Intherestofthispaper,weexaminethetrendforcreatingmeta-environments.First,we

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1 META-ENVIRONMENTSFORSOFTWAREPRODUCTION ComputerScienceDepartment,Loyola-MarymountUniversity InformationandOperationsManagementDepartment LosAngeles,CA USA ANTHONYS.KARRER LosAngeles,CA ,USA UniversityofSouthernCalifornia CenterforSoftwareEngineering December1994 WALTSCACCHI and wareproductionenvironmentswhichsupportparticularsoftwareengineeringmethodsmaynot fromwhichspecicsoftwareproductionenvironmentscanbecreated.inthispaper,weattempttocategorizemorethan60meta-environmenteorts.foreachofthecategories,we atrendtowardsresearchintowayswhichwilllessenthecostofdevelopingsoftwareproduction Researcherswhocreatesoftwareproductionenvironmentsfaceconsiderableproblems.Soft- reviewresearcheortswhichillustratedierentapproacheswithinthatcategory.weconclude environments.inparticular,thetrendhasbeentowardstheconstructionofmeta-environments beapplicabletoalargenumberofsoftwareproductionprojects.theseconditionshaveformed wareproductionenvironmentsarelargesystemsthatarecostlytodevelop.furthermore,soft- softwareengineeringmethods,suchasstructureddesignandobject-orientedanalysis,haveemerged toeasetheseproblems.recently,therehasbeenconsiderableattentionpaidtotheapplicationof 1Introduction Softwareengineeringaddressesthecomplexproblemsassociatedwithsoftwareproduction.Many bypresentinganemergingcommonthreadofrequirementswhichlinksthiseldtogether. thesemethodsthroughsoftwareproductionenvironmentsinordertoevaluatetheeectiveness ofeachmethod[7,43,67].asoftwareproductionenvironment(spe)isasystemconsistingof asoftwareinfrastructureprovidingacommonoperatingenvironmentforsoftwaretools,asetof tools,andaninterfacewhichprovidesuserswithaccesstotheenvironment'scapabilities. considerableproblemsinusingspetechnology.oneunderlyingproblemisthatsoftwareproductionenvironmentsarelargesystemsand,withoutsucientsupport,arecostlytoengineerand build.thisresultisnotsurprising,especiallygiventhatsoftwareproductionenvironmentsare largesoftwareproducts.coupledwiththisproblem,researchershavefoundthatlittleisknown abouttherequirementsforagoodspe.manyresearchersbelievethattheonlywayinwhichthe requirementscanbefoundisbydeveloping,using,andevolvingenvironments.unfortunately,such Bothsoftwareproductionorganizationsandresearchorganizationshavefoundthatthereare 1

2 anevolutionaryapproachwillbecostlybecauseofthetimeandeortrequiredforcreatingnew SPEs,andbecauseasbetterSPEsaredeveloped,usersarelikelytochangethemannerinwhich theyusethespe[67].worseyet,eachsoftwareproductionprojectmayhavedierentrequirements usedtoconstructspes.speconstructionprocesseshavetakenmanyforms,withearlyspesbeing foranspe[10].thesefactorsimplythatinordertoresearchtherequirementsforspesandto supporttherequirementsofindividualprojectswemustreducethecostofcreatingspes. powerfulconstructsthanaregenerallyavailableinprogramminglanguages.meta-environments havealsobeencalledgenericenvironments[36]andenvironmentgenerators[25,31,95].the Meta-environments[53,55,80]areemergingasameansofconstructingSPEswithsignicantlymore constructedusingasimpleprogram-debug-testprocessbasedonasingleprogramminglanguage. distinctionbetweenthesetermsissomewhatvague.assuch,wewillusethetermmeta-environment toincludegenericenvironments,environmentgenerators,andotherapproachestoenvironment BecauseSPEsarethemselvessoftwareproducts,wecanconsiderthesoftwareproductionprocess createanspe.anenvironmentspecicationisaninstantiatedconstructionmodelwhichspecies ofthemodelintoanspe,andaprocessforusingtheconstructionmodelandtransformationto roles,resources,tools,andtheirrelationshipswhichspeciestheproceduresusedtocreateviable theintendedenvironment.ameta-environmentconstructionprocessisthecollectionoftasks,agent construction. softwareproductionenvironments. isthatspesarethemselveslargesoftwaresystemsandareextremelycostlytocreatewithout Wendameta-environmentconsistsofaconstructionmodel,atransformationofinstances thesupportprovidedbymeta-environments.thesecondissueisthatahighlevelofassistance resultingenvironment.theseassumptionsreducetheabilityofameta-environmenttosupport inreducingthecostofenvironmentcreationoftenrequiresassumptionsabouttheformofthe manydierentkindsofsoftwareengineeringmethods. Ingeneral,meta-environmentsaredesignedtoovercometwomajorissues.Therstissue presentingthecommonthreadwhichlinksthiseldtogether. 2RelatedResearch viewresearcheortswhichillustratedierentapproacheswithinthatcategory.weconcludeby attempttocategorizecurrentmeta-environmentapproaches.foreachofthecategories,were- Intherestofthispaper,weexaminethetrendforcreatingmeta-environments.First,we Softwareengineeringenvironmentswereinitiallyconstructedasmonolithicsystems,usingaprogramminglanguageastheconstructionmodel.Twoofthemorenotableexamplesofthisapproach environmentconstructionintothefollowingveclasses: ofconstructionandimprovingtheutilityofenvironments.wehavecategorizedtheapproachesto aretheprogrammingsupportenvironmentsforsmalltalk[37]andinterlisp[88].bothenvironments usingthisapproachisgenerallyprohibitiveformostresearchorganizations. supportasinglemethodofsoftwareproduction:interpretive,incrementalprogramdevelopment. anysoftwareproductionmethodandprogramminglanguage,thecostofproductnganenvironment Whilethemonolithicapproachcanbeappliedtoconstructenvironmentswhichsupportvirtually Environmentframeworkssupportasetoflow-levelservicesincludingobjectmanagement, Sincethemonolithicapproach,avarietyofmethodshavebeensuggestedforlesseningthecost 2

3 Customizableenvironmentsprovidehigh-levelcoreenvironmentcapabilitiesandameansof controlmanagementandsometimesuser-interfacemanagement. Processprogrammingprovidesaprogramminglanguageorientedtowardsthedescriptionof Processmodelingprovidesameta-modelwhichcanbeinstantiatedtospecifytheactivities, theenvironment. developers,resources,artifacts,andtheirrelationshipswhichtogetherformtheprocessesof customizingthosecapabilities. andalsotoillustratethemainissueswhichseparateresearcherswithinacategory.mostresearch researcheortsineachcategorywhichservebothtogivefurtherinsightintothebasiccategory Toolintegrationprovidesthemeanstocombinetoolsintoanintegratedsetofenvironment Inthefollowingsections,wefurtherdeneeachofthesecategories.Wealsopresentseveral processesasthebasisofconstructingprocess-drivenenvironments. ample,manyenvironmentframeworksprovidesupportfortoolintegration.nonetheless,wehave categorizedandpresentedtheseeortsinordertoillustratethemeta-environmenttrendasawhole. eortsinmeta-environmentsactuallycombinetechnologyfrommorethanonecategory.forex- capabilities. theconceptualenvironmentarchitecturereferencemodel(cearm)[70],theecmareference considerableattentionisbeingdirectedtothedenitionofthekindsofserviceswhichenvironment frameworksshouldaddress.muchofthisworkhasbeendonebycreatingreferencemodelsincluding construction.asastartingpointforasurveyofthisresearch,itisagoodideatomentionthat environmentframeworkswhichprovideasetofcomputationalservicesasabasisforenvironment Oneoftherecenttrendsinthecommercialandgovernmentsectorshasbeenthedevelopmentof 2.1Environmentframeworks Model[23],andtheNISTReferenceModel[94].[48]usedoneofthesereferencemodelstosurvey vironmentmanagement[70]andtaskmanagement[23]).theobjectmanagementservices(oms) currentenvironmentframeworkresearch.thissurveyshowedtheusefulnessofareferencemodel portedbyoperatingsystems.thelife-cycleprocessmanagementservices(lcpms)providea provideforpersistentobjectsandrelationshipsasopposedtolesanddirectoriestraditionallysup- asaconceptualframeworkforcomparingthecapabilitiesofframeworks.muchofthissectionis ontheoperatingsystemprocess.however,thelcpmscombinesoperatingsystemprocesseswith User-InterfaceManagementServices,andLife-cycleProcessManagementServices(alsocalledEn- derivedfromthatstudy. additionalmodelingservicestoprovideamorepowerfulcontrolmechanism.theuser-interface meansforenactingchangeuponthecurrentstateoflife-cycleobjects.mostlcpmsarebased ThesereferencemodelssuggestthatframeworksshouldaddressObjectManagementServices, ManagementServices(UIMS)providebasicmechanismsfordeninguser-interfacesandassociating objectsgraphicallydepictedwithobjectsandactionswithintheenvironment. formodelingdata,control,anduser-interface.whileothermeta-environmentapproachesrequire, Thesereferencemodelssuggestthatenvironmentframeworksmustprovideconstructionmodels 3

