1 WS-Agreement Tutorial Material 2004/09/13 Toshiyuki Nakata

2 Full Copyright Notice Copyright © Global Grid Forum (2003, 2004). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the GGF or other organizations, except as needed for the purpose of developing Grid Recommendations in which case the procedures for copyrights defined in the GGF Document process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the GGF or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE GLOBAL GRID FORUM DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Intellectual Property Statement The GGF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Copies of claims of rights made available for publication and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the GGF Secretariat. The GGF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights which may cover technology that may be required to practice this recommendation. Please address the information to the GGF Executive Director (see contact information at GGF website).

3 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 25 th 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

4 Address Map summary ( Old to be updated) PrefixNamespace wsag (temporary) wsahttp://schemas.xmlsoap.org/ws/2003/03/addressing wsbf wssg wsrp xs/xsdhttp:// xsihttp:// wsdlhttp://schemas.xmlsoap.org/wsdl/

5 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.

6 Simple Sequnce-1 Agreement InitiatorAgreement Provider GetResourceProperty("AgreementFactory", "wsag:AgreementFactoryProperties") (templates) CreateAgreement(offer) (EPR to Agreement1) Based on the Template create an offer Decide to agree To the offer Create an agreement Agreement1 At this moment the agreement is Observed. A-I cannot refuse to the Created Agreement Not sure what to Put in the parameters..

7 Simple Sequnce-2 Agreement InitiatorAgreement Provider (templates) CreateAgreement(offer) (Return a Fault) Based on the Template create an offer Decide to refuse GetResourceProperty("AgreementFactory", "wsag:AgreementFactoryProperties")

8 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 Name Context Terms Compositor Service Description Terms ServiceReferences ServiceProperties Guarantee Terms

9 Agreement Context /wsag:AgreementContext/AgreementInitiator Agreement Initiator ： （ Requestor ） Can be an URI or wsa:EndpointReference( ＥＰ R) /wsag:AgreementContext/AgreementProvider Provider Can be an URI or wsa:EndpointReference( ＥＰ R) /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??) xs:anyURI xs:DateTime xs:string... Agreement Context Terms Compositor Guarantee Terms PS what is /wsp:Context in page 15? Service Description Terms ServiceReferences ServiceProperties

10 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..

11 Term Composite Structure /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 wsag:TermCompositorType | wsag:TermCompositorType | wsag:TermCompositorType | { wsag:ServiceDescriptionTermType | wsag:ServiceReferenceType | wsag:ServicePropertiesType | wsag:GuaranteeTermType } *

12 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:ServiceDescriptionTermType | wsag:ServiceReferenceType | wsag:ServicePropertiesType | wsag:GuaranteeTermType } *

13 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 … ServiceReferences ServiceProperties

14 Example of a Service description Term /usr/local/job 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.

15 Service reference provides means for an agreement to simply refer to the existing service instance /wsag:ServiceReference/{xsd:any} This element is a domain-specific representation of a reference to a service. Examples: An EPR in an agreement on the performance of an existing Web service Metadata identifying a class of packet headers in an agreement on network Quality of Service). <wsag:ServiceDescriptionTerm wsag:Name="WSDLInterface" wsag:ServiceName="BankingService"> <wsag:ServiceDescriptionTerm wsag:Name="WebAccess" wsag:ServiceName="BankingService"> Extracted from Page 58 Should change ServiceDescriptionTerm To ServiceReference?? …

16 Service Properties ServiceProperties are used to define measurable and exposed properties associated with a service, such as response time and throughput. The properties are used in expressing service level objectives. The key element is the “variable set” shown in the second box. wsag:VariableSetType xsd:anyType //wsag:AgreementOffer/wsag:Terms/wsag:All/wsag:ServiceDefi nitionTerm/job:executable /usr/local/job Location pointed out by Is as pointed by the red arrow, however The concept of numberofCPUs is as pointed by the blue arrow. How do we explain this? Example

