GasMASkAnnotation-basedCodeGenerator asanEmbeddedDomain-SpecificLanguagein
CollaborativeMulti-AgentSystems
Or¸cunOru¸c,UweAßmann
TUDresden,SoftwareTechnologyGroup,N¨othnitzerStraße46,01187, Dresden
Abstract. Multi-agentsystemshaveevolvedwiththeirapplicationframework,analysisapproaches anddesigncomplexitiesoverthepastfewdecades.Inorderforprogrammingsoftwareagents,you needtohandleanalysis,designandimplementationtogether;furthermore,privacyandtrustshould beintegratedexternallyintotheagent-orientedapplications.Currentframeworksdonotconsider privacy,trust,anddataintegrityinagentapplications.
Inthisstudy,weproposeadomain-specificlanguagethatcanbeusedforagentbehaviorsthat consistofroles,organizationalentity,goalsthroughannotationprocessingwithtemplates.Smart contractscanbegeneratedtodecreasethetimefordeploymentanddevelopmentstages.Templates andannotationsarepopulartechniquestoreduceboilerplatecodebasesfromagent-orientedprogramming.Thesetechniquescanalsobeusedformodel-drivensoftwareengineering.Thisstudy willtakethesoftwareagentdevelopmentasawholewithanalysis,design,anddevelopmentwith embeddeddomain-specificlanguagedevelopmentintermsofsmartcontractapplications.Furthermore,wewouldliketorefertomethodology,resultsoftheresearch,andcasestudytoenlighten readersinabetterway.Finally,wesummarizefindingsandhighlightthemainresearchpointsby inferencingintheconclusionsection.
Keywords: Softwareagents,Domain-specificlanguages,Blockchaintechnology,Smartcontracts, Role-basedprogramminglanguages,CodeGeneration,Template-basedcodegeneration
1Introduction
Agent-orientedprogramming(AOP)canbeconsideredasasubjectofobjectorientedprogrammingbyshowingthestateofanobjectwithhuman-likefeatures suchasbelief,desire,intentions,andgoals.Moreover,anagentshouldbeintheinteractionwithotheragents,inthisway,agentsareabletoplayrolesashuman-being does.AOPspecializestheobject-orientedprogrammingmethodologybyfixingstate andmodules,whicharecalledagents,toconsistoffeaturesthatcomefromagent behaviors.Besides,anagentcanhandlethemessagepassingbetweenotheragents internally.
Agent-basedsystemshavechangedtheircharacteristicsoverthepastfewdecades aspectofdesign,analysis,andimplementation.Althoughonecanfindoutthedif-
ficultyofexactdefinitionintermsofthemulti-agentsystem,multi-agentsystems areusedbroadlyintheapplicationareassuchassupplychainmanagement,distributedsystems,smartgrids,roboticmotionplanning.Multi-agentsystemsare stronglydependentoncontextsandroles.Eachagentplaysaroleandithasa minimalsetofattributesthatrepresentstheenvironment.Moreover,agentsshould havebehaviorsthatare,inessence,relatedtoimplementingdeterministicornondeterministicbehaviorsofanagentthatoperatearolethatcanbeinsequential order,cyclicorder,orparallelorder.
Softwareagentshavesomemandatoryfeaturesinordertocompletetasksthat havebeengivenbydevelopers.Agentmustperceptthesurroundingenvironment throughinformationreceivedfromtheenvironmentbysensors.Andthenanevent shouldbecreatedbyanagenttocreateknowledgeabouttheenvironment.This hasbeencalledbeliefs,whichprovidessomeaspectoftheagent’sknowledgeabout theenvironment[1].Afterdefiningaconcretegoalforanagent,eventsareoften extractedfromperceptsandtriggeredbyanewaction[2].
Agentsmustbeinarelationshipwithexternaltrustedpartiestoprovideprivacy andconsistencyinmulti-agentsystems.However,thetrustwasmostlyprovidedby differentlogicinterpretationsandcumbersomeontologicaldefinitionsinmulti-agent systems.Blockchaintechnologyoffersacredibleandprivatedatapoolthatcanbe usedwithprogrammablecontracts(smartcontracts)asashareddatabase.Aswe solvedthecredibilityproblemwithblockchaintechnology,wecanenforcethedata layersecurity,whichisvitalfordata-drivenmulti-agentsystemcommunication,by implementingsmartcontractsontheapplicationlayeroftheblockchainprotocol.