4 forexample,somekindoftranslationofalanguageorenvironmentspecicationintoanenvironment,asimilartransformationoftheframework'smodelsisnotneededsincetheframeworkmodels areusedasthearchitecturalbasisoftheenvironment.theexamplesthatwepresentnextshowa varietyofdataandcontrolmodels. designedtoassistinbuildingspesindependentoftools,methodology,orlanguages.itprovides agenericoperatingsystem,anobject-orientedomsandamacintosh-likeuserinterface.the classeswhichgivethedatabaseitsform.theomsusestheconceptofgenericmessagestoinvoke SoftwareBackPlane'sOMSprovidesanobject-orientedsoftwareinterfaceandasetofpredened allobjects.thisapproachallowsuserstoinvokesimilartoolsusingidenticalmessages. methodsfornew/free,open/close,checkin/checkout,andotherswhichareapplicabletovirtually AthertonTechnology'sSoftwareBackPlane[68]isanintegrationandportabilityframework ingnewclassesorattachingexistingtoolstopreviouslydenedclassesasmethods.toolscreated withoutusingthesoftwarebackplaneasitspersistencemechanismstoretheirdatausingthenativeoperatingsystem.translationoftheirdataandrehostingtothesoftwarebackplanecanbe andtoolinvocationoverthoseobjects. calledthe\environmentcustomizationplan".thisprocesssuggeststhecreationofuser-dened accomplishedbycreatingamethodwhichdoesbothatranslationfromaleintoasetofobjects Sometoolintegrationisaddressedthroughtheobject-orientedintegrationtechniquesfordenorientedOMSasitscornerstone.ItlackssomeoftheintegrationtechniquespresentintheSoftware methodsasaformofprocessprogramming,tooldenition,datadenition,anduser/roledenition. Backplane.Italsolacksaplanforusingobject-orientedtechnologytoinstantiateanenvironment. Athertonhasalsoprovidedahigh-levelspecicationofanenvironmentconstructionprocess ofdefense.cais-aisasetofadainterfaceswhicharedesignedtoactlikeahigh-levelvirtual STD-1838A,underthecontroloftheAdaJointProgramOce(AJPO)withintheU.S.Department operatingsystem.itprovidesanobjectmanagementsystem(oms)andprocesscontrolbasedon theoms.theomsisadistributeddatabaseprovidinganodemodelwhichissimilarinavorto Gaia[90]embodiesanapproachsimilartotheSoftwareBackplanebyprovidinganobject- formalizethestructuresandcapabilitiesoftheoms.processesincais-aformatreeofparentchildprocesses.allprocessinformationiskeptintheoms.processescancommunicatethrough anentity-relationship-attribute(era)modelwithtypeinheritance.thenodemodelisusedto CAIS-A[60,18,71],thelatestversionofCAIS,isdenedinthemilitarystandardreportMIL- SystemisadistributeddatabasebasedonanERAmodelwithmultipletypeinheritance.The consistsofsoftwareinterfacestoservicesofanoms,lcpms,anduims.theobjectmanagement canbeusedasabasisforintegratingtoolsaspartofthedevelopmentofanspe.thepctepti specialoms-basedqueues. objecttypesaremodeledbyasingleoverallschemawhichisactuallycomprisedofasetofpossibly overlappingschemadenitionsets(sds).pctemodelsthestaticcontextofprocesseswhichare messagequeues,pipesandsignals.monitoringofprocessexecutionisalsoavailable.pctehas usedtocontrolprocessinvocation.inter-processcommunicationisachievedthroughtheoms, ThePortableCommonToolEnvironment(PCTE)[89]isaPublicToolInterface(PTI)which denedasetofuser-interfacemanagementprimitives,aswellasextensionstosupportproduction ofreal-timesoftwarethroughthepcte+andpactversionsofpcte. agement,congurationmanagement,versionmanagement,distribution,environmentmanagement, integrationfacility.nseisprimarilyaunixenvironmentwithadditionalsupportforobjectman- TheSunNetworkSoftwareEnvironment(NSE)[1]isanetwork-basedobjectmanagerandtool 4

5 targetgeneration,andenvironmentfront-ends.theobjectmanagerisorientedaroundaspecic viewofversionandcongurationcontrolbasedonanoptimisticconcurrencycontrolmechanism. ToolTalkhasbeenintroducedtosupportthiscapability ToolsareintegratedintoNSEbyusingNSEtocontroltheirobjects(les)andbyaddingthetools tothenseenvironmentfront-end.morerecently,anobject-basedtoolintegrationfacilitycalled CAIS,andtheSoftwareBackPlane.Itprovidesnoextensibilityofthebaseclasses.Itdoessupport anextensiontounixprocessmanagementbyallowingtriggersassociatedwithnsecommandsto performsomeoftheenvironmenttasks. commondatabase,asetofcommonschemata,andtools.thecommonschemataandtoolsare designedtosupportamil-std2167amodelfordocumentingthesoftwareproductionlife-cycle. The2167Amodelisbasedonthewaterfallmodelofsoftwareproductionbasedprimarilyonthe TheNSEobjectmanagerisnotageneralpurposeobjectmanagerinthesameveinasPCTE, specicationofalternativeschemataandalternatelife-cycles. ofadaptationandextensionofenvironments.rdpe3usesanextendedobject-oriented,negrainedprogrammingparadigmtorepresentprogramfragments.thus,rdpe3focusesonasmaller databaseschemabasedontheentity-relationshipmodel.whilethealmaenvironmenthascapa- integrationschemethanthosesuggestedbyotherframeworks,oneinwhichthefunctionofthe componentsizeascomparedtopcte,cais-a,etc.furthermore,rdpe3suggestsadierent integratedcomponentsmustbeaccessible. RDPE3[65]isaprogrammingenvironmentwhichisprimarilyorientedaroundthesupport productionofdocumentsaftereachstepinthelife-cycle.theslcseframeworkalsosupports TheSoftwareLife-CycleSupportEnvironment(SLCSE)[84]isaframeworkwhichprovidesa bilitiessimilartootherframeworks,itspecicallypresentsaplanfortheuseoftheframeworkas bothameta-environmentandasoftwareproductionenvironment. softwareserviceswhichcanintegratemultipledata,control,presentation,andprocessmodels thatcanspanadistributedwide-areanetwork[77].thedsfinfrastructureprovidesadistributed hypertext(dht)frameworktointegrateheterogeneoussoftwareobjectrepositories(e.g.,thosewith TheALMA[55]genericenvironmentprovidesthecapabilitytodenealife-cyclesupport dierentdatamodels)[63]withforwardandreversesoftwareengineeringtools[16],graph-based editorsanduserinterfaces[49],process-drivenuserinterfaceswithpartiallyordertoolinvocation sequences[59],andaknowledge-basedprocessmodelingandsimulationenvironment[58].using thesemechanismsandcomponents,itispossibletosemi-automaticallygeneratemultirole,processdrivensoftwareproductionenvironmentsforahierarchyofconcurrentproductionprocesses[31,59]. TheDistributedSystemFactory(DSF)projectisdevelopingamultilayerinfrastructureof whichisanabstractcommunicationchannelhidingdistributionandsupportingtheexchangeof dataandcontrolinformationusingabstractdatatypeinterfaces.user-interactioncomponents (UIC)andservicecomponents(SC)communicateacrosstheSWB.UIC,whichhavenopersistent atthedevelopmentofanintegrationframeworkforameta-environmentthatcanaccomodatethe accordingtoaprocessmeta-model[2].theheartoftheesfarchitectureisasoftwarebus(swb), interoperationofvarioustoolsandtheinteractionsofpeopleworkingtogetherwiththesetools data,communicatewiththeuserandmakerequestsonservicecomponentsacrosstheswb.sc TheEUREKASoftwareFactory(ESF)[28]isalarge-scalepan-Europeanresearcheortaiming environments. maynothaveauser-interface.oneuicandonesctakentogetherareessentiallyatoolincurrent TheESFkernel,K/2r[2],isnottiedtotheuseofacentralOMSasthebasisofintegration. 5

