Table Of Content·
Nathan Griffiths Kuo-Ming Chao
Editors
Agent-Based
Service-Oriented Computing
123
Editors
Dr.NathanGriffiths Prof.Kuo-MingChao
UniversityofWarwick CoventryUniversity
Coventry Coventry
UK UK
ISBN978-1-84996-040-3 e-ISBN978-1-84996-041-0
DOI10.1007/978-1-84996-041-0
SpringerLondonDordrechtHeidelbergNewYork
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Contents
1 Introduction................................................ 1
Kuo-MingChaoandNathanGriffiths
1.1 DistributedSystems ....................................... 1
1.2 SoftwareAgents .......................................... 2
1.3 Service-OrientedArchitectures.............................. 4
1.4 ModellingMethodologies .................................. 5
1.4.1 AgentModellingMethodologies..................... 6
1.4.2 SOAModellingMethodologies...................... 7
1.4.3 AgentsandServices ............................... 8
1.5 SupportingDevelopmentPlatforms .......................... 9
1.6 AgentsandSOAStandards ................................. 10
1.6.1 FoundationforIntelligentPhysicalAgents(FIPA) ...... 11
1.6.2 SOAandWebServiceArchitectureStandards.......... 11
1.7 OverviewofChapters...................................... 13
1.8 Conclusion............................................... 17
References..................................................... 17
2 ServiceAdvertisementandDiscovery........................... 21
ShanshanYangandMikeJoy
2.1 IntroductiontoServiceAdvertisementandDiscovery ........... 21
2.2 BasicTechnologies........................................ 24
2.2.1 SOAP ........................................... 24
2.2.2 WSDL........................................... 25
2.2.3 UDDI ........................................... 25
2.3 WebServiceRegistryArchitectures .......................... 26
2.3.1 CentralisedRegistries.............................. 26
2.3.2 DecentralisedRegistries............................ 27
2.3.3 HybridRegistries.................................. 30
2.4 DataStructures ........................................... 31
2.5 SystemRequirements...................................... 33
2.6 AdvertisementandDiscoveryServices ....................... 34
2.7 AgentsinServiceAdvertisementandDiscovery ............... 36
2.7.1 AgentsinServiceOrientedComputing ............... 36
2.7.2 Development of Agents in Service Advertisement
andDiscovery .................................... 37
2.8 ChallengesinServiceAdvertisementandDiscovery ............ 40
2.8.1 SystemRequirements .............................. 41
2.8.2 SystemModelling ................................. 41
2.9 Summary ................................................ 41
References..................................................... 42
3 Multi-AgentCoordinationforServiceComposition............... 47
JunzhouLuo,WeiLi,BoLiu,XiaoZhengandFangDong
3.1 Introduction.............................................. 48
3.2 Preliminaries ............................................. 49
3.2.1 ServiceComposition............................... 49
3.2.2 QoSAttributesandUserSatisfactionDegreeofService . 52
3.2.3 TaskGraph....................................... 53
3.2.4 ServiceCompositionGraph......................... 54
3.2.5 FromTaskGraphtoServicesCompositionGraph ...... 55
3.2.6 TheFundamentalsoftheAntAlgorithm .............. 56
3.3 RelatedWork............................................. 57
3.3.1 FrameworkofServiceComposition .................. 57
3.3.2 ServiceCompositionPlanGeneration ................ 58
3.3.3 ServiceSelectionandPlanOptimization .............. 58
3.3.4 Multi-AgentBasedServiceComposition.............. 59
3.4 ArchitectureofMQSC..................................... 60
3.4.1 PortalAgent...................................... 60
3.4.2 DecisionAgent ................................... 61
3.4.3 SearchAgent ..................................... 61
3.4.4 RegistryAgent.................................... 62
3.4.5 ManagementAgent................................ 62
3.4.6 ExecutionAgent .................................. 62
3.5 ServiceCompositionGeneration ............................ 63
3.5.1 ServiceSearchandCompositionPlanGeneration....... 63
3.5.2 QoS-AwareServiceSelection ....................... 64
3.6 ServiceCompositionDeploymentandExecution............... 66
3.6.1 HowtoManagetheEAtoImplementtheComposite
PlanfortheMA................................... 67
3.6.2 ThePlanSchedulingAlgorithmoftheEA............. 67
3.6.3 AnExamplefortheSchedulingAlgorithmoftheEA.... 69
3.7 CaseStudy............................................... 71