Asmartcontractisapieceofcodethatisstoredonablockchainbytriggeringcoinbasedtransactionswithsaveddataandwhichreadsandwritesdatainablockchain database 1 .Inaddition,smartcontractscanensurethetestabilityofrolefeatures, securetransactionswithintheblockchaindatabase,andseparationofthebusiness logic(model)andapplicationlogic(systemarchitecture).
Theresearchpaperisstructuredasfollows.First,wewilldiscusstheimportance andshorthistoryregardingthetopicintheBackground2.IntheMethodology andContributions1.1chapter,wewillexplaincontributionsthatcanoccurat theendofthisresearchandemphasizeourobjectives,problemstatement,and researchquestions.Secondly,wewilllistsomelimitations1.2,whichwemight encounterduringthisresearch.Inthechapter3,weintroducepreviousstudies andsurveysthathavebeenconductedbefore.Later,wewillgivethedetailsof theimplementationinthechapter4.InthechaptercalledCaseStudy5,wewill introduceasampleconcept,whichwewouldliketoimplementwithourlanguage. Inchapter6and7,wewilllistourfindingsandtasksthatshouldbetakeninto considerationforfurtherresearch.
1 https://www.coindesk.com/three-smart-contract-misconceptions
1.1MethodologyandContributions
Firstofall,wehavetworesearchquestions.Toconcludeupregardingtheresearch problem,wehavedefinedresearchquestions(RQ)asbelow:
RQ1:Canadomain-specificlanguagethatcomprisesthemainfeaturesofagent communicationlanguage,agentframework,andsmartcontractlanguagebe created?
RQ2:Cantemplatesbeintegratedintoannotationprocessorsintermsofroles, goals,andcompartmentsinthedomain-specificlanguage?
Goal:
Themaingoalofthisresearchistoimplementadomain-specificlanguageto demonstratetemplatesamplesandcodegenerationforsmartcontracts.
Objectives:
– Implementingtemplatestocreateanddeleteagentsinoneoftheselectedframeworks.
– Definingannotationsforstatefulsmartcontractlanguageinorderfortheprocessofcodegeneration.
– Attheimplementationphase,wewilldefinesomeeventsinsmartcontractsto logtotheblockchainnetworksandspecifyagents’basicfeaturestobealivein anagentmanagementsystem.
Expectedcontributionswillbeinthefollowingitems:
Wewillhaveanewembeddeddomain-specificlanguagethattakesasawhole privacy,security,dataintegrityandrole-orientationinmulti-agentsystems.
– Wewillcreateatoolforstatefulcontractdevelopmentintheblockchaindatabase.
– Wewillhaveagenttemplatestoreduceboilerplatecodebaseandincreasethe learningcurveforagent-orientedapplicationsinapracticalframework.
1.2Limitations
Inthissection,wewilllistourlimitationsregardingtheprocessofwritingthe thesis.
– Wewillpresentcodetemplatesforagent-orientedsoftwareengineeringanddiscusswiththemetaprogrammingthroughannotationprocessing.
– Wewillfocusontheexistingmeta-modelsuchasCROMforspecifyingcommunicativeentitytypes.InthecontextofCROMresearch,wewillfollowthe guidelineregardingrolesandcompartmentsthathavebeenspecifiedbefore.
– Wewilldevelopanapplicationbasedonastatefulsmartcontractlanguage suchasSoliditythefollowingdesign-by-contractapproachthatinteractswith differentagentsinthecontextofrole-orientedprogramming.
ThisresearchislimitedtotheKQMLandFIPAagentcommunicationlanguages anditdoesnotcomprisestatelessblockchainlanguage.Duetothenatureofthe statelessblockchainlanguage,itdoesnotpurelysuitablefortheobject-oriented approach.
Asforontologicalrepresentation,semanticheterogeneitybetweenagent-oriented frameworkswillnotbetakenintoconsideration.Sowebasicallywillhandleexistingontologiesandwillnotadvancetoontologyengineering.