6 Rather,theESFprojectusesprocessmodelsasthebasisoftoolintegration,althoughdierent DSFprojectssharemanycommongoals,althoughtheirapproachesdier. construction.ingeneral,environmentframeworksareintendedtomaintainindependencefromany wareproductionenvironments.accesstoanimplementationoftheseservicesassistsenvironment schemes[19,30]andmodelingformalisms[21,27]arebeinginvestigated.inthisway,theesfand particularsoftwareproductionmethod.whileenvironmentframeworksprovidesomesupportto environmentconstruction,theservicestheyprovidearegenerallylow-levelfunctions.thereisa environment. considerablegapbetweentheseservicesandtheservicesprovidedbyafullsoftwareproduction Eachoftheseenvironmentframeworksprovidesserviceswhichareneededinvirtuallyallsoft- K/2rsuggestadatamodelbasedontheERorobject-basedmodel,andacontrolmodelbasedon andcontrol.theextendederacampwithpcte,cais-a,slcse,alma,dsf-dht,andesf- conceptswhicharesimilartooperatingsystemprocesses. 2.2Customizableenvironments provide.theobject-orientedcampwithathertonandgaiasuggestasinglemodelforbothdata Existingenvironmentframeworksseemtobesplitonthekindofdataandcontrolmodelsto directededitorgenerators[16,64,76],orextensiblegrapheditors[47,69,79]. theapproachusedinmosttoolgenerators,suchasthoseusedforparsergenerators[92],language- thencombinedwiththecorecapabilitiestoformanenvironment.thisapproachisverysimilarto allowstheusertospecifyasetofextensionsorchangestothecorecapabilities.thisspecicationis anddierentcorecapabilities.theconstructionmethodprovidedbyacustomizableenvironment capabilities.dierentcustomizableenvironmentswillprovidedierentmethodsofcustomization Customizableenvironmentsarebasedontheexistenceofahigh-level,xedcoreofservicesor todescribeonlyasmallportionoftheentireenvironment.theremainderoftheenvironmentisxed willxtheprocesssupportedbytheenvironment,butwillallowparticularpartsoftheprocessto lessgenerality.inotherwords,customizableenvironmentswillsupportamodelwhichcanbeused byassumptionsbuiltintothecustomizableenvironment.inparticular,customizableenvironments besubsequentlymodied. Customizableenvironmentsdierfromframeworksinthattheytradeeaseofinstantiationfor tree,mentorallowstheextensionoftheenvironment. syntaxtreesinspecializedlanguages.byallowingarbitraryannotationsofnodesinthesyntax turededitors.thesecustomizableenvironmentsprovideaconstructionmodelwhichcanbeused asthecommoninformationbase.thissyntaxtreecanbeannotatedbymeansofotherabstract todescribethegrammarsforthelanguageswhichwillbemanipulatedintheenvironment.the programmingenvironment[22]isfoundedonanabstractsyntaxtreerepresentationoftheprogram xedpartoftheenvironmentistheprocessofusingaseriesofeditors.forexample,thementor Severalresearchershavedevelopedcustomizableenvironmentscenteredaroundtheuseofstruc- theyedit,and(b)theattributesoractionroutineswhichsupportincrementalsemanticchecking. GANDALFalsoprovidesforthespecicationofcommandswhichinvokeexternaltoolsintegrated aroundcentralizedparsetreerepresentations,whilesoftmanprovidesfortheintegrationof editors.editorsarecustomizedthroughthespecicationof(a)thegrammarsofthelanguageswhich structure/texteditorswhichallowanenvironmenttobeconstructedasasuiteoftightlyintegrated GANDALF[64],theSynthesizerGenerator[76],andSOFTMAN[16]providecustomizable 6

7 encodeprocessinformationaswellassyntaxinformation.thegrammarisusedbytriadto constructvariousportionsoftheenvironmentincludingasyntax-directededitor. driventoolsdesignedtooperateoveranextendibleattributegrammar.thisgrammarisusedto basedornotation-basedmeta-programmingenvironments.ameta-programmingenvironmentis generatedmultilanguageeditorswithanoms. anenvironmentwhichassistsinthecreationofparsersandrelatedtoolswhichmanipulatea particularlanguage.eachgeneratoracceptsthespecicationofalanguage,thenassemblesa DRACO[62],Popart[92],GEM[38],KIDS[78],andCentaur[53]aregeneratorsofgrammar- TRIAD[51]isacustomizableenvironmentwhichsupportsasetofform-based,methodology- [4]andagenericprocessenginedevelopedatUSC/ISI[5],whichaccomodatesthegenerationofrulebasedprogrammingandtransformationalimplementationenvironments.TheDRACOandKIDS environmentsprovidesimilarcapabilities,althoughtheylackintegrationwithaprocessengine. However,DRACOalsosupportstheintegrationandcompositionofreusablecomponentsortools, asdescribedlater. rules,orannotationsfordraco,popart,andkids,or(b)algebraicandsyntacticspecication supportthedevelopmentofdomainlanguagedenitionsusingeither(a)patterns,transformations, formalismsforcentaur.inaddition,popartisusedinconjunctionwithcommonlispframework aprograminthemanipulatedlanguage.draco,popart,kids,andcentauraredesignedto libraryofroutineswhichcanbeusedtooperateoveraparsetreeorsimilarinternalformof structureeditorsinterfacedtoaconstraint-basedoms.thecombinationofthetoolsandtheobject onthespecicationoftheformalattributesoflife-cycleobjectsandspecicationoftoolswhich operateontheseobjects.thus,thespecicationreferstoobjectsbeyondthosedirectlytiedtothe programminglanguage.however,theprimarytoolsinasoftmanenvironmentarecustomizable developmentandvericationacrosslife-cycleactivityboundaries.itallowscustomizationbased specicationoftheobjectstobemanipulatedduringasoftwarelife-cycleprocess.thesoftman environment[16]providescorecapabilitieswhichenforceaparticularmodelofincrementalsoftware Anotherapproachtocustomizableenvironmentsistoprovideamodelwhichsupportsthe repositorycanthentrackandverifythecorrectnessattributesofobjectsthathavebeencreatedor supportmultiplesimultaneousprojects. [34].Italsosupportsthespecicationofaprocessmodelwhichdescribestheproductionanduseof modied[14]. formsofgroup-basedorteam-basedinteractionandcommunicationstructureswithinaprojectand thedocumentsbycollaboratingagents.thedocumentformatsandprocessmodelsupportmultiple compositionofhypertext-basedlife-cycledocumentsbasedonthedifsoftwarehypertextsystem structureddocumentationprocess.ishyssupportsthespecicationofthetype,attributes,and META/GA[95]isaLife-CycleSupportSystemgeneratorbasedonthespecicationofthe ISHYS[33]providesaninterfacetoahypertext-basedinformationstoragestructureandtoa formatofinformationwhichmustbeprocessedinthegeneratedenvironment.meta/gageneratedenvironmentssupportaspeciclife-cycleapproachtothecreationofinformationprocessing systems.however,themeta/gauser,theenvironmentconstructor,isabletospecifythetypeof informationwhichwillbeprocessed.thiscustomizableenvironmentattemptstohelpstandardize thetypeofinformationandleavethelife-cycleasgeneralaspossible. andcustomizableenvironments.themodelsprovidedarebasedonaneramodelextendedwith constraints,transformations,andagraphicalinteractionmodel.thesemodelsareusedtodescribe TheMetaviewproject[11,82]takesanapproachthatisahybridofframeworkapproaches 7

