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WS-Agreement Tutorial Material. 2004/09/13 Toshiyuki Nakata NEC Corporation. Recent Status. Split the spec into two parts Basic Specification for agreement named Web Services Agreement Specification and Advanced Web Services Agreement Negotiation Specification (WS-AgreementNegotiation)
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WS-Agreement Tutorial Material 2004/09/13 Toshiyuki Nakata NEC Corporation
Recent Status • Split the spec into two parts • Basic Specification for agreement named Web Services Agreement Specification and Advanced Web Services Agreement Negotiation Specification (WS-AgreementNegotiation) • Graap-WG decided to put priority on discussing WS-Agreement first. • On 25th August WS-Agreement specification was submitted to the GGF editor, on track to enter public comment. • WS-Agreement itself is sort of a frame-work for getting agreements on several different domains. The details of things to be agreed are of course domain-specific and is out of the scope of the WS-Agreement Spec. • Eg. Job-submission using JSDL is a candidate to be used within the frame-work. • Relation to other specification • Relies on WS-Addressing • Also Relies on WS-ResourceProperties
Two layer Model • The service layer represents the application-specific layer of business service being provided. • The agreement layer provides a Web service-based interface that can be used to represent and monitor agreements with respect to provisioning of services implemented in the service layer. • An agreement port type, without any operation other than getters for state and metadata of the agreement such as the terms, the context, etc…. • An agreement factory exposes an operation for creating an agreement out of an input set of terms. It returns an EPR to an Agreement service. The agreement factory also exposes resource properties such as the templates of offers acceptable for creation of an agreement.
Agreement Initiator Agreement Provider Simple Sequnce-1 Query(wsag:template) (templates) Based on the Template create an offer CreateAgreement(offer) Decide to agree To the offer Create an agreement (EPR to Agreement1) Agreement1 At this moment the agreement is Observed. A-I cannot refuse to the Created Agreement
Agreement Initiator Agreement Provider Simple Sequnce-2 Query(wsag:template) (templates) Based on the Template create an offer CreateAgreement(offer) Decide to refuse (Return a Fault)
Agreement Name Context Terms Compositor Service Description Terms Guarantee Terms Organization of Agreement • Name: Optional Name • Context: Describes ‘meta-data’ of the whole Agreement • Parites to Agreement • Agreement Life-time • Template Name • Related Agreements • Agreementterms • Term Compositor Structure:A scheme to compose an AND/OR/XOR relationship of the following two elements • Service Description Term: Information needed to instantiate or identify a service to which this agreement pertains • Guarantee Term:Service Levels that the parties are agreeing to.
Agreement Context Terms Compositor Service Description Terms Guarantee Terms Agreement Context • /wsag:AgreementContext/AgreementInitiator • Agreement Initiator: (Requestor) • Can be an URI or wsa:EndpointReference(EPR) • /wsag:AgreementContext/AgreementProvider • Provider • Can be an URI or wsa:EndpointReference(EPR) • /wsag:AgreementContext/ExpirationTime • Specifies the time at which this agreement is no longer valid. • /wsag:AgreementContext/TemplateName • Specifies the name of the template from which this agreement is created. • /wsag:AgreementContext/RelatedAgreements • This element defines a list of related agreements: (Example??) <wsag:AgreementContext> <wsag:AgreementInitiator>xs:anyURI</wsag:AgreementInitiator> <wsag:AgreementProvider>xs:anyURI</wsag:AgreementProvider> <wsag:ExpirationTime>xs:DateTime</wsag:ExpirationTime> <wsag:TemplateName>xs:string</wsag:templateName> <wsag:RelatedAgreements>...</wsag:RelatedAgreements> </wsag:AgreementContext> PS what is /wsp:Context in page 15?
Example of usage of related Agreements: • Would really like to embed something like one shown below, but I am not confident whether this is valid or not..
Term Composite Structure <wsag:Terms> <wsag:All> wsag:TermCompositorType </wsag:All> | <wsag:OneOrMore> wsag:TermCompositorType </wsag:OneOrMore> | <wsag:ExactlyOne> wsag:TermCompositorType </wsag:ExactlyOne> | { <wsag:ServiceDescriptionTerm> wsag:ServiceDescriptionTermType </wsag:ServiceDescriptionTerm> | <wsag:ServiceReference> wsag:ServiceReferenceType </wsag:ServiceReference> | <wsag:ServiceProperties> wsag:ServicePropertiesType </wsag:ServiceProperties> | <wsag:GuaranteeTerm> wsag:GuaranteeTermType </wsag:GuaranteeTerm> } * </wsag:Terms> • /wsag:Terms/wsag:All (or wsag:OneOrMore, or wsag:ExactlyOne) • This is a logical AND (or OR, or XOR) operator of type wsag:TermCompositorType • The rest see next page
Individual types • Service description terms • are a fundamental component of an agreement: the agreement is about the service(s) - existing or not - described by the service description terms. • ServiceReference • provides means for an agreement to simply refer to the existing service instance • ServiceProperties • are used to define measurable and exposed properties associated with a service, such as response time and throughput. • GuaranteeTerm • define the assurance on service quality, associated with the service described by the service definition terms. { <wsag:ServiceDescriptionTerm> wsag:ServiceDescriptionTermType </wsag:ServiceDescriptionTerm> | <wsag:ServiceReference> wsag:ServiceReferenceType </wsag:ServiceReference> | <wsag:ServiceProperties> wsag:ServicePropertiesType </wsag:ServiceProperties> | <wsag:GuaranteeTerm> wsag:GuaranteeTermType </wsag:GuaranteeTerm> } *
Service Description Terms • Service description terms (SDTs) are a fundamental component of an agreement: the agreement is about the service(s) - existing or not - described by the service description terms. • May be domain specific • Contains three parts • The name of the ServiceDescriptionTerm. • The name of the service being described partially or fully by the domain-specific part of this service description term. This allows for semantic grouping of service description terms that may not be structurally grouped together in the agreement. • A domain-specific description of the offered or required functionality. This element MAY completely describe the service it is about, or it MAY do so only partially. Agreement Context Terms Compositor Service Description Terms Guarantee Terms <wsag:ServiceDescriptionTerm wsag:Name=”xs:NCName” wsag:ServiceName=”xs:NCName”> <xsd:any> … </xsd:any> </wsag:ServiceDescriptionTerm>
Example of a Service description Term <wsag:All> <wsag:ServiceDescriptionTerm wsag:Name=“executable1" wsag:ServiceName=“a1> <job:executable> /usr/local/job1 </job:executable> </wsag:ServiceDescriptionTerm> <wsag:ServiceDescriptionTerm wsag:Name="numberOfCPUs1" wsag:ServiceName=“a1"> <job:numberOfCPUs>32</job:numberOfCPUs> </wsag:ServiceDescriptionTerm> <wsag:ServiceDescriptionTerm wsag:Name="memoryPerCPU1“ wsag:ServiceName=“a1"> <job:realMemorySize>200</job:realMemorySize> </wsag:ServiceDescriptionTerm> </wsag:All> Specifies a job whose executable is /usr/local/job1 with 32 CPUs and Memory size of 200 (MB?) Please note the usage of Service Name to aggregate several SDT’s.