2Background
Codegenerationallowsyoutoproduceprogramcodethatisonlystronglytyped, andyetcanbeeasilyreconfiguredcodebasewhenthesourcemodelischanged
2 .Principally,codegeneratorsaremetaprogramstranslatingaregulartreetoa sentenceofacontext-freelanguage[3].Whenthecodegeneratortranslatesthe abstractsyntaxtreeintoacontext-freelanguage,itusesamodel,whichisthe definitionlanguageoftheagent,andview(result)inorderforrealizingtheoperation.Anabstractsyntaxtreeisatreerepresentationofthesyntacticstructure thathasbeenrepresentedinaprogramminglanguage.Inthisstudy,wewillwritea code-generatorinanad-hocfashion,whichisgoingtobewrittenforagent-oriented softwareapplications.Thecodegenerationprocessisaprojectionoftheinputdata modelintotooutputcodebase.Bydefininglanguagevocabularyinourembeddeddomainmodelinglanguage,wecaneasilygenerateanagent-orientedcodebasefor variouspracticalframeworks.
2.1Agent-OrientedProgramming
Anagentisanythingthatcanbeviewedasperceivingitsenvironmentthrough inputandoutputappliancesandactinguponthatenvironment
[4].Tounderstandanenvironment,agentneedstoregisterthestateofhistoryregardingtheenvironment.Agentshavebeendesignedtobetterunderstandthecomplexityofsoftwaresystems.Agent-to-AgentandAgent-to-Environmentinteractions areanimportantpartofagent-orientedprogrammingbecausethestateofpassive objectsissupposedtohaveinteractedinadynamicenvironment.
Themodelofgoals,roles,andorganizationsshouldbedesignedatthesystem level.Inthepracticalframeworks,thiscanbedonebymetamodelsormetaprogrammingwithanembeddeddomain-specificlanguage.Bothofthemethodscan generateagent-orientedcodewithsmartcontracts,butchangesshouldbeintegratedintothemetamodels.Modelandviewshouldbestrictlyseparatedinboth approachesandthemetamodelapproachtakesmoretimeforasteeplearningcurve.
Organizationalparticipantsareoneofthemostimportantfeaturesintheagentorientedworld.Forinstance,thecardealership,thebank,theschool,andtheinsurancecompanyareallexamplesoforganizationalparticipants[5].Agentorientation aimsatpursuingasoftwareparadigm.Themainresearchpointisaboutwhether theagent-orientedcanensureahigherqualitythanitspredecessorintermsof autonomy,reactivity,proactivity,andcooperativefeaturesinaparticulardomain.
Inpractice,roles,organizations,andgoalsaredefinedbymessagesthatcontain envelope,payload,message,andcontent[?].Agentplatformsarephysicalplatforms inwhichagentsaredeployedandorganized.Agentplatformsneedtoregisterto directoryfacilitatorinordertofindotheragentservicesinthenetwork[?].An agentcanmodifyitsagentdescriptionbysendingrequeststothedirectoryfacilitator.Agentsaredeletedorcreatedbyagentmanagementsystems,whichareone ofthecorecomponentsinpracticalagentframeworks.Lastly,organizationaland role-basedentitiesaredescribedinmessagesincompliancewithFIPAandKQML throughagentmessagingtransportservices.
2.2Role-orientedProgramming
Inanobject-orientedapplication,objectsareinarelationshipbetweenotherobjects andtheyaresharingtheirfeaturesofrelationshipsthroughconstraints,dependency, andinvariants.Eventhoughthereisnocommonunderstandingaboutrolesina programminglanguage,role-orientedprogrammingbasicallylooksforananswerto whetherornotanobjectcancollaboratewithdefinedrolesamongotherobjectsin theapplicationlifetime.