8 graph-basedorgraphicsoftwarespecicationnotations.edge[69],tge[49],metaedit[79], thedatamanipulatedbytheenvironmentasawholeandbygenerictools.soboththeenvironment frameworkaswellastoolswhichoperateovertheenvironmentarespeciedusingthismodel. VSF[43,72],andGEDL[47]arerecentexamples.Incontrasttostructured-texteditorsand notationfordescribingtheiconicsyntaxandcompositionsemanticstobesupportedinthetarget userinterfacefunctionality[49,47],andsupportavarietyofobjectmodeling,softwareprocess relatedfunctionalitygeneratedbygandalforsynthesizergenerator,thesegraphicmeta-editors [49,47]andmethodnotations[43,72,79].Eachmeta-editoremploysalanguage-basedspecication providemultiplelayoutsofgraphicinformation[47,69],allowthespecicationorredenitionof Thereisgrowinginterestindevelopingstructure-orlanguage-basededitorsformanipulating editorsthataregeneratedorinstantiated.finally,tge,vsf,andgedlhavespecication-level andenvironments,suchassoftman'suseoftge-basedgrapheditors[16,77].subsequently, interfaceswhichallowthemortheirderivededitorstobeintegratedwithoneormorerepositories thisprovidesanotherdimensionfortheextensionofresultingmeta-environments. ofconstructinghighfunctionalityenvironments.however,mostcustomizableenvironmentshave lessenedtheburdenofenvironmentconstructionbyadoptingaparticularapproachtosoftware processmodelsthusrepresentanalternativetothissituation. development.thismeansthatacustomizableenvironmentmayonlysupportcertainkindsofsoftwareprocessesordevelopmentmethods.environmentscenteredordrivenbysoftwareproduction Overall,theprimaryadvantageofcustomizableenvironmentsisthespeedandrelativeease familyofprocessestheenvironmentsupports.thus,aprocessmodel-basedconstructionmethod mustprovideaprocessmeta-modelasthebasisofimplementingaspeciclife-cyclemodel.instances meta-modelallowstheexecutionofaprocess-centeredenvironment. ofameta-modeldescribeactiveandinactiveobjectsinanenvironment.further,aninstanceofa 2.3ProcessModeling softwareprocesses.aproductionrulehas(1)aprecondition,(2)anactionpartwhichisexecuted thosethatprovideproductionrulesandruleinterpretersasthemeansforspecifyingandenacting Inenvironmentsbasedonprocessmodels,asoftwareprocessmeta-modelisusedtocircumscribethe rulesforalloftheactivitiesoreventswhichtheenvironmentshouldsupport. whenthepreconditionistrue,andpossibly(3)apostconditionwhichbecomestrueoncetheaction isexecuted.environmentconstructionusingthesesystemsconsistsofspecifyingtheproduction MarvelandGENESIS.However,theseeortssuggestaparticularexecutionoftheprocessmodels, PRISM[56],IPSE2.5[91],anditssuccessor,PSS[12],provideprocessmeta-modelssimilarto TheGENESIS(fromUCBerkeley)[73],Marvel[46],andMerlin[27]environmentsareamong whichprovidestheenvironmenttotheuser.intheseenvironments,aprocessmodelexecution facilityservesasthemeansofinvokingtoolsandpresentingchoicestoenvironmentusers. graphicaluser-interface,whichdepictsthepetri-netsandallowsboththespecicationofprocess modelsandtheenactionofprocessmodels. frameworksimilartotheonesdescribedinsubsection2.1.amajorpartofthisprototypeisthe ledtothedevelopmentofaprototypecapableofenactingasoftwareprocessmodelontopofa levelpetri-netrepresentationsofsoftwareprocessmodels[26].themelmacresearcheorthas TheSoftwareDesigner'sAssociate(SDA)project[52]isasoftwaredesignenvironmentinwhich MELMAC[21]isasoftwareprocessmanagementenvironmentbasedontheexecutionofhigh- 8

9 designandthatitusesamodel-basedapproachtothedesignandconstructionofanenvironment. positeactivities,productsandtools.sdaisuniqueinthatitonlyaddressestheearlyphaseof latorusesahierarchicalobject-orientedrepresentationofagentroles,products(orresources),and tasks,whichcanbeeitherpartiallyorderedortriggeredthroughrule-basedmechanisms.modeled environmentformodeling,analyzing,andsimulatingsoftwareproductionprocesses.thearticu- agentscommunicateprocesstaskstatusandresourceavailabilitytooneanotherthroughqueries theexecutableprocessdescriptionsarespeciedasaprocessmodelconsistingofactivities,com- andmessages.thesequeriescanentaildirectordeductiveretrievalofprocessenactmentinformation,ortriggereitherthesymbolicexecutionofnewprocessesorreplayprocessesalreadyenacted. TheDSFprojecthasbeendevelopingandusingtheArticulator[57],whichisaknowledge-based Multipleconcurrentprocessescanbeenactedandagentscaninteractacrossprocesses.Inaddition, intheprocessoccur[58]. theenvironmentmaintainspersistentinformationaboutthestateofenactedprocessesasprocess tofacilitateincrementalprocessreschedulingandreplanningwhenunplannedordynamicchanges transitionsoccur.thisinformationisusedtotracktheexecutionhistoryofplannedactivities,and processpre-orpostconditions,dataobjects,andobjectrepositories,thenprocess-drivensoftware environmentscanbeautomaticallyproduced.inonestudy[59],thesoftmanenvironment[16] interpreter(togethercalledpbi)toprovideaframeworkfordevelopingprocessmodel-drivenenvironments[59].thearticulator,pbi,andanopensoftwareenvironmentorsetofsoftwaretoolscan thebeusedtoconstructandinstantiateprocess-drivensoftwareproductionenvironments.thatis, TheArticulatorhasbeenintegratedwithaprocess-baseduserinterfaceandaprocessmodel processmodelscreatedwiththearticulatorareautomaticallytransformedintoprocessprograms thatcanbeenactedbypbi'sprocessinterpreter.whentheprocessmodelsspecifytoolbindingsto wasusedasthebaseenvironment,andasoftwarelife-cycleprocessmodelthatguidesauserin theirinvocationofsoftmantoolswasdevelopedusingthearticulator.thesoftmanprocess theprocess-baseduserinterfacebystructuringaccesstowhichsoftmantoolscanbeinvoked onthedesignatedobjects.thisinturndependsonthedevelopmentprocesshistoryandprocess modelwasthentransformedandloadedintothepbiprocessinterpreter.thisinterpreterdrives SOFTMANhadtobedisabledandredirectedtothenewprocessinterface,whilethetool-specic interfacesandobjectrepositoryforsoftmanremainedintactandunmodied.withthenew enactmentstatusatthattime.inordertodothis,thepre-existingtop-leveluserinterfacefor PBIinterface,auserispresentedwithavisualrepresentationofthedevelopmentprocesscurrently assignedtothem.userscanthenselectthenextprocesstaskoractiontoperform.inthisway, wecansaythataprocessintegrationinterpreteranduserinterfaceenableknowledge-basedprocessmodelstoguideuserinvocationoftoolswithinasoftwareproductionenvironment,suchas [32]andtheSynerVisionprocessexecutionengine[42]inplaceofPBI.Theresultingcomposite environmentiscalledsmart[31].smartsupportsthemodeling,analysis,enactment,measure- messagesandtoolinvocationsacrossthesoftbenchbms[13],andthatmanipulatedatastoredin ment,andimprovementofsoftwareprocessesutilizingencapsulatedcasetoolsthatcommunicate networkedrepositories.sincesmartcancongurecommerciallyavailablecasetools,andas mostunix-basedcasetoolshavesoftbenchencapsulations,thenthenumberandcongurationof process-basedcaseenvironmentsthatcanbegeneratedusingsmartisverylarge.finally,the TheArticulatorhasalsobeenintegratedwiththeMatisseteamprogrammingenvironment PBI-SOFTMAN[59]. ArticulatorhassimilarlybeenintegratedwiththegenericprocessenginedevelopedatUSC/ISI[5], 9

