软体品质管理课件

軟體品質管理軟體品質管理1IntroductionWhatissoftwarequality?Howcanitbemeasured?Howcanitbemeasuredbeforethesoftwareisdelivered?SomekeyqualityfactorsSomemeasurableindicatorsofsoftwarequalityIntroductionWhatissoftwareq2IntroductionThinkofaneverydayobjecte.g.achairHowwouldyoumeasureit’s“quality”?constructionquality?(e.g.strengthofthejoints,…)aestheticvalue?(e.g.elegance,…)fitforpurpose?(fortable,…)AllqualitymeasuresarerelativethereisnoabsolutescalewecansayAisbetterthanBbutitisusuallyhardtosayhowmuchbetterForsoftware:constructionquality(建造的品質)?softwareisnotmanufacturedaestheticvalue(美學上的價值)?butmostofthesoftwareisinvisibleaestheticvaluemattersfortheuserinterface,butisonlyamarginalconcernfitforpurpose?NeedtounderstandthepurposeIntroductionThinkofaneveryd3軟體品質因素軟體品質因素4MeasuringQualityTheQualityConcepts(abstractnotionsofqualityproperties)MeasurableQuantities(definesomemetrics)CountstakenfromDesignRepresentations(realizationofthemetrics)usabilityminutestakenforsomeusertask???timetakentolearnhowtouse?complexitycountprocedurecalls???informationflowbetweenmodules?reliabilityrunitandcountcrashesperhour???meantimetofailure?examples...MeasuringQualityTheQualityC5FourKeyQualityConceptsReliabilitydesignermustbeabletopredicthowthesystemwillbehave:completeness-doesitdoeverythingitissupposedtodo?(e.g.handleallpossibleinputs)consistency-doesitalwaysbehaveasexpected?(e.g.repeatability)robustness-doesitbehavewellunderabnormalconditions?(e.g.resourcefailure)EfficiencyUseofresourcessuchasprocessortime,memory,networkbandwidthThisislessimportantthanreliabilityinmostcasesMaintainabilityHoweasywillitbetomodifyinthefuture?perfective,adaptive,correctiveUsabilityHoweasyisittouse?FourKeyQualityConceptsRelia6McCall’sQualityFactorsoperationrevisiontransitionCorrectnessreliabilityusabilityintegrityefficiencyMaintainabilityFlexibilityTestabilityPortabilityReusabilityInteroperabilityMcCall’sQualityFactorsoperat7General

utilityportabilityAs-isutilityMaintainabilityreliabilityefficiencyusabilitytestabilityunderstandabilitymodifiabilitydevice-independenceself-containednessaccuracycompletenessrobustness/integrityconsistencyaccountabilitydeviceefficiencyaccessibilitycommunicativenessself-descriptivenessstructurednessconcisenesslegibilityaugmentabilitySource:SeeBlum,1992,p176General