Rolesencapsulatethedynamicbehaviorofplayers,whicharethecoreobjects inthecontext,anddynamicallyadapttheplayers’behavior[6].Compartments arecontainerthatholdsmultiplerolesortheircollaborationfeatures.Rolescan makethedesignofmulti-agentsystemseasierbyimplementingthecompositionof roleattributes,roleinvariants,rolemethods,andbindinginterfaces.Thedifference betweenrolesandobjectsiswhetherornottherolescanmovehoststhatexistin theenvironment[7].Role-basedsoftwareagentsarerelatedtocontext-awaremultiagentsystems.Contextisanyinformationthatisaccessibletotheprogram,where anentityisaperson,place,oranotheragentthatisconsideredrelevanttothe determinationofbehavioralvariations[8].Agentscandynamicallycollaboratewith roles,createcoalitionsoftrustedpartnersasaneffectivemechanismtocommunicate withservicerequestors,findservicesrequestedbythem,anddeterminetrusted servicesandprovideservicestotheapplicantswithoutviolatingtheprivacyofthe predefinedenvironment[9]
CompartmentsbelongtotheresearchoftheCompartmentRoleObjectModel (CROM)thatestablishessubtypesofnaturaltypesandrelationshiptypesamong combinedroles[10]
2.3SmartContracts
Smartcontractsareapieceofcodethatcanbetriggeredbyblockchainnetwork throughtransactions.Morespecifically,asmartcontractisasecureandunstoppablecomputerrepresentinganagreementthatisautomaticallyexecutableand enforceable[11].Atransactionisasigneddatapackagetotransfervalue,which canbecoinbasevalue,fromanaccounttoanotheraccountortoacontract,invoke amethodofacontract,ordeployanewcontract[11].Principally,anorganization hasanidentityanditsownpurpose[11].
Smartcontractsaredeterministicapplications,whichmeansthattheapplicationsproducethesameoutputseverytimetheyarecarriedout.Theyalsohave somepreconditionsandpostconditionsthatfocusontheconditionlogicofapplicationsratherthansyntaxoralgorithmsinpractice.
Blockchainnetworksbehaveinadistributedanddecentralizedmanner,which providesimmutable,permissionlessorpermissionedsolutionsinaprivateorpublic environment.Consensusisthebackbonemechanismofablockchainsolutionthat iscomprisingofvarioustypesofthemsuchasproof-of-work,proof-of-stake,proofof-authority.Theselectionoftypesofconsensusshouldbedefinedbyblockchain technology,sothetechnologychoiceisoneoftheimportantparametersforsmart contractapplications.Forinstance,CordaapplicationsdonotprovidecertaindeterminismjustliketheEthereumtechnologybecausedevelopershavedesignedthe Cordablockchainnetworkasadistributedledgerwithoutdesigningaparticular virtualmachineenvironment.Inordertoensuredeterministicbehaviorsinthe blockchainnetworks,theymustimplyhonestagreement,propertermination,the validityofnodes,andfault-tolerant.
Onecantransfervaluewithafixedordynamicpriceintheblockchainnetwork,whichiscalledon-chaintransactions.Fordeterministicvaluetransfer,onchaintransactionsmustbeexecutedintheblockchainvirtualmachine.Statefulor statefultransactionscanbemadeineitherdeclarativeprogramminglanguagesor imperativeprogramminglanguages.Agentswhowanttojointhenetworkshould takepermissionfromthenetworkadministrator.Hence,wecanrestricttheaccess foranyexternalparticipantswhowanttoconnectwiththeinternalblockchain networkthatiscalledpermissionedblockchain.Thisprovideshighthroughputand lowlatencyintheblockchainnetwork.However,thenatureofblockchainisalways permissionlessbecauseallnodescanparticipateinthenetworktosynchronizetheir internalblockdatastructures.
DynamicSmartContracts
Asmartcontractcanexecuteasset-valuetransfersintheblockchainnetworkor executeanexternalcontractbypassingitsaddress.Thus,asmartcontractcan
Forpermissionlessandpermissionedblockchain, onceasmartcontractisdeployed,thesmartcontractremainsimmutable[12].
triggeranothersmartcontractoritselfwithdifferentattributes.Thisisthepoint thatwecancreatedynamicsmartcontracts.