10 whichsupportstherenementofgenericprocessdescriptionsintoconcreteinstantiationsduring itsenactment.thus,thearticulatorenvironmentsuccessfullydemonstratesthepowerofsoftware processmeta-modelsasabasisforintegratingandinteroperatingindependentlydevelopedtools withingeneratedprocess-drivenenvironments. dynamicchangestoaprocessdescriptionduringitsenactment.however,itdoesnotutilizea design,analysis,andenactmentofsoftwareprocessmodels.itsprocessrepresentationisbased processfaults,asdoesthearticulator. onextendedpetri-nets,andtheenvironmentincludesfunctionalmechanismsforaccommodating processsimulationfacility,nordoesitincludeinferentialmechanismsfordiagnosingandrepairing Last,theSPADEenvironment[6]issimilarinscopetotheArticulatorinthatitsupportsthe 2.4Processprogramming Processprogrammingenvironmentsuseaprogramminglanguagetodescribetheprocessesthat struction.however,wecanviewprocessprogrammingasprocessmodelingwherethemeta-model formthecapabilitiesoftheenvironment.thegoalofprocessprogramming-basedsystemsisto provideahighlyexible,process-orientedenvironmentconstructionmechanism.processprogram- environmentbyexecutingpartsoftheprocess.thearcadiaenvironmentisaprocess-centered isaprogramminglanguage. developmentprojectsconductedbythearcadiaconsortium.likeesf,arcadiacouldalsobe mingdiersfromprocessmodelingintheformofthemeta-modelprovidedforenvironmentcon- whichareexecutedtoformtheenvironment. environment.theformoftheenvironmentwhichtheusersseeiswhollydeterminedbytheprocesses onthecapabilitytoexecuteprocessprograms.inthismanner,usersinteractwithanarcadia-based categorizedasanenvironmentframework,butthearchitectureofthearcadiaframeworkiscentered TheArcadiaResearchProject[87]consistsofacollectionoflooselycoordinatedresearchand UIMSbasedonaverystrongseparationoffunctionalityfrominteraction.TheOMSinArcadiais viewedaspossiblymanydierentobjectmanagerscombinedthroughacommonunderlyingtype OMS,anAda-basedProcessProgrammingLanguage(APPL/A),aMeasurementandEvaluation modelwheredataiscombinedthroughinteroperabilitymechanisms.triton[41]andpgraphite (M&E)system,andaProcessAdministrationSystem.TheUIMSisbasedonChiron[50],anAda [93]aretwoOMSswhichhavebeenusedasabasisofobjectmanagementintheArcadiaproject. APPL/A[86]isaprocessprogramminglanguagewhichconsistsofextensionstoAdathatinclude ArcadiaiscurrentlyacollectionofmanypartiallyintegratedcomponentsincludingaUIMS,an adaptationcanbebuiltupbycreatingprocesseswhichactlikevirtualarchitectures.inother words,aprocesscouldbedenedwhichwouldallowthespecicationofuser-roledenitions.this mechanismwouldnotbepartofthearcadiainfrastructure,butitwouldbepartofthevirtual canbedirectlydenedusingthesoftwareinterfacesprovidedbythearcadiainfrastructure.further hasbeensuggestedasabasisforthespecicationofenvironmentcharacteristics. thenotionofpersistentrelationsassociatedwiththeoms.theprocessadministrationsystemisa environmentcreatedbythedenitionoftheprocesswhichallowsuser-rolespecication. run-timesupportinterfaceforexecutingprocessesbasedonacorporatemetaphor.thismetaphor programminglanguage,adele,todescribeandimplementenactableprocesses.adele-2provides EnvironmentadaptationistheprimaryfocusoftheArcadiaarchitecture.Dataandprocesses Incontrast,theAdele-2environment[61]utilizesaspecial-purposepersistentdatabaseand 10

11 coupling,aswellasactivityandtaskspecication,areallrealizedusingtheadele-2language. supportformultipleworkenvironments(i.e.,tool,policy,andmethodcongurations)thatare gines.eachprovidesaprocessprogramminglanguagebasedontheunixshellcommandlan- gugage.theiruseissimilarinscopetoadele-2,buttheybothlacksupportforapersistent objectstore,otherthantheunderlyinglesystem.however,thesmartenvironment[31]can ProcessWEAVER[29]andSynerVision[42]arecommerciallyavailableprocessexecutionen- coordinatedandcoupledthroughanactivitymanagerandataskmanager.coordinationand attributedwithunixshellcommands,whichcansubsequentlybeexecutedunderuserdirection. semi-automaticallygeneratesynervisionprocessprogramcodeviatransformationsonarticulatorbasedsoftwareprocessmodels[57],whileprocessweaverallowsmodeledprocessstatestobe modelandprogrammingenvironmentcanbedynamicallymodied.thus,object-orientedprocess andsoftwaredevelopmentenvironmentscanbeunitedintoasingleviewinwhichboththeprocess gramminglanguage,andmeta-environmentframeworkwheretheenvironmentdata,control,and programmingseekstoprovideanobject-orientedprocessmodel(ormeta-model),processproming.theideainthesetwoeortsistoshowhowobject-orientedviewsofprocessprogramming presentationmodelsallshareauniformobject-orientedrepresentationandinterpretationscheme. Last,bothOIKOS[3]andOPM[85]proposeobject-orientedapproachestoprocessprogram- Aprimaryconcernforenvironmentcreatorsistheintegrationofexistingtoolsaspartofthe 2.5Toolintegration capabilitiesofanenvironment.becausetoolintegrationprovidestheabilitytoinvokeothertools, thetechnologydescribedinthissectionisoftenappliedineachofthepreviousmeta-environment toolwhichisinchargeofexecutingaprocessmodelandinturninvokesothertools.however, wehavesplittoolintegrationintoaseparatecategorybecausealargebodyofeortshavea constructionapproaches.forexample,aprocessmodel-basedenvironmentcanbebasedonaspecial distinctmodel,transformation,andprocessfromanyofthepreviouscategories.inparticular,tool integrationmeta-environmentsprovideamodelbasedonaninterfacebetweenasetofconnected tools.theexecutionoruseoftheinterfacetothetoolsisthetransformationofthemodelintoan environment. data-exchange,whileothersarestandardswhichaectalldatastorage.theotherpathistobuild technologywhichcanusetoolsdevelopedpriortooroutsideofthestandards.intheremainderof 2.5.1Standards ofstandardswhichtoolsmustuseinordertobeintegrated.somestandardsaremerelystandardsof thissection,wewillconsiderexamplesofbothapproaches. Basicallytwopathstowardseasierintegrationhavebeensuggested.Onepathisthedevelopment promoteintegrationandmaketooldevelopmenteasier. asetofinterfacesthatsupportschema-drivendispatchingofbehavior.atis/cisispresentedin dard(cis),isaproposalforanobject-orientedapproachtotheintegrationoftoolsthatprovides AToolIntegrationStandard(ATIS)[9]anditsmorerecentname,aComponentIntegrationStan- nesasetofclassesandtheirproperties.thismodelisdesignedtoprovideservicestotoolswhich methods.inotherwords,atis/cisproposesaninstanceofanobject-orientedmodelwhichde- termsofahierarchythatspeciesandinterrelatesabstractdatatypes,theirproperties,andtheir 11