utilityportabilityAs-8ProductoperationusabilityProductrevisionProducttransitionintegritymaintainabilitytestabilityreusabilityportabilityinteroperabilityoperabilitytrainingI/OvolumeAccesscontrolAccessauditStorageefficiencyconsistencyinstrumentationexpandabilitygeneralitySelf-descriptivenessmodularitymachineindependences/monalityefficiencycorrectnessreliabilityflexibilitycommunicatativenessI/OrateexecutionefficiencySource:SeevanVliet2000,pp111-3traceabilitycompletenessaccuracyerrortolerancesimplicityconcisenessdatacommonalityProductoperationusabilityProd9MeasurablePredictorsofQualitySimplicitythedesignmeetsitsobjectivesandhasnoextraembellishmentscanbemeasuredbylookingforitsconverse,complexity:controlflowcomplexity(numberofpathsthroughtheprogram)informationflowcomplexity(numberofdataitemsshared)namespacecomplexity(numberofdifferentidentifiersandoperators)Modularitydifferentconcernswithinthedesignhavebeenseparatedcanbemeasuredbylookingat:cohesion(howwellcomponentsofamodulegotogether)coupling(howmuchdifferentmoduleshavetocommunicate)MeasurablePredictorsofQuali10QualityandhowtoachieveitProductquality–alwaysanissueAfterWWII,industryintheUSandelsewherehassubstantiallyimprovedqualityviaextensivetestingandstatisticalqualitycontrolJapaneseindustryhasfollowedadifferentconcept,a.k.a.totalqualityinitiative(Deming,Juran),wherequalitycontrolisanintrinsicaspectoftheproductionprocess,notapost-productionactivityInotherwords,youshoulddesignthequalityproductandbuilditright,ratherthanbuilditandthenmakesureithasgoodqualityQualityandhowtoachieveitP11SEIandtheCapabilityMaturityModelSoftwarequalityimprovementhasledtotheestablishmentoftheSoftwareEngineeringInstituteatCarnegie-MellonUniversityCapabilityMaturityModel(CMM)aframeworktoassessthematuritylevelofanorganization’ssoftwaredevelopmentandmanagementprocessesCMMconsistsoffivelevelsofmaturityasmeasuredbyasetofguidelinescalledthekeyprocessareasHigherlevelsincreasecompetitiveness,reduceriskLevelsaremonotonic:levelnincludesallthecharacteristicsofallthelevelsbelow,n-1,n-2,etc.SEIandtheCapabilityMaturit12CapabilityMaturityModelLevel5OPTIMIZEDLevel4MANAGEDLevel3DEFINEDLevel2REPEATABLERISKCOMPETITIVENESSLevel1INITIALCapabilityMaturityModelLevel13Level1—Initialend…SoftwaredevelopmentfollowsnoprescribedprocessYoudon’tknowwhereyoustand,orwhenwillyoufinish,orwhatyouwillgetwhenyoufinishYouhavetobehappywithwhatyougetattheLevel1—Initialend…Software14Level2—RepeatableProjectmanagementprocessesandpracticesareestablished,inordertotrackprojectcosts,schedules,andfunctionalityStill,youjustpassivelytrackwhat’sgoingon…anddon’tknowexactlywhatyoushoulddoLevel2—RepeatableProjectmana15Level3—DefinedAstandardsystemdevelopmentprocess(sometimescalleda“methodology”)purchasedordeveloped,andintegratedthroughouttheITunitoftheorganization…whichmeansthatthereisaprescribedsequenceofstepstofollow,plusyoumonitortheoutcomesLevel3—DefinedAstandardsyst16Level4—ManagedMeasurablegoalsforqualityandproductivityareestablishedConstantmonitoringgivesreal-timedataaboutthestatusoftheprocessandproductProcessparametersadjustedinordertoobtaindesiredoutcomes(thatismanagement,afterall)Level4—ManagedMeasurablegoal17Level5—OptimizingThestandardizedsystemdevelopmentprocesscontinuouslymonitoredandimproved,basedonmeasuresanddataanalysisestablishedinLevel4Changescanbemadetoprocessparameters…Butwecanmakechangeintheprocessitself(e.g.,choosedifferentsequence,changepriorities,evenintroduceadditionalstepsordeletesomethatdonotcontributetotheprocess/productquality)Level5—OptimizingThestandard18CMMcertificationprocessCMMassessmentperformedbyqualifiedpersonnelfromSEI,throughinterviewsandanalysisofproceduresanddocumentsusedintheorganizationLevelscanbeawardedtoorganizationsorspecificprojects/projectgroupswithinanorganization.Eachlevelhasitsownquestionnaire,withanumberofmandatoryandoptionalquestionsInordertoqualifyforaspecificlevel,Yesanswersmustbepresentineachgroup(thoughminimumpercentagesaredifferent)CMMcertificationprocessCMMa19CMMcertificationprocessEachquestionnairefocusesonanumberoftheso-calledKeyProcessAreas(KPAs)EachlevelofCMMscalehasanassociatedsetofKeyProcessAreas(KPAs)Toqualifyforaspecificlevel,issuesrelatedtoKPAsforthatlevelmustbeaddressedToprogressfromoneleveltothenextoneup,improvementsinappropriateKPAshavetobemadeLevelsaremonotonic–makesnosensetoconcentrateonKPAsfor,say,level4,ifthedevelopmentprocessisstillatlevel1or2CMMcertificationprocessEach20關鍵流程領域（KeyProcessArea,KPA)階層特徵關鍵流程領域（KPA）品質方法5最佳層（Optimizing）持續流程改善最佳化的管理◎缺陷預防