3.7.1 CaseScenarioDescription .......................... 71
3.7.2 Multi-AgentSystemforServiceComposition.......... 74
3.7.3 TravelAssistantServiceCompositing ................ 75
3.8 ConclusionandFutureWork................................ 78
References..................................................... 79
4 FlexibleWorkflowManagementinServiceOrientedEnvironments . 81
BirgitHofreiterandChristianHuemer
4.1 Introduction.............................................. 81
4.2 OrchestrationandChoreography ............................ 83
4.2.1 MotivationandDefinitions.......................... 83
4.2.2 Orchestration ..................................... 84
4.2.3 LocalChoreography ............................... 86
4.2.4 GlobalChoreography .............................. 88
4.2.5 Approaches to Transform Between Orchestration
andChoreography................................. 89
4.3 WorkflowandWebServices ................................ 90
4.3.1 WebServicesStandardsforBusinessProcesses ........ 90
4.3.2 SpecifyingaBusinessProcessbyMeansofBPEL ...... 90
4.3.3 AnalyzingBPELbyWorkflowPatterns ............... 97
4.4 TheRoleofAgentsinService-BasedBusinessProcesses........ 98
4.5 DynamicWorkflows.......................................100
4.5.1 DynamicSelectionofBestServiceProviders ..........100
4.5.2 ChangestotheWorkflowSchema....................103
4.6 SummaryandOutlook .....................................107
References.....................................................108
5 SemanticsforService-OrientedArchitectures.................... 113
MichaelStollbergandDieterFensel
5.1 Introduction..............................................113
5.2 WebServicesandSOA ....................................115
5.2.1 WebServices .....................................115
5.2.2 Service-OrientedArchitectures ......................117
5.3 SemanticWebServices ....................................119
5.3.1 OntologiesandtheSemanticWeb....................120
5.3.2 SWSFrameworks .................................122
5.4 SemanticTechniquesforAutomatingSOA....................126
5.4.1 Discovery........................................127
5.4.2 SelectionandRanking .............................129
5.4.3 BehavioralCompatibility ...........................130
5.4.4 Composition......................................130
5.4.5 Mediation........................................131
5.4.6 AutomatedExecution ..............................132
5.5 ConclusionsandOutlook...................................132
5.5.1 Summary ........................................133
5.5.2 FutureChallenges .................................134
References.....................................................135
6 DependabilityinService-OrientedComputing ................... 141
ArshadJhumka
6.1 Introduction..............................................141
6.2 Service-OrientedArchitecture...............................143
6.2.1 DependabilityIssuesinService-OrientedArchitectures..146
6.3 Models..................................................147
6.3.1 SystemModels ...................................147
6.3.2 FaultModels .....................................148
6.4 DependabilityEnhancementinaServiceOrientedArchitecture...152
6.4.1 FaultPrevention...................................152
6.4.2 FaultTolerance ...................................153
6.4.3 FaultRemoval ....................................154
6.4.4 FaultForecasting:FaultInjection ....................154
6.5 DependabilityEvaluation...................................155
6.6 CaseStudies .............................................157
6.6.1 AWeb-BasedApplication ..........................157
6.6.2 Service-OrientedComputinginUbiquitousSystems ....159
6.7 Conclusions..............................................159
References.....................................................160
7 ConsensusIssuesforServiceAdvertisementandSelection ......... 161
PingWang,Chi-ChunLoandLeonSmalov
7.1 Introduction..............................................161
7.1.1 SemanticConfusion ...............................162
7.1.2 ReachingConsensus ...............................164
7.2 ExistingSolutionsforWebServiceSelection ..................165
7.3 TheProposedQoS-AwareServicesSelectionModel ............170
7.3.1 BasicDefinitionsandNotations .....................171
7.3.2 ConsistenceandInconsistenceMeasurements..........171
7.3.3 ProblemFormulation ..............................174
7.4 TwoNumericalCases......................................176
7.4.1 NumericalCaseI..................................176
7.4.2 NumericalCaseII .................................179