Dynamicsmartcontractsdealwiththemaintainabilityofimmutablesmart contractsinordertochangetheirbehaviorsatruntime.Reconfigurationofasmart contractthatiscalledbymultiplecontractsmighthaveseeneffectivetoimplement; however,deploymentoverloadcanaffecttheperformanceoftheblockchainnetwork. Dynamicsmartcontractsarenotimplementedinthisstudy;nevertheless,wewill considerthebehaviorchangesusingparameterpassingfromexternalcontractsto realizepartlydynamicstatesforagentsintheblockchainnetwork.
2.4Domain-SpecificLanguagesforMetaprogramming
Domain-SpecificLanguages(DSLs)haveasmallsetoffeaturesandtheyaremostly optimizedforaspecificdomainsuchashealth,finance,ormanufacturing.Byoptimizingforaspecificdomain,aDSLcanbeeasilymaintainedandbuiltupona general-purposelanguagewithoutdefiningdeeplytheunderlyingconceptoflanguagedesign.Inthisstudy,wehavechosenageneral-purposelanguagecalledJava, whichprovidesPluggableAnnotationProcessingAPIthatdealswithadvanced customizedannotationsatcompileorruntimelevels.Inthisstudy,webasically generateanembeddeddomain-specificlanguagethatgeneratesapieceofcodeina general-purposelanguageandastatefulsmartcontractlanguage.Atthefirststage oftheresearch,applicationswillbegeneratedbytheembeddeddomain-specific language.Later,wewillfocusonthefeatureoflanguagewhetherornotitchanges thebehaviorofexistingprograms.
3StateoftheArt
ALAADINisoneoftheoldestmetamodels[13]todefinemodelsoforganizationsfor agentsandthismodeldefinesaverysimpledescriptionofcoordinationandnegation schema[13].Theauthorsdeterminethattheroleisanabstractrepresentationofan agentorservicefunctionwithinagroup.Groupsareasetoffeaturesthatbehave asanatomicentitysothatanagentdynamicallyjoins,creates,orleavesgroups [14].
Whenwefocusonbehavioralrolesforagentinteraction,(Cabriet.al.2003) proposedthatanagentsystemdefinesaroleasasetofcapabilitiesandexpectedbehaviors.BRAINisanapproachthatcoversarole-basedinteractionmodel, whereagents’interactionsandbehaviorsareembeddedinroles[14].Moreover,they achievedandadvisetorealizeagent-orientedfeatures,separationofconcerns,and reuseofsolutions[15].Todescribeagentssemantically,theydefinedalanguage calledXRolethatexploitsbuilt-updefinitionsofroles.Thesedefinitionsconsistof name,description,addresses,roledescription,andcontentsoftheagentswithrelationalfeaturessuchas MinOccurs and MaxOccurs
infrastructurethatimplementsthemodelofBRAIN[16].RolesdefinedbyXRole canbereadbyhumansaswellasbyagentsandtools[16].TheRoleSystemprovides twomaincomponentswhichare: reqRegistration,toregisteranagentinthesystem withaspecifiedrole; searchForRoleAgent,tosearchforagentsplayingagivenrole betweenagentsandserveragents[16].
Theplanningcapabilityofmulti-agentsystemsisoneofthekeyfeaturesthat theblockchainshouldtakecareofit.Afterassigningroles,planexecutionofthe multi-agentsystemsshouldcompletedistributedorderingactions.Todoso,asmart contractcanbeusedwhichareessentiallycollectionsofdistributedcodeanddata representingsomebusinesslogicthatworkswiththeblockchaindistributedconsensusprotocols[17].Themainideaofthispaperistocoordinatethestepsof multi-agentsthroughthesmartcontractsaspectofdistributedplanexecution.In thisplanexecution,multiplesmartcontractscanbeusedsuchasoraclecontract, whichisallowingtoexploitsdataintheoff-chainstorage,orcontractofpreconditionsandpostconditionstoprovidethedesign-by-contractpattern.
Gaiaisoneofthemethodologiesatthedesignandanalysisphasesinmulti-agent systems.Themaingoalofthismethodologyistomodelmulti-agentsystemsforan organizationwheredifferentrolesinteract[14].TheGaiamethodologydefinesthe featuresofrolesasbelow:
– Responsibilities:Theyspecifythefunctionalitiesofagentsthatplayroles.