◎技術變更管理

◎流程變更管理從流程變異最小化4管理層（Managed）產品與流程品質評量定量化的管理◎定量流程管理

◎軟體品質管理從預防問題發生3定義層（Defined）流程定義與制度化定性化的管理◎組織流程特徵

◎組織流程定義

◎同等審查

◎訓練課程

◎整合軟體管理

◎軟體產工程

◎群體間協調及早發現問題與矯正2重覆層（Repeatable）專案管理使用經驗的管理軟體專案追蹤◎軟體專案計畫

◎軟體副合約管理

◎軟體品質保證

◎軟體構型管理

◎需求管理專案最終的測試1初始層

（Initial）個人主義，毫無章法的管理關鍵流程領域（KeyProcessArea,KPA)階21SomeproblemswithCMM(atleastinitially)Focusesonproject/processmanagement,notproductdevelopmentIgnoresuseofcertainadvancedtechnologiesDidnotincorporateriskanalysisasaKPADidnotdefineitsdomainofapplicabilitySomeproblemswithCMM(atleas22Butthingshaveevolved/diversified:ModelsthattheSEIiscurrentlyinvolvedindeveloping,expanding,ormaintaining:CapabilityMaturityModelIntegration(CMMISM)SW-CMMCapabilityMaturityModelforSoftwareP-CMMPeopleCapabilityMaturityModelSA-CMMSoftwareAcquisitionCapabilityMaturityModelSE-CMMSystemsEngineeringCapabilityMaturityModelIPD-CMMIntegratedProductDevelopmentCapabilityMaturityModelButthingshaveevolved/divers23ISO9000ISO9000seriesofqualitystandards,someofwhicharerelatedtosoftwareandISdevelopmentISOprinciples:SaywhatyouwilldoDoasyouhavesaidProvethatyoudidsoNOTE:thisisaverysimplifiedview–thecertificationprocessandthedocumentationrequiredtogothroughitarequiteextensiveanddetailedISOcertificationisperformedthroughnationalstandardsorganizationsISO9000ISO9000seriesofquali24CMMvs.ISOPartialoverlap,butdoubtsremainItseemspossiblethatanorganizationcanbecertifiedforISO9000andstillbeatlevel1oftheCMMscale,orbeatlevel3or4andstillunabletoobtainISO9000certificationNote:neitherISOnorCMMprescribeanyABSOLUTElevelofquality…buttheimprovementsinprocessmanagementarebelievedtohaveabeneficialeffectonqualityCMMvs.ISOPartialoverlap,bu25SQA:WhatisSQA?SQAistheprocessofassuringpeoplethateveryefforthasbeenmadetoensurethatsoftwareproductshavethedesiredlevelofreliability,maintainability,usability,andsalability.SQA是一種執行軟體評估與衡量的活動(BakerandFisher)Setofsystematicactivitiesprovidingevidenceoftheabilityofthesoftwareprocesstoproduceasoftwareproductthatisfittouse(G.SchulmeyerandJ.McManus,SoftwareQualityHandbook,PrenticeHall,1998.)SQA:WhatisSQA?SQAisthepr26SoftwareQualityAssuranceHowdoyouassurethequalityofyoursoftware?GoodprocessesGooddocumentationandartifactsAccountabilityLearnandimproveSoftwareQualityAssuranceHow27TheObjectivesofSQAMonitoringprocessesandproductsthroughoutthesoftwaredevelopmentlifecycletoensurethequalityofthedeliveredproduct(s)MonitoringtheprocessesProvidesmanagementwithobjective(客觀的)feedbackregardingprocesscompliance(承諾)toapprovedplans,procedures,standards,andanalysesMonitoringtheproductsFocusonthequalityofproductwithineachphaseoftheSDLCe.g.,requirements,testplan,architecture,etc.Objective:identifyandremovedefectsthroughoutthelifecycle,asearlyaspossibleTheObjectivesofSQAMonitorin28SQA:AnSQAProgramMinimizingnumberofdefectsindelivereds/wCreatingmechanismsforcontrollingsoftwaredevelopmentandmaintenancesothatcostsandschedulescanbemetMakingcertainthatthedeliveredproductcanbeusedinitsintendedmarketplaceImprovingthequalityoffutureproductsSQA:AnSQAProgramMinimizing29SoftwaredefectsMistakesmadeatanypointinthesoftwareprocessRequirements,design,coding,maintenanceConsequencesInconvenience,lossofservice,financialloss,equipmentdamage,injury,deathSoftwaredefectsMistakesmade30ThepercentageofdefectsfoundbyvariousmethodsPersonalcheckingofdesigndocumentsInformalgroupdesignreviewsFormaldesignspecificationsFormalcodeinspectionsModelingorprototypingPersonaldesk-checkingofcodeUnittesting(singleroutines)Functiontesting(relatedroutines)IntegrationtestingFieldtesting35%40%55%60%65%40%25%35%45%50%Thepercentageofdefectsfoun31Thetruthofdefects1.Thelaterinthelifecyclethatanerrorisdetectedthemoreexpensiveitistorepair.2.Errorsremainlatentandarenotdetecteduntilwellafterthestageatwhichtheyaremade.54%oferrorsdetectedaftercodingandunittesting.45%oftheseerrorswererequirementsanddesignerrors.3.Therearenumerousrequirementserrors.Estimatesindicatethat56%ofallerrorsareerrorsduringtherequirementsstage. 4.Requirementserrorsaretypicallynon-clerical.Thetruthofdefects1.Thelat32RelativeCosttoRepairbasedonwhenitwasfoundRequirements-1timeDesign-3-6timesCode-10timesUnittest-15-40timesSystemtest-30-70timesFieldoperation-40-1000timesRelativeCosttoRepairbased33Whenshouldqualityassurancebedone?AteverystageinthesoftwareprocessWhenshouldqualityassurance34TheProcessofSQA定義品質需求制定SQA計畫需求評估設計評估測試評估需求分析設計測試評估客戶滿意需求程度measurementfeedbackfeedback功能與完整性系統完整性與一致性執行效率與正確性TheProcessofSQA定義品質需求制定SQA計35SQAPlanningIEEEStd730-2002StandardforSoftwareQualityAssurancePlans12pagesIEEEGuideforSoftwareQualityAssurancePlanningdraftP730.287pagesSQAPlanningIEEEStd730-200236SQAPlanningIEEESQAPPurpose(Section1oftheSQAP)Referencedocuments(Section2oftheSQAP)Management(Section3oftheSQAP)Documentation(Section4oftheSQAP)Standards,practices,conventions,andmetrics(Section5oftheSQAP)Reviewsandaudits(Section6oftheSQAP)Test(Section7oftheSQAP)Problemreportingandcorrectiveaction(Section8oftheSQAP)Tools,techniques,andmethodologies(Section9oftheSQAP)Codecontrol(Section10oftheSQAP)Mediacontrol(Section11oftheSQAP)Suppliercontrol(Section12oftheSQAP)Recordscollection,maintenance,andretention(Section13oftheSQAP)Training(Section14oftheSQAP)Riskmanagement(Section15oftheSQAP)SQAPlanningIEEESQAP37ContentsofSQAPlan(sect1&2)PurposelistsoftwarecoveredstateportionofsoftwarelifecyclecoveredReferenceDocumentscompletelistofdocumentsreferencedelsewhereContentsofSQAPlan(sect1&238Sect3-Managementorganization-depictstructureoforg.responsibilitiestaskstaskstobeperformedrelationshipbetweentasksandcheckpointssequenceoftasksresponsibilitiesofeachorganizationalunitSect3-Managementorganizatio39Sect4-Documentationidentify