12 asanapproachtorepresentingdata.informationisstoredattwolevels,thedenitionlevelandthe Subcommittee21WorkingGroup3).TheIRDS/ISOusesamodelsimilartotherelationalmodel usinganeramodel.instancesofthemeta-modelaremodelswhichdescribedata.irdsallows thetypesofentities,relationships,andattributes. StandardsOrganization,InternationalElectotechnicalCommissionJointTechnicalCommittee1/ accesstoschemadenitionsthroughaccesstoinstancesofmeta-entities.themeta-entitiesdene TheIRDS/ISOistheIRDSRapporteurGroupoftheISO/IECJTC1/SC21WG3(International TheIRDS[39]isanANSIStandard(ANSIX3.138).TheIRDSstandarddenesameta-model object-orientedmodel. theconceptofameta-meta-model.inordertodescribetheconceptualmodelsforeachofthesedomains,amodel(i.e.,themeta-meta-model)whichcandescribedatamodelsfordierentapplication domainswasdeveloped.themeta-meta-modelissimilarinformtoanentity-relation-attribute (ERA)model.VariousproposalsforhowtobestimplementCDIF-baseddatatransformations, however,seemtofocusonbatchedmonolithictransformationoflargedatasets.incontrast,the DHTapproachnotedearlieralsoincorporatesmodelingformalismsimilarinpowertoameta-meta- CDIF[24]isadenitionofacommondatatransferformatwhichsupportsmanydatamodels IRDlevel.Thedenitionleveldenesthetablesandthefunctionswhichmanipulatethetables. TheIRDlevelcontainstheapplicationdata.Thisisanalogoustoclassandinstancelevelsofan andthetransferofdatabetweencasetoolsorframeworks.thecdifapproachisbasedupon agementserviceusingapersistentprogramminglanguage,whilecdiflackssuchaserviceand programminglanguage. datamodel,butdoesnotrequiretransformationofdatasetstosupportaccesstoheterogeneous datarepositories[63].inaddition,dhtimplementsapersistenthypertext-basedobjectman- theplatform.theseinterconnectionsconsistofthedatabasemanager,communicationnetwork tool-integrationstandardbeingdevelopedbytheieeecomputersociety'staskforceonpro- whichmustbesupportedbytheplatformandbythetoolstoeectivelyintegratethetoolsinto organizationandtool-to-platforminterconnections,andalanguageforthetransferofdatabetween tools.thetooltoorganizationinterconnectiondenesroles,life-cyclephases,andsupportelements fessionalcomputingtools.theapproachtakeninp1175istodenereferencemodelsfortool-to- whichrelatetoatool.thetooltoplatforminterconnectiondescribesvariousinterconnections TheP1175referencemodelforinterconnectionsbetweencomputingsystemtools[44]isa informationsystemsvendors,users,andresearchorganizationswithdiversebackgrounds.thebasic technicalapproachbeingfollowedinomgisanobject-orientedlayerofserviceswhichexistsabove variousimplementationsofobjectmanagers,user-interfacefacilities,andenvironmentmanagers. Manager,O/SServiceManager,andtheUserInterfaceManagerinterfaces. Thislayerdenesasetofnetworktransparentprotocolsformessage-orientedcommonservice requests. TheObjectManagementGroup(OMG)[81]isaninternationalorganizationofmorethan50 asthebasisforsharingproductdatabasesandarchiving. throughoutthelife-cycleofaproduct.thisrepresentationissuitableforneutralleexchangeand ofhardwareandsoftwareplatforms,dataformats,tools,site-specicpoliciesandmethodologies, thedevelopmentandimplementationofstep(standardfortheexchangeofproductmodeldata -ISOTC184/SC4).STEPisaneutralmechanismcapableofcompletelyrepresentingproductdata TheEngineeringInformationSystem(EIS)[54]isavastundertakingaddressingheterogeneity TheProductDataExchangeusingSTEP(PDES)isaUSorganizationalactivitythatsupports 12

13 linesforserviceswhichenableandaccelerateatrendtowarduniformengineeringenvironments setoffunctionalandotherrequirements.thisapproachconsistsofproposedstandardsandguide- andinterfacesprimarilyorientedaroundthecomputer-aidedengineering(cae)domain.within controlthedataandactivitiesoftheengineeringprocess.theframeworkiscomposedofanoms, andinformationexchange.theeisframeworkcontainsautomatedserviceswhichsupportand thecaecommunity,theeisprogramisintendedtoproduceaconsolidatedapproachtoabroad ApplicationObjectModel(AOM),andEngineeringEnvironmentServices(EES).TheOMSis UIMSdesignnotonlyconcentratesoninterfacesforinteractiveEISapplicationsandtooladapters, addressescongurationmanagement,accesscontrol,audittrails,backupandarchival,inter-eis thatsupporttheengineeringandadministrationprocessesbuiltontopoftheaom.theees exchange,userenvironmentservices,e.g.,login,andruleprocessing(data-driventriggers).the UIMSisafamilyofguidelinesandcandidatestandardsforaninterfacetoaCAEsystem.The object-orientedcapabilities.theeesisalargecollectionoftypes,operations,anddefaultpolicies anddataaccessfacilities.theaomusestheomstocreatehigher-levelconstructswhichprovide composedofameta-model,schemamanagement,executioncontrol,objectidenticationsupport, butalsoprovidesinterfacesfortyinginexternaltools. usethestandard.atthispoint,mostofthesestandardsareunaccepted,eitherbythenational orinternationalstandardsorganizations,e.g.,iso,nist,orbysoftwaretoolvendors.oneofthe haveonlypresentedasmallsubsettogivesomeavorofthisapproach.theieeep1175eort problemsfacingstandardizationeortsisthevastnumberwhichapplytotoolintegration.we citesaroundtwohundredstandardseorts,manyofwhichoverlaporcompetewithoneanother. cannotbebroughtuptoparwithmoststandardseorts.whilesomestandardsdoaddressthis Anystandardizationapproachtotoolintegrationwillworkonlyifasignicantnumberoftools problembyconsideringapproachestodatatransferwhichdonotrequirechangingstorageformats knowledgeoftheirtechnology. varioustechnologieswhichaddressissuessimilartothestandardseorts,butdonotassumeprior ofexistingtools,manyofthestandardsfallshortinthisarea.thefollowingsectionconsiders Anotherproblemfacingstandardizationeortsisthelargenumberofexistingtoolswhich fallsshortofthekindoftoolintegrationthatothereortshavedemonstrated. ponentsortoolsaccordingtoaspecicproblemareaordomain.dracousesadomainlanguage throughstandardtypelessi/ofacilities.howeverusefulthissimplepipingmechanismmaybe,it thecombinationoftoolsintolargertoolsthroughtheinterconnectionoftooloutputstotoolinputs ToolintegrationenvironmentsbeganwiththeUnixoperatingsystem.TheUnixpipefacilityallows 2.5.2Integrationtechnologies glereusablecomponentcorrespondsdirectlytoeachobjectandoperationinthedomainlanguage. Giventhedomainofsoftwareproductionenvironmentconstruction,DRACOeectivelyprovidesa fordescribingprogramsineachdomain.statementsofprogramsinthesedomainlanguagesare thenoptimizedbysource-to-sourceprogramtransformationsandrenedintootherdomains.asin- toolcompositionlanguagebasedonamoduleinterconnectionlanguageparadigm.genesis(from UTAustin)[8]issimilarinpurposetoDRACO,butspecializedtoadomainforconstructingand DRACO[62]isanapproachtotheconstructionofsoftwarebyorganizingreusablesoftwarecom- generatingofspecial-purposedatabasemanagementsystems. Toolpack[67],andlaterOdin[17],supporttheconstructionofanenvironmentbasedonthe 13