– Permissions:Theyareasetofrightsassociatedwithrolesinwhichagentsplay.
– Activities:Internalcomputationofanagent.Thisdoesnottakeintoconsiderationtherelationshipbetweenagents.
Protocols:Thisisrelatedtointeractionrolesindicatingagent-to-agentcommunication.
Therole-basedevolutionaryprogramming(RoleEP)presentscooperativemobileagentstocollaborateinachievingacommongoal[14].TheauthorsofRoleEP statethatanobjectbecomesanagentbybindingitselftoarolethatisdefinedin adynamicenvironment[7].Theauthorshavedefinedthebasicconceptasbelow [7].
Environment: Anenvironmentiscomposedofenvironmentattributes,methods ofenvironment,androles.
Roles: Arole,whichcanmovebetweenhoststhatexistinanenvironment, containsroleattributes,rolemethods,andbindinginterfaces.
Objects: Anobject,whichcannotmovebetweenhosts,iscomposedofattributes andmethods.
– Agents: Anobjectthatbindsitselfwithsomerolesandacquirestraveling/collaborationfunctionsisnamedasAgents.
– BindingInterface: Abindinginterface,whichlookslikeanabstractmethod interface,isusedwhenanobjectbindsitselfwitharole.
Implementationofadomain-specificlanguagemayhavemetamodeldesign pathsatthelevelofM1(UserModel),M2(UnifiedModelingLanguage),M3(Meta ObjectFacility).Forinstance,AgentDSLisadomain-specificlanguageforcrosscuttingconcernsforagents,whichissupportingaspect-orientedprogramming,and non-crosscuttingconcerns[18].TheauthorsofAgentDSLdefinesacodegenerator thatmapsabstractions.
4Implementation
Principally,theselectionofthegeneral-purposelanguageisanimportantparameterregardingtheimplementationofcodegeneratorsbecausesomelanguagesgive native-insupportforcustomannotations.Forinstance,Javaprogramminglanguage supportsAnnotationProcessorwhichisequivalenttoaplug-inofthecompiler.
4.1AlgorithmoftheCodeGenerationwithMetaprogramming
RuntimeorCompile
roundEnvironment.getElementsAnnotatedWith(classname) scanforelements
AgentImplementautoImplement=element.getAnnotation(AgentGenerator.class);
13: endwhile
14: endprocedure
Theafore-mentionedalgorithmcanbeusedwithanygeneral-purposelanguageeven thoughithasbeenmentionedforJavalanguage.Moreorless,theannotationprocessfollowsstepsthathavealreadybeenexplainedtoreaders.Themostimportant pointabouteithertheRetentionPolicyshouldassignparticularconfigurationsat runtimeorgeneratecodebaseatthecompiletime.Thedevelopershoulddecidethe behaviorbeforeitwasdevelopedinagent-orientedframeworks.
4.2Template-basedCodeGeneration
ApacheVelocity3 isatemplateprojectthathasbeenprovidedbyApacheFoundation.Templatescantakeinputsinternallyorexternallythroughgeneral-purpose language.Oneofthedisadvantagesregardingtemplateshaslackofvalidationsteps atthecompiletime.Nevertheless,thisissuecanbesolvedbypostcompile-time validation.Generatedsourcecodecanbeintegratedwithcompilerplugininorder tocheckdatatypevalidation.Thefollowingcodesnippethasbeendemonstrated asbelow:
1 package ${packagename};
2 #set($classkeyword= " class " )
3 #set($classwithString= " class toString () " )
4 #set($dfDescription= " DFDescription " )
5 #set($agentID= " setName ( getAID () ) ; " )
6 #set($addServices= " . addServices ( serviceDescription ) ; " )
7
Aftercompilingtheprogramfromatemplate,avalidationstepmustbedone byanexternalapplicationprogrammableinterface(API).MostoftheprogramminglanguagesprovidetheCompilerAPIthatmightgeneratediagnosticsduring compilationsuchaserrormessages,warning-debug-infolevellogs 4 .Anembedded compilerpluginisabetterwaytodoit;however,externalcompilerAPIcantest theapplicationbetweenmultipleversionsanditprovidesplentyofbenefitstothe agentapplicationprogrammer.Inthefollowingcodesnippet,thecodebasehasbeen takenfromtheJThereumProject 5
Thefollowinglinesshowusageneratedcodebasefromastatefulsmartcontract language.
