Transformation simulation

Applying UML and software simulation for process definition, verification, and validation

Available online at http://wendang.chazidian.com

InformationandSoftwareTechnology50(2008)

897–911

http://wendang.chazidian.com/locate/infsof

ApplyingUMLandsoftwaresimulationforprocess

de?nition,veri?cation,andvalidation

Nien-LinHsueh,Wen-HsiangShen*,Zhi-WeiYang,Don-LinYang

DepartmentofInformationEngineeringandComputerScience,FengChiaUniversity,100WenhwaRoad,Seatwen,Taichung40724,Taiwan,ROC

Received8April2007;receivedinrevisedform15October2007;accepted23October2007

Availableonline4November2007

Abstract

Processde?nition,veri?cation,andvalidationarerecognizedascriticalelementsinsoftwareprocessimprovement,whereasCMMIisaprocessimprovementapproachthatprovidesorganizationswiththeessentialelementsofe?http://wendang.chazidian.comanizationsmustde?netheirownprocessestomeettherequirementsofCMMI.Afriendly,unambiguousprocessmodelinglanguageandtoolarethusveryimportantfororganizationstode?ne,verify,andvalidatetheprocesses.Nevertheless,hardlyhasanyresearchyetbeendoneonhowtoembedCMMIprocessareagoalsintoprocessde?nitionstagetosatisfyorganizationprocessimprovement.Inthisresearch,wepro-poseaUML-basedapproachtode?ne,verify,andvalidateanorganization’sprocess.Ourapproachcanalsobeappliedtoaprocesslearningenvironmentforstudentsandprojectmembers.Ó2007ElsevierB.V.Allrightsreserved.

Keywords:CMMI;UML;Processmodeling;Processsimulation;Softwareengineeringeducation

1.Introduction

Inrecentyears,agreatdealofe?orthasbeendevotedtosoftwareprocesses,andtheindustryhasalsoputsuchimprovementintoaction,especiallyintheCMMI(Capa-bilityMaturityModelIntegration)perspective[3,22].CMMIcanbeusedtoguideprocessimprovementacrossaproject,adivisionoranentireorganization.Themodelhelpsintegratetraditionallyseparateorganizationalfunc-tions,setsprocessimprovementgoalsandpriorities,andprovidesguidanceforqualityprocessesandapointofref-erenceforappraisingcurrentprocesses.Simulationhasalongandsuccessfulhistoryinindustries[10,23,24]andcanenhancetraditionalprocessde?nitioninthedrivetoimprovethesoftwareprocess[16].Processde?nitionisa?rmedasanimportantelementinsoftwareprocess

Correspondingauthor.Tel.:+886427016855x7697;fax:+886427073586.

E-mailaddresses:nlhsueh@fcu.edu.tw(N.-L.Hsueh),shen@ocit.edu.tw(W.-H.Shen),sundy.yang@http://wendang.chazidian.com(Z.-W.Yang),dlyang@fcu.edu.tw(D.-L.Yang).

0950-5849/$-seefrontmatterÓ2007ElsevierB.V.Allrightsreserved.doi:10.1016/j.infsof.2007.10.015

*

improvement.OnMarch2003,theO?ceofInformationTechnology(OIT)atFengChiaUniversitystartedontheCMMI-basedprocessimprovement.Itsaimwastoachievematuritylevel3whichcontained18processareas,42goals,and130practices.Thisimpliesithadtode?nealmost130processesforthematuritylevel[8].WhenOITEPG(Engi-neeringProcessGroup,organizedtode?netheorganiza-tionprocesses)begantode?netheprocessesforprojectplan,monitoringandcontrol,con?gurationmanagement,etc.,itdeeplysensedtheimportanceofprocessde?nition,veri?cation,andvalidation–howtode?neaclearandcon-ciseprocessthatisreadableforallprocessperformers?Howcanonetelliftheprocessesaresu?cientforCMMIrequirements?Aretheprocessesconsistentwithoneanother?Aretheprocessesexecutableintheorganization?Processmodelinglanguageplaysanimportantroleinansweringtheafore-mentionedquestions[21].Manyrelatedresearchesconductrigorousprocessmodelinglan-guagestoavoidanycon?ict,suchasPetrinet[12,25]orwork?owmodelinglanguage[13].However,theseapproachesaretoocomplexforageneralprocessenact-mentroleofasoftwaredevelopmentunit.Bearinginmind

