Object-Role Modeling as a Domain Modeling Approach

Object-RoleModelingasaDomainModelingApproach

H.A.Proper1,A.I.Bleeker2,andS.J.B.A.Hoppenbrouwers1

1UniversityofNijmegen󰀁,Sub-facultyofInformatics,IRISGroup,Toernooiveld1,6525EDNijmegen,TheNetherlands,EUe.proper@acm.org,stijnh@cs.kun.nl2Luminis,IJsselburcht3,6825BSArnhem,TheNetherlands,EUaraminte.bleeker@luminis.nl

Publishedas:

H.A.Proper,A.I.Bleeker,andS.J.B.A.Hoppenbrouwers.Object-rolemodellingasado-

mainmodellingapproach.InJ.GrundspenkisandM.Kirikova,editors,Proceedingsof

theWorkshoponEvaluatingModelingMethodsforSystemsAnalysisandDesign(EMM-

SAD’04),heldinconjunctiunwiththe16thConferenceonAdvancedInformationSystems

2004(CAiSE2004),volume3,pages317–328,Riga,Latvia,EU,June2004.Facultyof

ComputerScienceandInformationTechnology.

Abstract.ThispaperfocusesonthepotentialroleoftheObject-RoleModeling(ORM)approachtoinformationmodelingforthetaskofdomainmodeling.Domainmodelingcon-cernsobtainingandmodelingthelanguage(concepts,terminologies,ontologies)usedbystakeholderstotalkaboutadomain.Achievingconceptualclarityandconsensusamongstakeholdersisanimportantyetoftenneglectedpartofsystemdevelopment,andrequire-mentsengineeringinparticular.Thispaperstartsoutwithabriefdiscussionontheimportanceofdomainmodelinginsystemdevelopment.Thisisfollowedbyanoutlineoftheactivitiesinvolvedinproperdomainmodeling.WewillthendiscusswhytheORMapproachis,inprinciple,agoodcandidateforthetasksinvolvedindomainmodeling.Thisisfurthersubstantiatedbyamoredetailedevaluation,bothfromatheoreticalandapracticalperspective.

1Introduction

Intoday’sbusiness,softwareprojectsstilloftenfail,and/ortheircoststendtoturnouttobehigher

thaninitiallyestimated[1].Variousdifferentreasonsmayunderliethisproblem,betheypolitical,

organizational,economic(budgets)orprocess-oriented.Webelievethatoneofthekeyfactors

contributingtowardsfailureisalackofclarityregardingthelanguageandconceptsusedinthe

communicationamongthestakeholdersinvolvedinthedevelopmentproject.Thesestakeholders

typicallyrangefromproblemowners,contractauthorities,perspectiveusers,domainexperts,to

softwareengineersandsystemadministrators.

Achievingconceptualclarityandconsensusamongstakeholdersisanimportantyetoften

neglectedpartofmodelingactivitiesinsystemdevelopment.Duringsystemdevelopment,amyriad

ofmodelsmaybeproduced,rangingfromhighlevelsketchesoftheproblem,viainformal/formal

requirements,todesignsatseverallevelsoftechnicaldetail.Underlyingeachofthesemodelsa

setofdomainspecificconceptscanbediscerned,suchasclient,order,stock,etc.Theprocessof

obtainingandmodelingtheseconcepts,essentiallymodelingthelanguage(concepts,terminologies;

ontologies)usedbystakeholderstotalkaboutadomain,iswhatwerefertoasdomainmodeling.

Theabsenceofexplicitandwellmanageddomainmodelsplaysanimportantpartinthe

failureofasignificantnumberofsystemdevelopmentprojects[2].Achievingclarityandconsensus

󰀁ThispaperresultsfromtheArchiMateproject(http://archimate.telin.nl),aresearchconsortiumthataimstoprovideconceptsandtechniquestosupportenterprisearchitectsinthevisualisation,communicationandanalysisofintegratedarchitectures.TheArchiMateconsortiumconsistsofABNAMRO,StichtingPensioenfondsABP,theDutchTaxandCustomsAdministration,Ordina,TelematicaInstituut,CentrumvoorWiskundeenInformatica,KatholiekeUniversiteitNijmegen,andtheLeidenInstituteofAdvancedComputerScience.amongstakeholdersaboutthedomainconceptsused,boilsdowntoansweringthequestion:what

arewetalkingabout?Thepurposeofadomainmodelisthereforetouniformlydefineandscopethe

domainconceptsintermswhichthestakeholdersunderstandandagreeupon.Forthestakeholders

inthebusinessenvironment,thedomainmodelcanprovideaunifiedvocabularyandsupport

understandingofthescopeofthesystem;towardssoftwarearchitectsandengineersitprovides

guidanceinmakingimplementationdecisions(forexampledatabasedesign).Fortheprojectleader

itcanbeanaidinplanningandprioritizationoftheproject.