requireddocumentsstatehowdocumentswillbeevaluatedminimumdocumentsSRS-SoftwareRequirementsSpecificationSDD-SoftwareDesignDescriptionSVVP–S.VerificationandValidationPlanSVVR-S.VerificationandValidationReportUserdocumentation-manual,guideSCMP–S.ConfigurationManagementPlanSect4-Documentationidentify40Sect5-Standards,Practices,ConventionsandMetricsIdentifyS,P,C,andMtobeappliedHowcomplianceistobemonitoredandassuredMinimumdocumentationstandards,logicstructurestandards,codingstandards,testingstandardsselectedsqaproductandprocessmetricse,g,branch,decisionpointsSect5-Standards,Practices,41Sect6-ReviewsandAuditspurposedefinewhatreviews/auditswillbedonehowtheywillbeaccomplishedwhatfurtheractionsarerequiredMinimumSoftwareRequirementsReviewsPreliminaryDesignReviewevaluatetechnicaladequacyoftop-leveldesignSect6-ReviewsandAuditspur42MinSetofReviews/Audits(cont)CriticalDesignReviewacceptabilityofdetaileddesignsSoftwareVerificationandValidationPlanReviewadequacyofplannedverificationandvalidationFunctionalAuditallrequirementsinSRShavebeenmetPhysicalAuditsoftwareanddocumentsareconsistentandreadyIn-ProcessAuditManagerialReviewsMinSetofReviews/Audits(con43Sect7-TestAllteststhatarenotincludedinSVVPSect7-TestAllteststhatar44Sect8-ProblemReportingPracticesandProceduresforreporting,tracking,andresolvingproblemsOrganizationalresponsibilitiesSect8-ProblemReportingPrac45Sect9-Tools,TechniquesandMethodologiesidentifythespecialsoftwaretools,techniquesandmethodologiespurposedescribeuseSect9-Tools,Techniquesand46ProcessAssessmentUseofstandardsandprocessmodelshasapositiveimpactonthequalityofthesoftwareproductDisciplined,controlleddevelopmentprocessExamplesinclude:ISO9001CMMCMUSEI,5levelsSPICE(ISO/IEC15504)SoftwareProcessImprovement&CapabilitydEterminationDevelopingastandardforsoftwareprocessassessmentISOjointcommittee,Europe,AustraliaIEEE1074,IEEE12207ProcessAssessmentUseofstand47ProductAssessmentReviews,inspections,walkthroughsofPlans,reports,models,standardsProjectmanagement,qualityassurance,training,testplan(s)Requirements,analysis,architecture,detaileddesignmodel,testcasesIssueorproblemreportsMetricreportsTraceabilityreportsDocumentation,codingstandards…ProductAssessmentReviews,ins48SoftwareReviewsTheymayincludemanagerialreviews,acquirer-supplierreviews,technicalreviews,inspections,walkthroughs,andaudits.Inspection:Aformalevaluationtechniqueinwhichanartifact(e.g.,softwarerequirements,design,orcode)isexaminedindetailbyapersonorgroupotherthantheoriginatordetectfaults,violationsofdevelopmentstandards,andotherproblems.reviewmembersarepeers(equals)ofthedesignerorprogrammer.dataiscollectedduringinspectionsforlateranalysisandtoassistinfutureinspections.SoftwareReviewsTheymayinclu49ProblemReporting,Tracking,andResolvingDescribethepracticesandprocedurestobefollowedforreporting,tracking,andresolvingproblemsWhocanreportaproblem?Howisitreported?Howisittracked?Whodeterminesifitisaproblemthatgoingtoberesolved?Howisitassignedforresolution?Howdoesthepersonindicateithasbeencorrected?Whoreviewsittodetermineifitcanbeclosed?Problemscanbeproductorprocessrelatede.g.incorrectrequirement,incompleteclassdefinition,codedefect,ambiguousdescriptioninuserdocumentation,processtoreviewdetaileddesignisnotclearlydefined,etc.ProblemReporting,Tracking,a50SQA:6SIGMAQUALITYSigma=“StandardDeviation”Typicalsoftwarehas3to4defectsperKLOC6Sigma=3to4defectspermillionlinesofcodeAveragecompaniesaccept99.98%quality=4S6Sigma=99.9999998%levelofqualitySQA:6SIGMAQUALITYSigma=“S51SQA:6SIGMAQUALITYQualityImprovements:3Sigmato4Sigma=10fold4Sigmato5Ssigma=30fold5Sigmato6Sigma=70foldBest-in-Classcompaniesinsomeindustriesoperateat6Sigma(Airline=6.4Sigma;2.5M:1)SoftwareorganizationsneedtoassessthisSQA:6SIGMAQUALITYQualityIm52SQA:QualitySoftwarePeopleProcessManagementDisciplineSQASQA:QualitySoftwarePeoplePro53SQA:PursuingSQAWhatorganizationsaredoingNothing(42%)Slogans(口號)-“QualityisJobOne!”