Applying UML and software simulation for process definition, verification, and validation

898N.-L.Hsuehetal./InformationandSoftwareTechnology50(2008)897–911

thatUni?edModelingLanguage(UML)[6,20]hasbecomethedesignstandardinthesoftwaredevelopmentarea,Thebene?tsofUML-basedprocessmodelare:(1)itprovidesdi?erentviewstopresentaprocess;(2)ito?ersanexten-sionmechanismtoallownotionextension;and(3)itusesObjectConstraintLanguage(OCL)tohelpmodelveri?ca-tion.Processvalidationisalsoanimportantissuewhileconductingprocessimprovement[5]–howcanonetelliftheprocessesproposedbyEPGaresuitableforstockhold-ers?Toaddressthisproblem,IDEAL[15]suggestsper-forminga‘‘pilot’’projecttoexaminethefeasibilityoftheproposedprocessesbeforetheorganizationbeginstoimplementthem.However,ifthede?nedprocessisimpro-per,executingthepilotprojectstillspenttheorganizationlargee?ortseventhepilotprojectisasmallone.Wepro-posetovalidateprocessesinasimulationenvironmentpriortothepilotprojectexecution,whichmayexplorepos-sibleproblemsinthede?nedprocessearlierandreducethee?ortsonthepilotprojectexecution.

http://wendang.chazidian.comingourapproach,anorganizationdevelopsitsprocessesinthefol-lowingsteps:processmodelde?nition,processmodelveri-?cation,modeltransformation,modelvalidation,processeducation,http://wendang.chazidian.comparingtootherformalprocessmodelinglanguageslikePetrinet,UMLiseasiertolearnduetoitsfamiliarity.Themodelersdonotneedtolearnnewnotationandsemanticswhende?ningprocesses.Inaddition,UMLprovidesObjectConstraintLanguageformodelingpreciseandveri?ablesemantics.Ourapproach,basedonUML,mayprovideaneasierandveri?ablewayforde?ningandverifyingsoftwarepro-cesses.EmbeddingasetofCMMI-relatedrulesinourpro-?lecanhelpverifyifthedevelopedprocessde?nitionmeetthebasicrequirementsofCMMIframework(Fig.1(b)).Forexample,oneoftherulesis‘‘allgoalsinaprocessareamustbesatis?ed’’,ourapproachcanhelpverifythisrulewiththeaidofobjectconstraintlanguage.Therefore,onde?ningorafterde?nition,wecandoprocessveri?cationtoverifywhetherthemodeledprocessesareconsistentwiththerulesde?nedintheprocesspro?le.WealsodesignasystemtotransformtheprocessmodelintoaSimSEpro-cesssimulationmodel(Fig.1(c)).SimSEprovidesan

Fig.1.Approachoverview.

opportunityforstakeholderstovalidatetheappropriate-nessforthedevelopedprocessbeforeapplyingtheprocess.Iftheprocessisnotsuitableforoperation,itissubjecttorevision(Fig.1(d)).Thesimulationcanalsoplaytheroleofeducationaftertheprocessisaccepted(Fig.1(e)).There-fore,wecanconductalight-weightprocessvalidationbeforethepilotprojectrun.Thisprocessenactiveenviron-mentprovidesaconvenientande?ectivemechanismforprocessde?nition,veri?cation,andvalidation.

Intheremainderofthispaper,themainfeaturesofrelatedapproachesandtechniquesaresummarizedinSec-tion2.Section3describesourproposedProcessModelPro?le(PMP)andhowtoapplyPMPtomodelaprocess’sstaticstructure,aprocesselement’sbehaviorandapro-cess’sdynamicprocesssequence.Section4describestheprocessveri?cationapproachonthebasisofobjectcon-straintlanguage.Section5describesthetransformationfromaPMPmodeltoaSimSEmodelandintroducestheapproachtovalidateaprocessbySimSEsimulation.Finally,Section6presentsashortconclusion.2.Backgroundwork

