架构质量属性分析和评估

BriefDiscussiononNon-FunctionalRequirements(NFRs)TegegneMarewⓒKAISTSELAB2008Contents
Introduction
ClassificationofNFRs
TreatmentofNFRsNFRFrameworkandItsExtensionsArchitecturalTradeoffAnalysisMethodAttributeDrivenDesignAttributeDrivenDesign
ResearchIssues
Conclusion2ⓒKAISTSELAB2008Introduction
NFRsRequirementsofasystemthatarenotservicesHowwellasystemdeliverstheservicesNOTwhatthesystemdeliversHighlysubjective•User/developer/otherstakeholdersdecidehowwelltheyare•User/developer/otherstakeholdersdecidehowwelltheyaresatisfied–UnlikeFRswhichwecanobjectivelydeterminetheirimplementation•SomesayFRsarehardgoalsandNFRsaresoftgoals–FRsaresatisfiedwhereasNFRsaresatisficed(AItermtodescribesubjectivefulfillment)Alsoknownasqualityattributes(QA)PeculiarPropertiesofNFRs
SubjectiveNoteasytoanswerthequestion:“IsthisNFRfullyimplemented?”
AmbiguousNoteasytoanswerthequestion:“Whatisthedifferencebetweenmaintainabilityandmodifiability?”
NotequallyimportantSecurityforanuclearplantsoftwareismoreimportantthanSecurityforanuclearplantsoftwareismoreimportantthaninteroperability
AffecteachotherTheneedtosatisfyaccuracymaycomeatthecostofperformance
AffectFunctionalModelToimprovemaintainability,wemayredesignthefunctionalmodeltoreducecoupling
etcClassification
VariousproposedschemesExternalvsInternal•User-concernsVstechnical-criteriaPartialTableshowingPartialTableshowingrelationshipbetweenfactorsandcriteriaperformance:relatestohowthesystemrunsdesign:relatestohowthesystemisdesignedadaptation:relatestohowthesystemisported/modifiedClassification
Variousproposedschemes(cont’d)ProductVsProcess•Product:howthesystembehaves–Functionality–Usability–Efficiency–Etc•Process:theproductionquality–Cost–Schedule–Useofstandards–EtcClassification
Variousproposedschemes(cont’d)ISO9126•1)Functionality–suitability,security,compliance,accuracyandinteroperability•2)Reliability–maturity,recoverabilityandfaulttolerance–maturity,recoverabilityandfaulttolerance•3)Usability–learnabilityandoperability•4)Efficiency–resourceandtime•5)Maintainability–stability,changeabilityandtestability•6)Portability–instabilityandadaptabilityClassification
Variousproposedschemes(cont’d)Problemswithalltheschemessofar•StillmanyareleftuncategorizedInfact,thesedaysclassifyingNFRsisrarelyaresearchtopic.TheneedtoclassifycamefrombecauseresearchersTheneedtoclassifycamefrombecauseresearchersassumed•ItcouldhelpthemunderstandNFRsbetter(conceptually)•ItcouldhelpthemtreatNFRsinthesamegroupsimilarly…Sofar,littlesuccessonbothfrontsNFRFramework
Chunget.al,1989-99TreatNFRsassoftgoalsthatneedtobesatisficied•Softgoal–cannotbeabsolutelyfulfilled•Satsficing–satisfyingarequirementinavarietyofdegreewithoutnecessarilyoptimizing.–e.g..Somewhat,negatively,positively,verypositivelyConsistsof•SIG(SoftgoalInterdependencyGraph)•CataloguesforeachNFRNFRFrameworkSymbolMeaningSoftgoal:symbolizesNFR;thetopicistheNFRandtheparameteristheentity(class,subsystem,etc)theNFRisappliedtoHardgoal:operationalization,anapproachthatimplementsanNFRtopic[parameter]SIGsymbols“AND”Decomposition:Aparentissatisficedifallchildrenaresatisficed.“OR”Decompositon:Aparentissatisficedifoneofthechildrenaresatisficed..!Criticalnode:thisnodeisveryimportant+,-,++,--Contributionsofonenodetoanother:positive,negative,verypositive,verynegativeNFRFrameworkSampleSIGSampleSIGSampleSIGSampleSIGNFRFramework
CatalogueSortHierarchyMethods•HowtoimplementeachNFRInterdependency•WhoaffectswhoNFRFramework
DiscussionPros•SystematicmanagementofNFRs•Easyvisualizationofinteraction•Qualitative–ExpertknowledgeusedConsCons•ExclusivelyaboutNFRs•Noquantitativeanalysis–Difficulttoautomate,verysubjective•NeedsextensivecatalogabouteachNFRExtensionsofNFRFramework
NFRfromelicitationtoconceptualmodels(Cysenrios,TSE2004)IntegratesNFRsintoFRsmodeling•NeedstouseLEL(LexiconExtendedLanguage)–BasicvocabularytodescribeforbothFRandNFRs•Highlyautomated•HighlyautomatedExtensionsofNFRFrameworkOverviewofIntegratingNFRwithFROverviewofIntegratingNFRwithFROverviewofIntegratingNFRwithFROverviewofIntegratingNFRwithFRExtensionsofNFRFrameworkExampleofintroducingNFRtoFRExampleofintroducingNFRtoFRExampleofintroducingNFRtoFRExampleofintroducingNFRtoFRExtensionsofNFRFrameworkClassDiagramIntegrationProcessClassDiagramIntegrationProcessClassDiagramIntegrationProcessClassDiagramIntegrationProcessResulttoInspectSampleNumberTestResultInputResult()AssigntoAdmittedTest()ReadFromAnalyzer()CheckAuthorization(){Security[InspectTest]}CheckResultinRange(){Security[InspectTest]}CheckAuthorization()EmployeeisauthorizedtoInspectResultsCheckResultinRange()Result=Test.NR_Inpect.MinAndResult=NR_Inspect.MaxCheckSameSector()Test.Sector=Employee.SectorInputResult()Pre:CheckAuthorization=TrueAskResult()Pre:CheckSameSector=TrueSetResult()Pre:CheckResultinRange=TrueORNR_OutofSecureRange{Accuracy[ResultstoInspect]}SetResult()AskResult()ResulttoInspectSampleNumberTestResultInputResult()AssigntoAdmittedTest()ReadFromAnalyzer()CheckAuthorization(){Security[InspectTest]}CheckResultinRange(){Security[In