the meetingEveryone gets their say Results immediately availableProvide a framework for applying the other elicitation techniques we will be discussing,Workshops:Planning and Executing,Sell the workshopEstablish teamHandle logisticsIssue warm-up materialPrepare agenda,FacilitateKeep on tr
9、ackRecord findingsSummarize conclusions,Synthesize findingsCondense info,Present to customerDetermine next steps,Workshops:Tricks of the Trade,Workshop Tickets,Rules for Brainstorming,Brainstorming,Clearly state the objective of the sessionGenerate as many ideas as possibleLet your imagination soarD
10、o not allow criticism or debateMutate and combine ideas,Brainstorming Exercise,1.PrepareStack of Post-Its for each participantLarge markers for all2.Gather IdeasWrite it down Shout it outFacilitator posts on board3.Prune IdeasCombine like ideasEliminate outrageous ideas4.Organize IdeasMove the cards
11、 aroundCould organize by FURPS,Discard redundant and outrageous ideasStore“needs more development”ideasBlend ideasPrioritize those that remainVoteSingle voteCumulative votingBuy featuresApply evaluation criteriaNon-weightedWeighted,Brainstorming:Idea Reduction,RU“bucks”,Use-Case Model,How Can a Use-
12、Case Model Help Elicit Needs?,Discuss with customer what the system will doIdentify who will interact with the systemIdentify what interfaces the system should haveHelp verify that no requirements are missingVerify that developers understand requirements,A use casedefines a sequence of actionsperfor
13、med by a system that yields an observable result of value to an actor,What Is a Use Case?Key Words and Phrases,A use case describes a set(class)of possible executions of the systemA specific execution(instance)of a use case is a scenarioWork on the class level to identify and describe the use caseSe
14、t of atomic activities,decisions,and requestsMay be performed fully or not at allStarted by actor,What Is a Use Case?Key Words and Phrases,A Simple Phone System,Define System Boundaries and Functions,A model of what the system does and who it does it for,Useful Questions in Identifying Use Cases,Wha
15、t are the primary tasks the actor wants the system to perform?Will the actor create,store,change,remove,or read data in the system?Will the actor need to inform the system about sudden,external changes?Does the actor need to be informed about certain occurrences in the system?Will the actor perform
16、a system startup or termination?,Exercise:Identify Possible Use Cases,Our System,A Use-Case Model Diagram,A model of what the system is supposed to do(use cases),and the systems surroundings(actors).,A Recycling Machine,Interviews,A direct technique that can be used in both problem analysis and requ
17、irements elicitationDesigned to gain an understanding of real problems and potential solutions from the perspectives of the users,customers,and other stakeholders,Gause&Weinberg,1989,Interviews:The Context-Free Question,The context-free question is a high-level,abstract question that can be posed ea
18、rly in a project to obtain information about global properties of the users problem and potential solutions.Context-free questions:Are always appropriate Help you understand stakeholder perspectives Are not biased with solutions knowledge,Gause&Weinberg,1989,Interviews:Context-Free User Questions,Wh
19、o is the customer?Who is the user?Are their needs different?What are their backgrounds,capabilities,environments?Use as input when defining actors for Use Cases,Gause&Weinberg,1989,Interviews:Context-Free Process Questions,What is the problem?What is the reason for wanting to solve this problem?Are
20、there other reasons for wanting to solve this problem?What is the value of a successful solution?How do you solve the problem now?What is the trade-off between time and value?Where else can the solution to this problem be found?,Gause&Weinberg,1989,Interviews:Context-Free Product Questions,What prob
21、lem does this product solve?What business problems could this product create?What hazards could exist for the user?What environment will the product encounter?What are your expectations for usability?What are your expectations for reliability?What performance/precision is required?,Gause&Weinberg,19
22、89,Interviews:Context-Free Meta-questions,Am I asking too many questions?Do my questions seem relevant?Are you the right person to answer these questions?Are your answers requirements?Can I ask more questions later?Would you be willing to participate in a requirements review?Is there anything else I
23、 should be asking you?,Interviews:Non-Context-Free Examples,Leading questionsYou need a larger screen,dont you?Self answering questionsAre fifty items about right?Controlling statementsCan we get back to my questions?Too long-too complexI have a three part question,.,What are better questions to ask
24、?,Interviews:Caveats,Dont ask people to describe things they dont usually describe.Assumes that users can describe complex activitiesExample:tying your shoelaceIn general,people can do many things they cannot describeEmpirical evidence-poor correlationAsk open-ended questionsAvoid questions that beg
25、in with“Why?”Can provoke a defensive postureDont expect simple answersDont rush the interviewee for answersListen,listen,listen!,Template For A Generic Interview:Handout,TP:Generic Interview Template,1994 by Alan M.Davis,Questionnaires,Widely usedAppear scientific because of statistical analysisAppl
26、icability to broad markets where questions are well definedAssumptionsRelevant questions can be decided in advancePhrased so reader hears in intended waySuppresses much that is good about analysisCan be powerful,but not a substitute for an interview,Course Feedback Questionnaire:Handout,Tools and Te
27、chniquesScripted walkthroughsScenario analysisClass Responsibility Collaboration(CRC)CardsHave the analyst play the role of user or customer to gain real insights into the problem domainHave the customer play the role of a user to understand the problems they may face,Role Playing,What About Busines
28、s Modeling?,From a business perspective,a business model may be used to:Understand the organizationVisualize the organization and its processesFind ways to make the organization more efficientRe-engineer the organizationProvide proof that the information technology adds value,Business Models Provide
29、 Input to Systems,What should business models show?Business ProcessesOrganizational structureRoles and responsibilities,Products Deliveries Events,Reviewing Customer Requirement Specs,How to identify requirements In general,ignore:IntroductionsGeneral system descriptionsGlossary of terms Other expla
30、natory informationFind application behaviors or behavioral attributes and select and label uniquelyKeep a list of all identified issues and assumptions-verify with the customer or userIf you dont know if something is a requirement,ask the customer!,Exercise:Reviewing Requirements Specs,Identify and
31、itemize RequirementsReview the 2001 Elevator SRS that has been given to you by your customer Mark and number each requirement you find How many requirements did you find?,Requirements Spec.at end of module,Eliciting Needs:Which Tools to Use?,Developer Experience,Customer/UserExperience,Low,Hi,Low,Hi
32、,“Fuzzy problem”,“Catch Up”,“Mature”,“Selling/Teaching”,Adapted from Alan Davis,Requirements WorkshopBrainstormingUse CasesInterviewsQuestionnairesRole PlayingBusiness ModelingRequirement Reviews,Which of these tools might you use for each quadrant of the graph?,RUP Workflow Detail:Understanding Nee
33、ds,RUP Workflow Detail:Understanding Needs,Review:Understanding Stakeholder Needs,1.What are some of the problems encountered in trying to understand user needs?2.What is the basis of the“context-free”question?What are four categories of“context-free”questions?Give example questions in each category3.What are some elicitation techniques you believe can be helpful in understanding your users needs?List some advantages and drawbacks of each4.How are use cases helpful in eliciting user needs?5.How would you plan a review of a customer-generated requirement spec?,