Therearesomeimportantresearchareasrelatedtoourwork,includingUML-basedprocessmodelingapproaches,UMLextensionmechanism,processveri?cationapproaches,andprocesssimulation.Thissectionessen-tiallyintroducestherelatedbackgroundworkforsuch.Intherecentpast,arelevante?orthasbeendevotedtothede?nitionofprocessmodelinglanguages(PMLs)[7,27].ManyresearchersandpractitionershaverecentlystartedexperimentingwiththeusageofUMLasaPML.Beingsopopularandwidelyused,UMLhasacompetitiveadvantagewhencomparedtoanyotherspecializedPML[9].Toincreasemodelunderstandabilityandtoreducemodelmaintenancee?ort,processmodelingshouldbesup-portedbyaveryhighlevelofabstraction.Besides,Soft-wareProcessEngineeringMetamodel(SPEM)[18]isdevelopedbasedonUMLtode?neasoftwareprocess.Itisusedtodescribeanorganizationprocessorafamilyofrelatedsoftwaredevelopmentprocesses.Itisalsoanobject-orientedapproachandusestheUMLasanotationtodomodeling.However,sinceSPEMisalargespeci?ca-tion,itisnoteasytoapply.Inaddition,sinceSPEMisusedforgeneralpurpose,itcannoto?eranysupportinde?ningCMMIprocesses.Withthisinmind,ourresearchfocusesmostlyonthisareainordertoresolverelatedproblems.AUMLpro?leisakindofvariantofUMLthatusestheextensionmechanismsofUMLinastandardizedway.Apro?lestereotypeofpackagecontainsoneormorerelatedextensionsofstandardUMLsemantics.ThesearenormallyintendedtocustomizeUMLforaparticulardomainorpurpose.Pro?lescancontainstereotypes,tagde?nitions,andconstraints.Theycanalsocontaindatatypesthatareusedbytagde?nitionsforinformallydeclar-ingthetypesofthevaluesthatcanbeassociatedwithtagde?nitions.Inaddition,apro?lepackagecanspecify

a

Applying UML and software simulation for process definition, verification, and validation

N.-L.Hsuehetal./InformationandSoftwareTechnology50(2008)897–911899

relatedmodelrepositoryandidentifyasubsetoftheUMLmetamodelthatisapplicableforthepro?le.Inprinciple,pro?lesmerelyre?nethestandardsemanticsofUMLbyaddingfurtherconstraintsandinterpretationsthatcapturedomain-speci?csemanticsandmodelingpatterns.Ourapproachistode?nebothasametamodelandasaUMLpro?le,whichallowsprocessmodelerstouseUMLasaconcretenotation.

MostworksdealingwithUMLveri?cationusingformalmethodtechniquesfocusonstatediagramveri?cation.Manysuchpapersarebasedonpreviousworksthat,usingformalmethods,veri?edthevariedUMLdiagrams[2,14,26].SofarastheuseofUMLissowidespread,researchersarelookingtotakeastepfurtherinUMLveri?-cationwithformalmethods.Researchisfocusingonobtain-ingtoolsthatautomaticallygivethesystemspeci?cationinaformallanguagewithouttheuser’sinvolvementand,asfarasispossible,toachieveanautomaticveri?cationprocess[1].Themaincharacteristicsofthispaperfocusonthepos-sibilityofperforminganautomaticveri?cationofthebehav-iorofaUMLspeci?cationinwhichthesaidbehaviorisre?ectedthroughstateandactivitydiagramsandisalsoincludeCMMI-veri?edconstraintsintoourapproach.

Simulationisawidelyusedandincreasinglypopularmethodforstudyingcomplexsystems[11],andthatChris-tieshowshowsimulationcanbeofsigni?cantbene?tinsupportingsoftwareprocessimprovement[4].Analystsusesimulationtostudyasystem,measureitsperformance,andimproveitsoperationordesignitifitdoesnotexist.Simulationalsofocusesattentiononunderstandinghowsystemscurrentlywork.Often,simulationanalysts?ndthattheprocessofde?ninghowthesystemworksprovidesgreatinsightintowhatchangesshouldoccur.SimSE[17]developedbytheUniversityofCaliforniaforprocessedu-cation,isaninteractive,graphical,educationalsoftwareengineeringsimulationgamedesignedtoteachstudentsdi?erenttypesofsoftwaredevelopmentlifecycle.Thissim-ulationenvironmentisasingle-playergameinwhichtheplayertakesontheroleofprojectmanagerofateamofdevelopers.