(4%)Improvedtesting(24%)Focusondefectprevention(20%)ProcessImprovements(9%)Other...(1%)SQA:PursuingSQAWhatorganiza54SQA:SoftwareReliability(MTBF)Putnam’sSoftwareReliabilityModelERRORS0NUMBEROFTIMEOperationalCapability0SQA:SoftwareReliability(MTB55SQA:PursuingSQAtheDemingWayPurposeincludesimprovementQualityphilosophyEliminatemassinspectionsAwardbusinessbasedonmorethanpriceContinuousimprovementInstituteOJT(Onthejobtraining)InstituteLeadershipDriveoutfearBreakdownbarriersEliminateslogansEliminatenumericalquotas&goalsRemovebarrierstoprideofworkmanshipInstituteeducationandself-improvementGeteveryoneinvolvedSQA:PursuingSQAtheDemingW56SQA:StrategybyYourdonIfmanagementorcustomersays...Speeduptesting...justsayNO!Don’tworryaboutafewbugs...justsayNO!We’llpindownthespecslater...justsayNO!Don’tworry,itsjustabetaversion...justsayNO!Idon’tcareiftherearebugs,getitoutthedoor...justsayNO!SQA:StrategybyYourdonIfman57SummarySoftwarequalitygenerallymeansfitnessforpurposeneedtoknowwhatthatpurposeis……whatfunctionsmustitperform…whatotherpropertiesmustithave(e.g.modifiability,reliability,usability…)NotallqualityattributescanbemeasuredduringdesignbecausequalityisnotanattributeofsoftwareinisolationbutwecanlookforpredictorsReliability,efficiency,maintainability,usabilityareusuallythefourmostimportantqualityfactors…althoughdifferentauthorsgivedifferentlistsModularityisoftenagoodpredictorofqualitymeasureitbylookingatcohesionandcouplingSummarySoftwarequalitygenera58軟體品質管理軟體品質管理59IntroductionWhatissoftwarequality?Howcanitbemeasured?Howcanitbemeasuredbeforethesoftwareisdelivered?SomekeyqualityfactorsSomemeasurableindicatorsofsoftwarequalityIntroductionWhatissoftwareq60IntroductionThinkofaneverydayobjecte.g.achairHowwouldyoumeasureit’s“quality”?constructionquality?(e.g.strengthofthejoints,…)aestheticvalue?(e.g.elegance,…)fitforpurpose?(fortable,…)AllqualitymeasuresarerelativethereisnoabsolutescalewecansayAisbetterthanBbutitisusuallyhardtosayhowmuchbetterForsoftware:constructionquality(建造的品質)?softwareisnotmanufacturedaestheticvalue(美學上的價值)?butmostofthesoftwareisinvisibleaestheticvaluemattersfortheuserinterface,butisonlyamarginalconcernfitforpurpose?NeedtounderstandthepurposeIntroductionThinkofaneveryd61軟體品質因素軟體品質因素62MeasuringQualityTheQualityConcepts(abstractnotionsofqualityproperties)MeasurableQuantities(definesomemetrics)CountstakenfromDesignRepresentations(realizationofthemetrics)usabilityminutestakenforsomeusertask???timetakentolearnhowtouse?complexitycountprocedurecalls???informationflowbetweenmodules?reliabilityrunitandcountcrashesperhour???meantimetofailure?examples...MeasuringQualityTheQualityC63FourKeyQualityConceptsReliabilitydesignermustbeabletopredicthowthesystemwillbehave:completeness-doesitdoeverythingitissupposedtodo?(e.g.handleallpossibleinputs)consistency-doesitalwaysbehaveasexpected?(e.g.repeatability)robustness-doesitbehavewellunderabnormalconditions?(e.g.resourcefailure)EfficiencyUseofresourcessuchasprocessortime,memory,networkbandwidthThisislessimportantthanreliabilityinmostcasesMaintainabilityHoweasywillitbetomodifyinthefuture?perfective,adaptive,correctiveUsabilityHoweasyisittouse?FourKeyQualityConceptsRelia64McCall’sQualityFactorsoperationrevisiontransitionCorrectnessreliabilityusabilityintegrityefficiencyMaintainabilityFlexibilityTestabilityPortabilityReusabilityInteroperabilityMcCall’sQualityFactorsoperat65General