Service reference: To be added • Any good examples? Extracted from Page 58 Should change ServiceDescriptionTerm To ServiceReference?? <wsag:All> <wsag:ServiceDescriptionTerm wsag:Name="WSDLInterface" wsag:ServiceName="BankingService"> <sdtc:WSDLReference> http://www.foo.org/interfaces/bank.wsdl </sdtc:WSDLReference> </wsag:ServiceDescriptionTerm> <wsag:ServiceDescriptionTerm wsag:Name="WebAccess" wsag:ServiceName="BankingService"> <sdtc:URLPrefixDefinition> http://www.foo.org/bank </sdtc:URLPrefixDefinition> </wsag:ServiceDescriptionTerm> </wsag:All>
Service Properties Sorry ran out of time will translate/update the rest tomorrow.
変数宣言: <wsag:Variable name=”xsd:NCName” metric=”xsd:QName”> … </wsag:Variable> 例えば <wsag:Variable name=”numberOfNodes”> /wsag:Agreement/job:JobDescription</wsag:Variable>
Guarantee Term • サービス品質の規定に関する記述 • 最小のCPU数、メモリ容量、実行時間保証する終了時間など • 以下の3項からなるものの繰り返し • QualifyingCondition: サービスレベルを保障するための前提条件 • 例:サービスを提供する時間(月ー金の定時内) • ServiceLevelObjective: 満たすべきサービスレベル • 応答時間何秒以内とか • BusinessValueList:保障に関するより高度なビジネスレベルの項目 • 費用 • 罰則規定 など Agreement Context Terms Compositor Service Description Terms Guarantee Terms <wsag:GuaranteeTerm> <wsag:QualityingCondition>…</wsag:QualifyingCondition>? <wsag:ServiceLevelObjective>…</wsag:ServiceLevelObjective> <wsag:BusinessValueList>…</wsag:BusinessValueList> </wsag:GuaranteeTerm>
Business Value.. <wsag:BusinessValueList> <wsag:Importance> xsd:integer </wsag:Importance>? <wsag:Penalty> </wsag:Penalty>? <wsag:Reward> </wsag:Reward>? <wsag:BusinessValue> … </wsag:BusinessValue>* </wsag:BusinessValue> <wsag:Penalty> <wsag:AssesmentInterval> <wsag:TimeInterval>xsd:duration</wsag:TimeInterval> | <wsag:Count>xsd:positiveInteger</wsag:Count> </wsag:AssesmentInterval> <wsag:ValueUnit>xsd:string</wsag:ValueUnit>? <wsag:ValueExpr>xsd:any</wsag:ValueExpr> </wsag:Penalty>
Agreement Template Context Terms Compositor Service Description Terms Guarantee Terms Agreement Creation Constraints Agreement Template • Agreementを生成するためにクライエントはAgreement Factoryに、Agreement Templateに基づいたAgreement生成提案を行う。 • Agreement TemplateはAgreement Factoryにより予め、周知されている。 • Agreement templateはAgreementと同じような構造を有するが、更にAgreement Creation Constraintを付加して、合意を得るための条件を指定することが可能である。
Agreement Template Context Terms Compositor Service Description Terms Guarantee Terms Agreement Creation Constraints Agreement Constraintの構成 • 任意個のoffer ItemとConstraintからなる。 <wsag:template> … <wsag:CreationConstraints> ? <wsag:Item>…</wsag:Item> * <wsag:Constraint>…</wsag:Constraint> * </wsag:CreationConstraints> • Offer Item :名前、指定するItemの場所、制限値で指定する <wsag:Item name=”xsd:NCName” location=”xsd:string”> <restriction> xsd:simpleRestrictionModel <restriction> ? </wsag:Item> • Constraint: 任意の制限条件が記述可能 Xqueryを使うことも <wsag:XQueryXConstraint> <wsag:Expression> … </wsag:Expression> </wsag:XQueryXConstraint> <wsag:Constraint/>
PortType <wsag:createAgreementInput> <initiatorAgreementEPR> EPR1 </initiatorAgreementEPR> ? <offer> ... </offer> </wsag:createAgreementInput> <wsag:createAgreementResponse> <createdAgreementEPR> EPR2 </createdAgreementEPR> </wsag:createAgreementResponse> 結果 生成時のInput テンプレートを元に指定されたoffer