14 integratedthroughtheuseofodincanbethoughtofascollectionsoftoolswhicharesatellites specicationofsoftwareobjects,tools,andrelationshipsbetweenobjectsandtools.environments itsactionsviathebms.thebmsusesabroadcastparadigmviathesoftwarebuswhichisdifferentfromthepoint-to-pointparadigmoeredbyobject-orientedsystems.thebroadcastnature amotif-baseduser-interface,theencapsulator[20],andsomeintegratedcasetools.inthehp eralcomponentsincludingthebroadcastmessageserver(bms)thatfunctionsasasoftwarebus, predecessorstothearcadiaenvironmentdescribedearlier. aroundalargestructuredrepositoryofsoftwaredata.bothtoolpackandodinareancestral integrationmodel,eachtoolmakeschangestoglobalinformationandinformsothertoolsabout ofthebmscommunicationallowsthesetoftoolsmanagedbyabmsandinterestedinaparticularmessagetobeextendedwithoutrequiringanychangeinthetoolsthatsendthemessages. TheHewlett-PackardSoftBenchproduct[13]isatoolintegrationframeworkcomprisedofsev- denitionisveryprimitiveandwillbetoolimitedforenvironmentsconsistingofaverylargenumberoftools.a\multi-cast"messagingparadigmwhichtransmitsstronglytypedmessagesmay describesauser-interfaceandcorrespondingcommunicationacrossthebms.thecommunication TheEncapsulator[20]providesameansofintegratingtoolsintotheHPSoftBenchuser-interface informationconsistsofmessageswhichitwillrespondtoandmessagesitwillgenerateinresponse touser-interfaceevents.themessagemodel[45]whichissuggestedasabasisoftheenvironment tionmechanismshavebeenproposedasthebasisofanew\standard"foropentoolintegration, provideanalternative.accordingly,acombinationofsoftbenchandsun'stooltalktoolintegra- andbms.theencapsulationconsistsoftheencapsulationdescriptionlanguage(edl)which alldatathroughthemessageserverratherthanrelyingonacommondatabase.additionally,field suppliesaneditorwhichprovidesconsistentaccesstosourcecodeinmultiplecontextsandasetof mechanismcalledselectivebroadcasting.fieldhasextendedthehpsoftbenchapproachbypassing aspartofthecommondevelopmentenvironment(cde)nowbeinginvestigatedbytheopen anismbasedonpolicies.policiesarerulesthatdeterminehowandwhentoolsareinvoked.this analysistools. SoftwareFoundation(OSF). approachrepresentsahybridbetweenprocessmodelingmechanismsandframeworks. Forest[35]hasextendedtheFieldcommunicationmechanismwithanadditionaldecisionmech- Field[74,75]providesanintegrationframeworkverysimilartotheBMSusingacommunication theuseofatoolintegrationtechnologybasedonthemoduleinterconnectionlanguageratherthan terconnectionlanguageandaspecicationoftheleveloftrade-obetweenevolutionsupportand lutionenvironment.toolsandapplicationsareprogramswritteninanextensionofcommonlisp calledap5.ap5providesapersistentvirtualdatabaseofrelations,objects,andrules.therules connecttoolsthroughtriggeringupondetectionofchangestodataorcallingprocedures. eciency.thisapproachisdierentfromthepreviousapproachesinthatitprimarilyaddresses TheScorpionMeta-Environment[80]usesaspecicationoftooltopologyusingamodulein- TheCommonLispFramework(CLF)[4]isanincrementalintegration,development,andevo- addressingtheintegrationtechnologyitself. stratedintheclfandodin.matisseprovidesamultiuserprogrammingsupportenvironment whereuserfunctionalityanddataobjectrepresentationaremanagedbyanintepreted,rule-based, persistentprogramminglanguage.inthismanner,sharedobjectsorsoftwarecomponentscan becachedintoauser'slocaladdressspacefromanetworkedobjectrepository,torealizeauser- Last,theMatisseteamprogrammingenvironment[32]buildsuponconceptspreviouslydemon- 14

15 otherenvironmentconstructionmethodsinordertosupporttheconstructionofafullenvironment. extendedorcombinedwithenvironmentframeworksorprocesssupporttechnologies. Thus,itshouldbenosurprisetondthatmanyofthesetoolintegrationmechanismsarebeing environmentconstruction.generally,toolintegrationmethodsmustbeusedinconjunctionwith congurableoruser-extendedworkspace. usuallybasedonalimitedcontrolpolicy,theyrepresentonlyapartialsolutiontotheproblemof externallydevelopedtoolsintoanenvironment.however,becausetoolintegrationconstructionis Overall,toolintegrationconstructionmethodsaddresstheimportantproblemsofintegrating 3TheMeta-EnvironmentProblem questionofwhatrequirementsmustameta-environmentaddress. ondieringapproaches.giventhesevariousapproaches,wewillnowconsiderthemoregeneral andtransformations.forsomeofthecategories,wehaveshownsubcategorieswhicharisebased InTable1,webrieysummarizethecategoriesofmeta-environmentsintermsoftheirmodels 2.6Summaryofmeta-environmentresearch functionalrequirementswhichformthecommonthread. environments[66,82,83].thatis,ameta-environmentmustbecapableofproducingenvironments thistrend,wewillattempttogivefurtherinsightintotheproblemareaand,inparticular,tothe thatallattempttoaddressproblemsassociatedwithenvironmentconstruction.thus,topresent similar,theproblemstheyaddressare.inparticular,thecommonthreadamongtheseeortsis Intheprevioussection,wepresentedavarietyofapproachestoloweringthecostandimproving theeciencyofenvironmentconstruction.whilewehavefoundthattheapproachestakenarenot technology.theseroles,processes,andrelatedresearchareusedasthebasisoftherequirements presentedinthenextsection. buildersmustplayandtheprocessestheymustperformwhicharethebasisformeta-environment whichsatisfytheserequirements.inthissection,wewillrstpresentthekindsofrolesenvironment Considerableworkhasbeendoneintheareaofdeningtherequirementsforsoftwareproduction technologyistolookatthevariousrolesplayedbyenvironmentbuilders.acompletemetaenvironmentprocessmustaccountfortherolesoftheenvironmentintegrator,componentbuilder, andcomponentmodelmanageramongothers. Oneofthebestwaystounderstandtheproblemswhicharetobeaddressedbymeta-environment 3.1Meta-environmentroles Inparticular,developersactinginthisroleutilizemeta-environmenttechnologyforenvironment lingtheassociatedconstructionofanenvironment.thisrolehasbeenthefocusofthispapersofar. construction,buildaspecicationoftheenvironmentintermsofthemeta-environment'sconstructionmodel,andthengenerateandrenethespeciedenvironment.ingeneral,thegenerationpart theenvironment'scharacteristicsintermsoftheconstructionmodelisademandoftenrequiring oftheprocessisanautomated,oratleastsemi-automated,task.however,thetaskofspecifying Theenvironmentintegratorisresponsibleforcreatinganenvironmentspecicationandcontrol- 15

16 Category FrameworksERAdatamodel, Model Process-based Transformation PCTE,CAIS,SLCSE, Examples CustomizableGrammar-based Controlmodel Object-oriented dataandcontrol Language-oriented Useddirectly environmentgeneratedsynthesizergenerator Atherton,Gaia,RDPE3 Mentor,GANDALF, ALMA,DHT,ESFK/2r Process modeling Processmeta-modelExecuteddirectly Life-cycleobjects GeneratesenvironmentSoftman,ISHYS, whichisspecictothemeta/ga,metaview informationdomain ESF,Genesis,Marvel, Merlin,PRISM, TRIAD,GEM,EDGE, TGE,VSF,GEDL programmingprocess-orientedprogramminglanguagecompiledtogenerate environment SDA, Articulator,PBI-Softman, Tool IPSE2.5,PSS,MELMAC, integration StandardsandtoolToolsuseddirectly Toolintegration ATIS,IRDS,IRDS/ISO, SPADE,SMART technologyandtoolaccordingtotoolaccordingtotool CDIF,P1175,OMG, PDES,EIS Arcadia,Adele-2,OIKOS, interface interface Odin,HPSoftBench, Unix,DRACO,Toolpack, Field,Forest,CLF, OPM,ProcessWEAVER, Scorpion,PBI,Matisse SynerVision Table1:Summaryofmeta-environmentresearch 16