Giventhatdomainmodelsarecentralinstakeholdercommunication,terminologicalaspects

ofmodelingcanbestbetackledindirectrelationtosuchmodels.Thisshouldensuretimely

identificationofterminology-relatedissues,yetkeepsoptionsopenastohowsuchissuesaretobe

solvedormanaged(thatis,inwhichway,andinwhichdevelopmentphase).Thedifferentmodels

usedduringsystemdevelopment,andtheirunderlyingdomainmodel(s),needtobecommunicated

withdifferentstakeholders.Thisputsanextraburdenonthetaskofdomainmodeling,asashared

understandingmustbereachedoftheconceptsinvolved.

Wearenotaloneinarguingtheimportanceofdomainmodeling.Forexample,theRational

UnifiedProcess[3](RUP)explicitlyunderlinesitsimportanceaswell.TheRUPincludesthenotion

ofaglossary,whichisusedtodefineterminologyspecifictothebusinessdomain,explainingterms

whichmaybeunfamiliartothereaderofuse-casedescriptionsorotherprojectdocuments.Quite

often,thisdocumentisusedasaninformaldatadictionary,capturingthedefinitionsoftheterms.

However,webelievethatRUP’snotionofaglossary,inparticularwhenviewedasa“listofterms”,

istoolightamechanismfordomainmodelling.

In[4]theimportanceofproperdomainmodelingisarguedaswell.Thebookspentsanentire

chapterontheissuesinvolvedindomainmodeling.It,however,doesnotprovideexplicitguidance

tomodelers,notdoesitprovideanunderlyingtheoryofdomainmodeling.Webelievethatsuch

anunderlyingtheoryshouldbedeveloped,andthatmoreguidanceshouldbeprovidedtodomain

modelersinpractice.Thisarticleaimstotakesomefirststepsintothisdirection,byevaluating

ORMfromtheperspectiveofdomainmodelling.

Theaimofthisarticleistoprovideabriefanalysis,bothfromatheoreticalandpracticalper-

spective,ofthecomplexitiesinvolvedindomainmodelingandthepotentialuseofORMforthe

tasksinvolved.Wewillidentifyseveralambitionlevelsconcerningthedomainmodelingprocess

(section2)[5].Basedonthistheoreticalanalysis,wewill(section3)thencontinuebydiscussing,

fromatheoreticalperspective,howtheORM(Object-RoleModeling)[6]approachcanbeem-

ployedforthetaskofdomainmodeling.WewillarguethatORM’srootsinnatural-language

analysismakesithighlysuitableforthistask.Somealternativemodelingapproaches,suchas

OOSA[7]andtheUML[8]willbediscussedbrieflyaswell.Beforeconcluding,section4focuses

onsomepracticalexperienceswiththeuseofORMinsoftwaredevelopmentprojects.

2DomainModeling

Thissectionprovidesabriefdiscussionoftheactivityofdomainmodeling.Amoredetailed

discussionondomainmodeling,anditsroleinthesystemdevelopmentprocess,canbefound

in[2,5].Ingeneral,thegoalsfordoing(business)domainmodelingare[2]:

1.articulateclearandconcisemeaningsofbusinessdomainconceptsand

2.achieveasharedunderstandingoftheconceptsamongrelevantstakeholders.

Ourstartingpointisnotthedomainmodel(aconceptualrepresentation),buttheactors(typically

people)thataresomehow–andrelevantly–involvedindiscoursingaboutadomain.Theyoperate

inanenvironmentofdiscourse3.

Basedontheresultsreportedin[10],weconsiderdomainmodelinginthecontextofsystem

developmenttorevolvearoundthreestreamsof(mutuallyinfluencing)activities:

3Foranin-depthdiscussionofthenotionof“environmentofdiscourse”inrelationwiththeclassicnotionof“universeofdiscourse”,see[9].