4.3Metaprogramming
Metaprogrammingistheabilitytowriteprogramsthatgeneratesourcecodedefinedbydevelopers[19].Beyondthatinsomeprogramminglanguagessuchas GroovyandRuby,onecanchangethebehaviorofexistingmethodsinorderfor realizingdynamicmetaprogramming.Forinstance,Javaofferstwotypesofstatic metaprogrammingsuchasannotationprocessingandaspect-orientedprogramming togeneratecodebase;however,dynamicmetaprogrammingcanbeachievedbyexternalthird-partylibraries.
Ameta-objectprotocol(MOP)representsthesemanticoftheextendibilitythat residesinaprogramminglanguage.Thebehavioroftheprogramisdeterminedby theMOP,includingtheaspectoftheprograminruntimeandcompile-time[19].
Everyaspectofaprogram’smappingdownontothelowerlevelsubstratethat iscontrolledbyobjectsincompileorruntime 6 .Theseobjectsarecalledmetaobjects,becausetheprimarydutyoftheseobjectsistomaptheprogram,notto representthepredefineddomain.Forinstance,thejava.lang.reflectpackageinJava, onecancreateaself-configuringsystemwithpluggableannotationsandtemplates.
Principally,metaprogrammingisdividedintotwomainparts,whichareruntime metaprogrammingandcompile-timemetaprogramming.Compile-timemetaprogrammingletsyouorganizegeneratedcodebaseatcompiletime.Youcanperform syntactictransformationsandcodeoptimizationleveltointeractwiththecompiler duringthecodegenerationphase[19].
5CaseStudy
Manufacturingschedulingistheprocessofassignmentoftimingfororder,manufacturing,anddelivery.Soweshouldprovideagoodqualityperunitandthenumber ofunitsshouldbemaximizedperslotintheproductionline.Atthesametime,we needtominimizethewasteofresourcerequirementsandpotentialfailures.Basically,thenextstateofsmartcontractsinablockchainenvironmentiscompletely determinedbythecurrentstate.
Wecancreateroletypes,naturaltypesandcompartmenttypesinorderforimplementingasamplecaseforGasMASklikeinthefollowingfigure1.Wewouldlike 6 https://wiki.c2.com/?MetaObjectProtocol
toimplementasupplychainmodelingbyrealizingdatastructuresinrole-oriented programminginsmartcontracts.Smartcontractswilltakethedatastructureand evaluatetheminobject-orientedprogrammingwithpreconditionsandpostconditionsastheunittestingframeworkdoes.
Aproducttypeiscreatedforamanufacturingsimulationtosimulatebetween retailer,wholesaler,andmanufacturingcompany.Whenwedefinedtypeofdata structuresforroles,theywillbecreatethroughannotationprocessingbydeploying inablockchainnetwork.Alloftheparticipantswillseeevents,transactionsand valuesintheblockchainnetworkandthetypeofblockchainnetworkwillbepermissionedblockchaintoprovidesecurityandtrust.RetailerProduct,WholeslarProduct,andFactoryProductaretheabstracttypesthatareimplementedfromProduct type.Thesetypeswillbeusedforagents’behavior.NaturaltypesinFigure1are goingtobeinSoliditylanguagesothatonecanusethemforverificationand immutablebehaviors.
Fig.1. Exampleoftheroletypes
6Conclusion
Thepaperaddressedthechallengeofcompellingtrustandsecurityinmulti-agent systemsandtheirrole-orientedfeaturesbyrealizingsmartcontractsregarding blockchaintechnology(BCT).Themainpurposeoftheresearchistogiveanew approachtotheintersectionbetweensmartcontractprogramming,role-oriented programming,andagent-orientedprogramming.Thecourseoffindingsamongvariousresearchareasguidesustodesignadomain-specificlanguagetocontributeto themulti-agentsystemarea.
– Thereisnocommonunderstandingintermsofmulti-agentsystemmethodology,analysis,design,orimplementation.Thisincreasesthecomplexityofthe researchinthemulti-agentsystemarea.