3.Processde?nition3.1.Processstructure

Fig.2describesthemetamodelofourstaticprocessstruc-turewithCMMIframework.Themodelingelementsbelowthedashlinepresentabasicorganization’sprocessstructure:processelementsandtheirrelationships.WorkProcessisakindofoperationthatdescribestheworkperformedintheprocess.ItsmainsubclassisWorkPractice.AWorkPracticemaybeasubWorkProcessandmayconsistasetofatomicelementscalledWorkSteps.Forexample,aWorkProcess–‘‘ProductDevelopment’’containsasubWorkProcess–‘‘SoftwareDesign’’.‘‘SoftwareDesign’’containsaWork-Step–‘‘Peerreview’’.EachWorkProcesscontainsatleastoneEntryCriteriaandoneExitCriteria.TheEntryCriteriaofa‘‘ProductDevelopment’’maybetheconditionthatuserrequirementshadbeendrafted.AProcessMemberde?nesamemberinanorganization.Ithastwosubclasses:Process-OwnerandProcessPerformer.AProcessPerformerde?nesaperformerforasetofWorkPracticesinaprocess.APro-cessOwnerde?nesanownerforasetofWorkProcesses.ThemodelingelementsabovethedashlineinFig.2aremod-elingelementsrelatedtoCMMIframework.Thematuritylevel(ML)ofCMMIprovidesawaytopredictthefutureperformanceofanorganizationwithinagivendisciplineorsetofdisciplines.Thematuritylevelhas?veranks.Inthisdiagram,onecandistinguishwhichmaturitylevelofanorganizationbycheckingthehierarchyofCMMIframe-work:ProcessAreas,Goals,andPractices.3.2.ProcessModelPro?le

WeapplypartofUMLSPEMpro?leutilizeUMLpro-?lingmechanism(asmentionedinSection2)toconstructaprocesspro?le,calledProcessModelPro?le(PMP).PMPde?nesanumberofusefulprede?nedmodelingelementsandhowtheyinteract.ThesestereotypesareappliedtoexistingUMLentities,suchasclassesandassociations,andtheyarguethesemanticsofthesestandard

elements

Fig.2.Staticprocessmetamodel.

Applying UML and software simulation for process definition, verification, and validation

900N.-L.Hsuehetal./InformationandSoftwareTechnology50(2008)897–911

withnewlyde?nedmeanings,allowingustomodelprevi-ouslyunsupportedconcepts.Table1givesasummaryofprocesspro?lestereotypes.

Wehadbuiltthepro?lebyRationalXDEstoredasanXML?le.Thepro?lecanbeappliedtoaprocessmodeltocustomizeourmodelingenvironment.Thefollowingpara-graphswilldescribehowwepresentaprocessbasedonthispro?le.

3.3.Thepracticesofprocessde?nition

UMLisusedtopresentdi?erentperspectivesofasys-temindi?erentdiagrams.AstheproposedPMPisanextensionofUML,wecanpresentdi?erentperspectivesofaprocessindi?erentdiagrams;theyareclassdiagramformodelingstaticprocessstructure,state-chartdiagramformodelingbehaviorofprocesselement,andactivitydia-gramformodelingdynamicprocesssequence.

3.3.1.ModelingstaticprocessstructurewithclassdiagramClassdiagramsshowthestaticstructureoftheprocessbeingmodeledfocusingontheelementsofaprocess,irre-Table1

Stereotypesoftheprocesspro?leStereotypeWorkArtifact

Baseclass

Core::Class

ActivityGraphs::ObjectFlow

State

Core::Constraint

spectiveoftime.Staticstructureisconveyedbyshowingthetypesandtheirinstancesintheprocess.Besidesshowingprocesstypesandtheirinstances,classdiagramsalsoshowatleastsomeoftherelationshipsamongandbetweentheseelementsandpotentiallyevenshowtheirinternalstructure.Fig.3(A)isanexampleoftheactivity‘‘Implementation’’,whichrepresentsitsrelationshipstootherprocesselements.ThemodeltellsusImplementationisoneofactivitiesoftheproductdevelopmentprocess;itneedsSystemDesignDoc-umentation(SDD),RequirementTraceabilityMatrix(RTM),andTestPlan(TP)asinputartifacts;itisper-formedbyanimplementer;anditwillgeneratesourcecodeandunittest.Fig.3(B)representshowaprocesscanrealizetheCMMIrequirements,i.e.,thediagrammodelstherela-tionshipbetweenaprocessandCMMIelements.Forexam-ple,theCMMIpractice‘‘ManageRequirementsChanges’’canberealizedbytheWorkPractice‘‘SoftwareDesign’’.Fig.3(C)modelsthegoal–practicerelationshipofthepro-cessarea‘‘RequirementManagement’’(abbreviatedasREQMonthetopofthe?gure).ThediagramshowsthatREQMhasonlyonespeci?cgoal‘‘ManageRequirement’’whichcanbeachievedbythefourspeci?cpractices.