17 Instead,theenvironmentintegratorreliesonexistingframeworks,processexecutionmechanisms, theenvironmentintegratortobeasoftwareprocessarchitect,toolintegrator,datamodeler,control componentswhichwillbeusedinspes.thisrolehasnotbeenconsideredtothispoint.in general,theenvironmentintegratordoesnotcreatealloftheenvironmentcomponentsfromscratch. responsibleforcreatingthistechnology,aswellastheothersoftwarecomponentswhichmaybe modeler,etc. reusablecomponentrepository,orextracting(andrestructuringifnecessary)candidatecomponents toolintegrationtechnology,generatedoracquiredtools,andschemata.thecomponentbuilderis incorporatedintothem.thismayentailselectingfromexistingcomponentsavailablewithinsome Thecomponentbuilderisresponsibleforcreating,providing,orautomaticallygeneratingnew fromexistingsoftwaresystems[15,59].notethattherecanbemanycomponentbuildersbuilding productswhicharecompletelyincompatible.thefactthattheyassumethesameroledoesnot ponentcharacteristics.presently,themodelsareverysimpleandthedescriptionofcharacteristics implythattheyworktogether.nonetheless,oncethecomponentbuilderhascreatedoracquired isinnaturallanguage.however,asmeta-environmenttechnologybecomesmoreprevalentand environment. anewcomponent,thatcomponentispotentiallyavailableforuseinanenvironmentormeta- sophisticated,therewillbeaneedformoresophisticatedmodelstoallowforautomatedandsemiautomatedselectionofenvironmentcomponentsaspartoftheenvironmentintegrator'srole.an interconnectionformalismsandinteractionprotocols.thus,thecomponentmodelmanagercan emerginglineofresearchhasbeguntoexploreanddevelopsuchmodelsusingmodule/component beseenasamediatorbetweenthecomponentbuilderandtheenvironmentintegrator,wherethe Thecomponentmodelmanagerisresponsibleforthecreationandevolutionofmodelsofcom- modelisthelanguageofdiscoursebetweenthesetworoles. Environmentspecication:Thefundamentalrequirementthatameta-environmentmustsatisfy attempttosatisfy. 3.2Meta-environmentrequirements isthatitshouldbeabletosupporttheconstructionofsoftwareproductionenvironmentsinaccordwiththeirspecications.thisimpliesthataconstructedenvironmentmustsupportdesired Giventheseroles,wewillnowpresentasetofrequirementswhichmeta-environmentsmust softwareproductionmethodsandtheprocesswhichcontrolstheapplicationofthesemethods. Furthermore,aconstructedenvironmentmusthavethecharacteristicsofa\good"environment: datingoneormoreoperatingsystems,computinghardwareplatformsandnetworkcommunication itmustbefast,provideahighleveloffunctionalityinaconsistentandcoherentmanner,provide aconsistent\lookandfeel"graphicaluserinterface,etc.[66,82,83].ameta-environmentshould process(ormeta-model)shoulddenetheproceduresforcreatinganenvironment. protocols.finally,eitheran(i)empiricallytested,(ii)experience-based,or(iii)analyticallyrobust textualpresentationdisplays,andmultipleprocessmodeldescriptionsornotations,whileaccommo- specifydatamodels,datarepositories,toolbindingsandcontrolmessageinvocations,graphicand provideaconstructionmodelabletoexpresspoliciesormethodsfordealingwithsecurity,integrity, reuse,process,etc.furthermore,theconstructionmodelshouldbegeneralenoughtoexpressany Easeofuse:Theconstructionmethodsupportedbyameta-environmentshouldbeeasytousein ofthemechanismswhichcanbechosenwithinanyofthesecategories.thisincludestheabilityto 17

18 thefollowingways: Multiplelevelsofsupport.Theusersofameta-environmentarelikelytohavedierentlevels Understandable.Ameta-environmentshouldprovidesupportinunderstandingtheconstructionmodelthroughvisualization,query,andbrowsingofprocess,control,anddatamodel representationsthatwillbeembodiedintheresultingenvironment.inaddition,theprocessbywhichaspecicenvironmentisconstructedshouldbeabletoberecorded,analyzed, specicationswhichprovidesupportforthesemethodsislikelytobeverylarge.ameta- replayed,simulated,recongured,andreused. ofexpertiseindealingwiththemeta-environment.forthisreason,ameta-environment constructors,e.g.,viaprocessprogramming,andeasierinteractionfornonexpertenvironment constructors,e.g.,byspecifyingparametervaluesinaprocessmodel. shouldsupportmultiplelevelsofinteractionwhichgivegreaterpowertoexpertenvironment Selectionassistance.Thenumberofpossiblesoftwareproductionmethodsandenvironment Automaticerrorchecking.Ameta-environmentshouldsupportautomaticerrorcheckingin correspondingenvironmentspecications.meta-environmentsmightincludereusableorextensible\starterkits"[40],orcompleteworkingexamplesofthekindsofenvironmentsthaenvironmentshouldassistusersintheselectionofdesiredsoftwareproductionmethodsand canbereadilyproduced. Evolutionsupport.Alterationsarelikelytooccurinresponsetoevolutioninboththeneedsof aprojectandavailabletechnology.boththeenvironmentscreatedbyameta-environmentand this.inaddition,mechanismsforanalyzing,simulating,replaying,orrepairingenvironment specicationsorprocessmodelswillbehelpful. ordertopreventthecreationofenvironmentswithsignicantbugsincompilation,execution, themeta-environmentsthemselvesmustbecapableofsupportingevolution.ameta-environment orexecutionsemantics.language-directedtextorgraphiceditorsthatcandetectandprevent shouldsupportevolutioninthefollowingways: theentryofsyntacticallyorsemanticallyincorrectdescriptionsaretypicaltoolstosupport Incrementalspecication.Itislikelythatonlypartofthecompleteenvironmentspecication Datacontinuity.Changestoenvironmentsarelikelytoberequiredduringthelifetimeofthe Environmentversions.Astheenvironmentevolves,itisimportanttocontrolitsevolutionina incrementalconstructionofanenvironmentbasedonpartialspecications. softwareproductionenvironment. willbeavailableorknownatthestartofaproject.ameta-environmentshouldsupportthe lossofprojectdataduringtheevolutionofenvironmentspecicationsandthecorresponding projectwhichanenvironmentsupports.therefore,ameta-environmentshouldpreventthe Openfornewtechnology.Whennewtechnologysuchasbettertools,frameworks,userinterfaces,ormethodsbecomesavailable,themeta-environmentandtheenvironmentsconstructed bythemeta-environmentshouldbeabletotakeadvantageofthisnewtechnology.thisrequirementaectsboththeformoftheenvironmentsandthemeta-environmentitself.the controloverenvironmentspecications. systematicmanner.therefore,ameta-environmentshouldsupportversionandconguration 18

19 AdoptExistingCapabilities.Oneoftheprimarymeansformakingsignicantgainsinenvironment constructioncapabilitiesistoadoptexistingtechnology,suchascurrentlyavailabletools,frameworks,anduserinterfaces.ameta-environmentshouldsupporttheuseofexistingtechnologyries,andprocessmodelingnotations. integrateandinteroperateheterogeneoussoftwaredataobjects,components,tools,reposito- shouldbeabletomakethenewtechnologyavailabletoenvironmentspecications,andthus environmentshouldbeopensuchthatnewtechnologycanbeincluded.ameta-environment whereappropriate,inordertoleveragethepoweroftheconstructionmethodandcorrespondingly, theconstructedenvironments.ameta-environmentshouldalsosupport,wherepossible,theuseof cationgenerators.environmentcapabilitygeneratorsdonothavethesamecharacteristicsasthe 4Conclusions power. environmentcapabilitygeneratorsortool-buildingtools,suchaseditorgeneratorsorotherappli- Researchonmeta-environmentsforsoftwareproductionisfollowinganumberofalternativepaths, capabilitiesthemselves,butmeta-environmentsshouldprovideaneectivemeansofutilizingthis representingafocusoneitherenvironmentframeworks,customizableenvironments,processmodplementaryalternativestothechallengingproblemofhowtorapidlyproducestandardizedorcustomizedenvironmentsforengineeringsoftwareapplications.clearly,noonepath,noranysingleling,processprogramming,ortoolintegration.thesepathsrepresentbothcompetingandcomtherdevelopmentofmeta-environmentsisanimportantsteppingstoneinthecreationofeective mechanismsacrosstheseeorts.accordingly,wethinkthatfurtherstudyinthiseldandfur- Further,wemayexpecttoseeatrendtowardneworincreasedcombinationoftechniquesand clearthatmostoftheseeortscombinetechniquesandmechanismsemployedinothercategories. meta-environmentarchitecture,representsthebestchoiceinallcircumstances. shouldbesatisedoraddressedbymeta-environmentsinthetimeahead.theserequirements Finally,wehaveattemptedtosummarizeandsynthesizeanemergingsetofrequirementsthat Whilewehaveexamineddozensofeortsaimedatdevelopingmeta-environments,itshouldbe environmentshaveemergedasakeystrategyforreducingthecost,time,andeortofconstructing meta-environmentstolearnagreatdealmoreabouttherequirementsforenvironmentsthemselves. softwareproductionenvironments.iftheserequirementscanbemet,researcherswillbeabletouse Furthermore,meta-environmentswillenabletheproductionofanewgenerationoflarge-scale outlineaboldagendaforresearchanddevelopmentintheareaofmeta-environments.metaspecicenvironmentsandapplicationsthatcanmostreadilybeproducedandsupported. meta-environments.thus,theultimatepayofrommeta-environmentswilllieinthedomain- softwareapplicationsthatareengineeredusingdomain-specicenvironmentsconstructedfrom Corporation,theUSCCenterforOperationsManagement,EducationandResearch(COMER),and others.noendorsementimplied. grantstotheuscsystemfactoryprojectfromattbelllaboratories,hewlett-packard,northrop Acknowledgements:Preparationofthisreportwassupportedinpartthroughcontractsand 19

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