7.5 Discussion ...............................................184
7.6 Conclusion...............................................185
References.....................................................185
8 TrustandReputation ........................................ 189
SarahN.LimChoiKeungandNathanGriffiths
8.1 Introduction..............................................189
8.2 TrustandReputation ......................................190
8.2.1 Trust ............................................190
8.2.2 Reputation .......................................191
8.2.3 TheMultipleApproachestoTrustandReputationModels191
8.2.4 ReviewofTrustandReputationModels...............194
8.2.5 SummaryofViewsofTrustandReputationModels.....210
8.3 AgentsandService-OrientedComputing......................211
8.3.1 Peer-to-PeerArchitectures ..........................211
8.3.2 GridComputing...................................215
8.4 TrustClassesandOntologies................................218
8.4.1 TrustSemantics...................................219
8.5 Summary ................................................220
References.....................................................220
9 QoS-AwareServiceSelection ................................. 225
JamesW.J.XueandStephenA.Jarvis
9.1 Introduction..............................................225
9.2 ServiceSelectionProcedure ................................226
9.3 CaseStudy—SelectionofSwitchingService ..................227
9.3.1 ServerSwitchinginInternetHostingCentres ..........227
9.3.2 ServerSwitchingProcedure.........................229
9.3.3 ModellingMulti-tierInternetServices ................229
9.3.4 ModelParameterisation ............................232
9.3.5 BottleneckIdentificationofMulti-tierArchitecture .....232
9.3.6 ServerSwitchingforRevenueMaximisation...........234
9.3.7 SwitchingPolicies.................................236
9.3.8 ProactiveandReactiveSwitching ....................239
9.3.9 AdmissionControl ................................240
9.4 PerformanceEvaluation....................................240
9.4.1 ExperimentalSetup................................240
9.4.2 EvaluationResults.................................241
9.5 TheSelectionofSwitchingServices .........................249
9.6 Summary ................................................250
References.....................................................250
10 FutureDirections ........................................... 253
NathanGriffiths,Kuo-MingChao,SimonMiles,SanjayModgil,Nir
Oren,MichaelLuckandKwei-JayLin
10.1 Introduction..............................................254
10.2 TrustandReputation ......................................254
10.2.1 Standardisation ...................................255
10.2.2 TechnologyIntegration.............................256
10.2.3 FurtherChallengesforTrustandReputation ...........257
10.3 Contract-BasedSystems ...................................258
10.3.1 ElectronicContracts ...............................259
10.3.2 ConceptualFrameworksforContract-BasedSystems....260
10.3.3 SupportingArchitecturesforContract-BasedSystems...260
10.3.4 ExistingWorkandFutureDirections .................261
10.4 ServiceAccountability.....................................262
10.4.1 IntroductiontoAccountability.......................263
10.4.2 SOAAccountability ...............................263
10.4.3 AccountableServiceComputingModel...............264
10.4.4 AccountabilitySystemComponents ..................267
10.4.5 RelatedWork.....................................268
10.4.6 FutureDirection ..................................269
References.....................................................270
Index .............................................................273
Chapter 1
Introduction
Kuo-MingChaoandNathanGriffiths
Abstract The increasing number and growing complexity of distributed systems
in current dynamic business environments requires more sophisticated methods
and technologies to tackle the related emergingissues and requirements. Software
agents,anAI-basedtechnology,hasdemonstrateditspotentialindealingwithun-
coordinatedheterogeneousdistributedsystems.Service-orientedcomputing,which
has evolved and learned lessons from Internet and distributed object technologies,
hasattractedsignificantinterestfromindustryandacademiaforthedevelopmentof
distributedenterprisesystems.Thischaptergivesanoverviewofthecharacteristics
ofagentsandservicesandtherelationshipsbetweenthembyanalysingtheirmod-
elling methods, supporting specifications, and platforms for system development.