StereotypeparentNotationExample

Customerrequirements

EntryCriteria

Do‘‘RequirementAnalysis’’beforerequirementsdrafted

Stop‘‘RequirementAnalysis’’afterrequirementdocument?nishedProductdevelopment

ExitCriteria

WorkProcess

Core::Constraint

Core::Operation

ActivityGraphs::ActionStateCore::Operation

ActivityGraphs::ActionState

Core::Operation

ActivityGraphs::ActionState

UseCases::ActorUseCases::Actor

UseCases::Actor

Core::ClassCore::ClassCore::ClassCore::Class

ProcessMemberProcessMemberWorkProcess

WorkPracticeRequirementanalysis

WorkStepWorkPracticeBaselinerequirements

ProcessMember

ProcessOwnerProcessPerformerCMMI_ML

CMMI_PA

CMMI_Goal

CMMI_Practice

Projectleader

ProcessDe?nitionTeamRequirementAnalyzerMaturitylevel2REQM,CM,PPQAManagerequirementsManagerequirementschanges

Applying UML and software simulation for process definition, verification, and validation

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Fig.3.Staticprocesswithclass

diagram.

Fig.4.Thestate-transitiondiagramofthe‘‘SystemAcceptanceForm’’

artifact.

3.3.2.Modelingbehaviorofprocesselementwithstate-chart

diagram

State-chartdiagramsareusedtoillustratethebehaviorof

aprocesselementsuchasWorkArtifact.Atransitionisa

kindofWorkProcess.Fig.4showsthestatetransitionof

theworkartifactSystemAcceptanceForm(SAF).ApprovedandAcceptedaretwode?nedstatesinPMP.WhentheworkprocessCustomerRequirementElicitationisperformed,SAFwillchangeitsstatefromApprovedtoAccepted.ThediagramisestablishedbythetoolRationalXDE,wherewehaveimportedourproposedprocesspro?le.Whenwemodelthestate-transitiondiagramofanartifactwiththetool,alltransitionsmustbeaworkprocessde?nedintheclassdiagram.Thebene?tsaretwofold:themodelercande?nethebehaviorjustbyselectingthede?nedworkprocesses;anditcanavoidde?ninganerroneousworkpro-cessinthebehaviormodel.3.3.3.ModelingdynamicprocesssequencewithactivitydiagramActivitydiagramshowsthe?owsfromactivitytoactivityandtheinput/outputWorkArtifactsfortheactivities.AWorkArtifacttogetherwithanassociatedstate,calledobject?owstate,isusedtorepresenttheentryandexitcriteriaforanactivity.Forexample,‘‘SystemProposal[Drafted]’’inFig.5representstheentrycriteria‘‘theworkartifactSystemProposalisinthedraftstate’’fortheactivityCustomerRequirementElicitation.Wealsoutilizetheconceptofswimlanesasamechanismtoorganizeactivitiesintosepa-ratevisualcategoriesinordertoillustratedi?erentfunc-tionalcapabilitiesorresponsibilities.Theswimlanescanbeusedtodistinguishtheresponsibilitiesofdi?erentProces-sPerformers.InFig.5therearetwoswimlanes.TheElicitorperformstheCustomerRequirementElicitationandtheAnalyzerperformstheSystemandSoftwareAnalysis.Notethattheclassmodeling,state-chartmodeling,andactivitymodelingareiterativeandinterrelated.TheEPGmaystartwithclassmodelingto?rstidentifyprocessele-mentsandtheirrelationships,followedbyusingstate-chartmodelingtodescribepossiblestatetransitionsofidenti?edprocesselements,andthenusingactivitymodelingtoiden-tifydynamicprocesssequences.Wemayrevisetheclassdiagramsinceweexploremoreclassesorattributesinthestate-chartmodelingoractivity

modeling.Fig.5.Activitydiagram.