17 Guarantee Term define the assurance on service quality, associated with the service described by the service definition terms. Is composed of ServiceScope: the list of services this guarantee applies to. QualifyingCondition: an optional condition that must be met (when specified) for a guarantee to be enforced. ServiceLevelObjective: an assertion expressed over service descriptions. BusinessValueList: one or more business values associated with this objective. Agreement Context Terms Compositor Service Description Terms Guarantee Terms ServiceReferences ServiceProperties … * … ? … I deleted the variables entry (in line 1 page 22) As I assume that it is a leftover from time Before ServiceProperties were Introduced Typo in spec (P.22)

18 Service Scopes, QualifyingCondition and ServiceLevelObjective Service Scopes a list of service names referring to the respective wsag:ServiceName attributes of one or more of the service description terms in this agreement. QualifyingCondition and ServiceLevelObjective are expressed as assertions over service attributes and/or external factors such as date and time. The type of both elements is xsd:anyType as a completely open content that can be extended with assertion languages which MAY be designed independently of the WS-Agreement specification but which MUST address the requirements of the particular domain of application of the agreement. A1 B1

19 Business Value.. xsd:integer ? ? … * wsag:importance Relative terms, such as high, low, medium, etc. can be used to prioritize across many guarantees. However, to provide stronger semantics and easier comparison of this value, this is expressed using an integer. What is the range? 0..10? ? Higher number means Higher Priority? wsag:CustomBusinessValue: Can be added and is completely domain soecific

20 Penalty and Rewards AssesmentInterval This element defines the interval over which a penalty is assessed. TimeInterval This element when present defines the assessment interval as a duration. wsag:Count This element when present defines the assessment interval as a service specific count, such as number of invocation. ValueUnit This element defines the unit for assessing penalty, such as USD. This is an optional element since in some cases a default unit MAY be assumed. ValueExpr This element defines the assessment amount, which can be an integer, a float or an arbitrary domain-specific expression. xsd:duration | xsd:positiveInteger xsd:string ? xsd:any Alternatively, meeting each objective generates a reward for a service provider. The value expression for reward is similar to that of penalty.

21 Preference “Preference” is used to describe a list of fine-granularity business values for different alternatives, where satisfying each alternative results in a different business value. ServiceTermReference This element can appear multiple times each ServiceTermReference references a ServiceTerm representing an alternative for meeting service level objective. Corresponding, utility (specified below) specifies utility in meeting this objective. Utility This element can appear multiple times, one corresponding to each ServiceTermReference. xsd:string * xsd:float * ComputeJob1 numberOfCPUsHigh numberOfCPUsLow numberOfCPUsHigh 0.8 numberOfCPUsLow 0.5 How do we map Utility to ServiceTermReference? What is the Definition of ServiceTerm? Example from Appendix3 in Page 56. Where is SeviceLevelObjective defined in the spec?

22 Agreement Template To create an agreement, a client makes an offer to an agreement factory. An agreement creation offer has the same structure as an agreement. The agreement factory advertises the types of offers it is willing to accept by means of agreement templates. An agreement template is composed of three distinct parts. The structure of an agreement template is the same as that of an agreement, but an Agreement template MAY also contain a creation constraint section, i.e. a section with constraints on possible values of terms for creating an agreement. Agreement Template Context Terms Compositor Agreement Creation Constraints Service Description Terms Guarantee Terms

23 Config. Of Agreement Constraint Is composed of a number of offer Item and Constraint Offer Item : is specified by name, Item location and restriction A restriction applies to the value that can be filled in by an agreement initiator at the specified location at agreement creation time. If all filled in values adhere to their respective restriction an agreement is compliant with its template … ? … * Agreement Template Conte xt Terms Compositor Agreement Creation Constraints Service Description Terms Guarantee Terms <wsag:Item name=”xsd:NCName” location=”xsd:string”> xsd:simpleRestrictionModel ? Constraint ： Free-form constraints make it possible to restrict the possible values of the term set of an offer beyond restrictions of individual terms. …

24 PortType EPR1 ?... Input EPR2 Result