We argue that although the focus of these two technologies is diverse, they have
greatpotentialtocomplementeachothertoadvancedistributedapplications.Inthis
chapterwealsointroducetheremainingchaptersofthisbook.
1.1 DistributedSystems
TheincreasingpopularityoftheInternetfacilitatessoftwareaccessibilityandinter-
action. Due to rapid changes in the operating environment and increased demand
for sophisticated functionality from software, centralised approaches for the man-
agementanddevelopmentoflargescalesoftwarebecomesalessviableoption.The
growingnumberofdistributedsystemswithassociatedsupportingtechnologies,and
thetrendtowardsglobalisation,hasshapedthenewlandscapeofcomputersystem
Kuo-MingChao
DepartmentofComputerScience,CoventryUniversity,Coventry,CV15FB,UK
e-mail:[email protected]
NathanGriffiths
DepartmentofComputerScience,UniversityofWarwick,Coventry,CV47AL,UK
e-mail:[email protected]
N.Griffiths,K.-M.Chao(eds.),Agent-BasedService-OrientedComputing, 1
AdvancedInformationandKnowledgeProcessing,
DOI10.1007/978-1-84996-041-0 1,(cid:13)c Springer-VerlagLondonLimited2010
2 Kuo-MingChaoandNathanGriffiths
development,whichputsmoreemphasisonissuessuchasflexibility,interoperabil-
ity,reusabilityandQualityofService(QoS).
Software agents are one of a number of fast growing technologies designed to
cope with increasingly dynamic and complex environments. Its theory has been
widely studied and the breadth of its applications range from engineering to busi-
ness; from personal assistants to large-scale system integration. The emergence of
service-oriented computing has provided an alternative way to design and model
softwaresystemsandthishasgainedalargedegreeofsupportfromacademiaand
industryalike.Asaresult,anincreasingnumberofcompaniesareadoptingservice-
oriented architectures (SOAs), and the related technologies, to implement their IT
systems.
Althoughagent-orientedandservice-orientedcomputinghavedifferentperspec-
tivesfromwhichtheycontributetodistributedsystemdesign,theyshareanumber
of common characteristics in software development, such as raising system scal-
ability, emphasising system abstraction modelling, increasing software reusability
anddistributedsystemscoordinationetc.Softwarecomponentscanbeorchestrated,
composed or coordinated to produce a compelling distributed system that none of
theindividualcomponentscanaccomplishalone.This,however,raisesthequestion
of whether, given that they overlap, these paradigms can work together with suf-
ficient effectiveness to further improve distributed system design. If the answer is
yes, then a further question is determining how they can complement each other.
Inthischapter,weexaminethesetwotechnologiesbylookingintovariousaspects.
We will give more background on agent-oriented and service-oriented computing.
WealsobrieflyintroducethedefinitionsandpropertiesofagentsandSOAs,asthese
mayleadtothevariousmodellingmethodologiesandthefocusoftheirapplications.
Finally,weincludeabriefoverviewoftheremainingchaptersofthisbook.
1.2 SoftwareAgents
Thetermagenthasbeenextensivelyusedincomputerscienceandthereisnogen-
eral consensus on its definition. W3C defines an agent as, “a program acting on
behalf of a person or organisation” [15]. This definition gives space for develop-
ers to give varying interpretations to the definition in shaping their agents. This is
understandableasW3CinvolvesseveralinitiativesinstandardisingInternet-related
specifications.Ifthedefinitionistoodetailedandspecific,itmayhinderthescopeof
applicationsanddevelopment.Accordingtothisdefinition,someagentscanpossess
sophisticated and complex functions, while others can be very simple which only
containaprogramroutine.Berners-Leeetal.[2]view,forexample,softwareagents
in the context of semantic web technologies as being responsible for coordinating
searchesandcomparingandnegotiatingonthewebtogreatlyreduceauser’seffort.
Bradshaw[3]concludedthatthe“softwareagent”definitionproposedbyShoham
in1997mightbeacceptabletomanyagentresearchers.Thatis,“asoftwareentity
whichfunctionscontinuouslyandautonomouslyinaparticularenvironment,often