utilityportabilityAs-isutilityMaintainabilityreliabilityefficiencyusabilitytestabilityunderstandabilitymodifiabilitydevice-independenceself-containednessaccuracycompletenessrobustness/integrityconsistencyaccountabilitydeviceefficiencyaccessibilitycommunicativenessself-descriptivenessstructurednessconcisenesslegibilityaugmentabilitySource:SeeBlum,1992,p176General

utilityportabilityAs-66ProductoperationusabilityProductrevisionProducttransitionintegritymaintainabilitytestabilityreusabilityportabilityinteroperabilityoperabilitytrainingI/OvolumeAccesscontrolAccessauditStorageefficiencyconsistencyinstrumentationexpandabilitygeneralitySelf-descriptivenessmodularitymachineindependences/monalityefficiencycorrectnessreliabilityflexibilitycommunicatativenessI/OrateexecutionefficiencySource:SeevanVliet2000,pp111-3traceabilitycompletenessaccuracyerrortolerancesimplicityconcisenessdatacommonalityProductoperationusabilityProd67MeasurablePredictorsofQualitySimplicitythedesignmeetsitsobjectivesandhasnoextraembellishmentscanbemeasuredbylookingforitsconverse,complexity:controlflowcomplexity(numberofpathsthroughtheprogram)informationflowcomplexity(numberofdataitemsshared)namespacecomplexity(numberofdifferentidentifiersandoperators)Modularitydifferentconcernswithinthedesignhavebeenseparatedcanbemeasuredbylookingat:cohesion(howwellcomponentsofamodulegotogether)coupling(howmuchdifferentmoduleshavetocommunicate)MeasurablePredictorsofQuali68QualityandhowtoachieveitProductquality–alwaysanissueAfterWWII,industryintheUSandelsewherehassubstantiallyimprovedqualityviaextensivetestingandstatisticalqualitycontrolJapaneseindustryhasfollowedadifferentconcept,a.k.a.totalqualityinitiative(Deming,Juran),wherequalitycontrolisanintrinsicaspectoftheproductionprocess,notapost-productionactivityInotherwords,youshoulddesignthequalityproductandbuilditright,ratherthanbuilditandthenmakesureithasgoodqualityQualityandhowtoachieveitP69SEIandtheCapabilityMaturityModelSoftwarequalityimprovementhasledtotheestablishmentoftheSoftwareEngineeringInstituteatCarnegie-MellonUniversityCapabilityMaturityModel(CMM)aframeworktoassessthematuritylevelofanorganization’ssoftwaredevelopmentandmanagementprocessesCMMconsistsoffivelevelsofmaturityasmeasuredbyasetofguidelinescalledthekeyprocessareasHigherlevelsincreasecompetitiveness,reduceriskLevelsaremonotonic:levelnincludesallthecharacteristicsofallthelevelsbelow,n-1,n-2,etc.SEIandtheCapabilityMaturit70CapabilityMaturityModelLevel5OPTIMIZEDLevel4MANAGEDLevel3DEFINEDLevel2REPEATABLERISKCOMPETITIVENESSLevel1INITIALCapabilityMaturityModelLevel71Level1—Initialend…SoftwaredevelopmentfollowsnoprescribedprocessYoudon’tknowwhereyoustand,orwhenwillyoufinish,orwhatyouwillgetwhenyoufinishYouhavetobehappywithwhatyougetattheLevel1—Initialend…Software72Level2—RepeatableProjectmanagementprocessesandpracticesareestablished,inordertotrackprojectcosts,schedules,andfunctionalityStill,youjustpassivelytrackwhat’sgoingon…anddon’tknowexactlywhatyoushoulddoLevel2—RepeatableProjectmana73Level3—DefinedAstandardsystemdevelopmentprocess(sometimescalleda“methodology”)purchasedordeveloped,andintegratedthroughouttheITunitoftheorganization…whichmeansthatthereisaprescribedsequenceofstepstofollow,plusyoumonitortheoutcomesLevel3—DefinedAstandardsyst74Level4—ManagedMeasurablegoalsforqualityandproductivityareestablishedConstantmoni