Thelimitednumberofdomain-drivenagent-orientedlanguageshavebeenprovidedsothatonecannoticethatmulti-agentsystemresearchismostlikely conceptualanditdoesnotprovideprototypeandresult-evaluatedresearch.
Synthesizedmetamodelingfromscratchindifferentresearchareascanbeambiguous;thus,webelievethatembeddeddomain-specificlanguagewithblockchain cansolvemostoftheproblemsformulti-agentsystems.
– Role-orientedprogrammingwithsmartcontractsischallengingbecausethe choicesoftechnologycanaffecttheresultofthestudy.Forinstance,statefulandstatelesscontractsarenotadvancedtechnologiesthatcanemployallof thefeaturesoftheobject-orientedparadigm.Turingcompleteandnon-Turing completetechnologieswillbescrutinizedinfuturework.Inanutshell,thispaperpresentedanewsignificantroleapproachwithsmartcontractprogramming implementinghashdatastructureandprovidingdatasecu-rityregardingroles. Presentingourapproachwillsimplifytheapplicationdevelop-mentprocessfor furtherresearchers.
Inparticular,thisstudyinspectsrole-orientedmulti-agentsystemsregarding domain-drivendesignandblockchaintechnologyinmulti-agentsystemsseparately. Thecourseoffindingcommonpointsbetweenvariousresearchareasguidesusto designadomain-specificlanguagetocontributetothemulti-agentsystemarea. Thereisnocommonunderstandingintermsofmulti-agentsystemmethodology, analysis,design,orimplementation.Thisincreasesthecomplexityoftheresearchin themulti-agentsystemarea.Thelimitednumberofdomain-drivenagent-oriented languageshavebeenprovidedsothatonecannoticethatmulti-agentsystemresearchismostlikelyconceptualanditdoesnotprovideprototypeandresultevaluatedresearch.Synthesizedmetamodelingfromscratchindifferentresearch areascanbeambiguous;thus,webelievethatembeddeddomain-specificlanguage withblockchaincansolvemostoftheproblemsformulti-agentsystems.Consequently,thispaperpresentedanewsignificantroleapproachwithsmartcontract
programmingtoencryptdataandtoprovidedatasecurityregardingroles.Introducingthisapproachwillsimplifytheapplicationdevelopmentprocesswithan embeddeddomainspecificlanguage.
7FutureWork
Infuturework,wewillfocusonthefollowingfeatures:
RuntimemetaprogrammingextendabilityoftheGasMASkcodegeneration.
Dynamicsmartcontractintegrationintotheembedded-domainspecificlanguage.
Wewillresearchontheruntimefeatureofcodegenerationwithastatically typedlanguage,whichmeansthatalanguagecandotypecheckingthetypeof variableatcompiletime.Mostofthedynamicallytypedlanguagecanhandlethis; however,mostoftheagentframeworksarewritteninastaticallytypedlanguage. Anotherconsiderationwouldberegardingroletypesandnaturaltypesatruntime adaptability.Separately,wewillconductresearchondynamicadaptabilityona deterministicblockchainenvironment.
Acknowledgements
Theauthorwouldliketothankhissupervisors,Prof.Dr.UweAßmann,andProf. Dr.SusanneStrahringer,forthepatientguidance,encouragement,andcomments theyhaveprovidedtoshapehisdoctoralvision.ThisworkisfundedbytheGerman Research(DFG)withintheResearchTrainingGroupRole-BasedSoftwareInfrastructuresforcontinuous-context-sensitiveSystems(GRK1907,TUDresden,SoftwareTechnologyGroup,N¨othnitzerStraße46,01187,Dresden).
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Author
Or¸cunOru¸c receivedM.Sc.fromTUChemnitz,andhegraduatedfromKocaeli UniversitywithaB.Sc.degree.Currently,heispursuinghisPh.D.inComputer Engineering-SoftwareTechnologyattheDresdenTechnicalUniversity.Hisresearch interestsincludeprogramminglanguages,multi-agentsystems,role-orientedprogramming,naturallanguageprocessing,decentralized,anddistributedapplications.