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Web Services over the Grid - WSRF -

Web Services over the Grid - WSRF -. Enrique de Andrés Saiz. Outline. Generic Web Services problem Web Services Resource Framework (WSRF) WS-Addressing Faults Declaring WS-Resource properties Operations over WS-Resource properties WS-Resource lifetime Grouping services

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Web Services over the Grid - WSRF -

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  1. Web Services over the Grid- WSRF - Enrique de Andrés Saiz

  2. Outline • Generic Web Services problem • Web Services Resource Framework (WSRF) • WS-Addressing • Faults • Declaring WS-Resource properties • Operations over WS-Resource properties • WS-Resource lifetime • Grouping services • Developing WSRF services • WSRF::Lite • wsrf4egee Web Services over the Grid

  3. Generic Web Services problem • Generic Web Services are limited by the timeouts of the servers that hosts them: • It is not possible to run long time operations • Solution: • Provide asynchronous behavior to the operations of Web Services. • Requirements: • Any kind of data persistence between invocations to the same instance of a Web Service. • A way to uniquely identify instances of Web Services. • Generic Web Services are stateless… they don’t accomplish these requirements. Web Services over the Grid

  4. Inputs Outputs myOp username password … … Inputs Outputs Inputs Outputs Inputs Outputs myOp_submit myOp_status myOp_result username username username … password password password id … Example • Imagine we have a Web Service with operations that: • Require a lot of time to be executed • Require valid credentials to execute them Web Services over the Grid

  5. Inputs Outputs createSession id Inputs Outputs myOp_submit username password username Inputs Inputs Outputs Outputs Outputs Inputs password … myOp_status myOp_result myOp_result username username … … password password id Example Web Services over the Grid

  6. Solving the problem… • Approach 1: • Your own solution as the previous example. • Problems: • Using a parameter for identifying the instance of the Web Services. • No very clear how to get data persistence. • Approach 2: • USING STANDARS. • WSRF (Web Services Resources Framework) defines a generic framework for modeling and accessing persistent resources using Web Services: • It makes easier the definition and implementation of a service and the integration and management of multiple services Web Services over the Grid

  7. Outline • Generic Web Services problem • Web Services Resource Framework (WSRF) • WS-Addressing • Faults • Declaring WS-Resource properties • Operations over WS-Resource properties • WS-Resource lifetime • Grouping services • Developing WSRF services • WSRF::Lite • wsrf4egee Web Services over the Grid

  8. Web Services Resource Framework, WSRF • WSRF is an OASIS standard that can be used to implement interoperable stateful web-services. • WSRF is a set specifications that define what is termed the WS-Resource approach to modeling and managing state in a Web services context. • WSRF uses the W3C standard WS-Addressing to achieve transport-neutral addressing for web-services. Web Services over the Grid

  9. Web Services Resource Framework, WSRF • The central element of WSRF standard is the concept of WS-Resource. • A WS-Resource is the logical entity which stores (persistent) information: • A WS-Resource has defined resource properties: • A resource property is a piece of information defined as part of the state model of a WS-Resource. • A WS-Resource can be accessed through defined message exchanges or operations for: • Accessing resource properties. • Interact with the WS-Resource lifetime. • A WS-Resource is associated to a Web Service instance. • When creating a new service instance, a new WS-Resource is created. • WSRF uses WS-Addressing specification for uniquely identify a WS-Resource (or a Web Service instance). • A reference to a WS-Resource is represented by an endpoint reference (EPR). Web Services over the Grid

  10. Example Simple shopping service example • We have a shopping carts that store one product (WS-Resource) per cart. • A product (WS-Resource) have defined a set of properties (WS-Resource Properties): • ProductCode • Description • Quantity • ProductPrice • It is possible to interact with the properties of the product (Operations over WS-Resource Properties). • It is possible to delete a shopping cart (Operations over WS-Resource Lifetime). Web Services over the Grid

  11. Using WSRF for the Grid • One WS-Resource corresponds to one job on the Grid • WS-Resource properties: • Input data/parameters of the job (or the application executed by the job). • Output data of the job. • Any other data required. • WS-Resource operations: • Operations over the resource properties. • Operations over the resource lifetime. • Other specific operations for the Grid. • Grid requirements: • All operations over the Grid must be executed as an authenticated user in the User Interface. • Operation mode must be asynchronous (edg-job-submit, edg-job-status, edg-jog-get-output). • It is not necessary to create an asynchronous behavior, only move it from the Grid to the WSRF services. Web Services over the Grid

  12. createResource(username, password) EPR – Resource ID SetResourceProperty(myName) submitJob() GetResourceProperty(status) collectResults() GetMultipleResourceProperties(stdout, stderr, response) Destroy() Simple Hello World Grid WSRF service GridHello World WS-Resource username username password password myName myName status status response response stdout stdout stderr stderr Web Services over the Grid

  13. Outline • Generic Web Services problem • Web Services Resource Framework (WSRF) • WS-Addressing • Faults • Declaring WS-Resource properties • Operations over WS-Resource properties • WS-Resource lifetime • Grouping services • Developing WSRF services • WSRF::Lite • wsrf4egee Web Services over the Grid

  14. WS-Addressing • The key concept in WS-Addressing is the Endpoint Reference (EPR): • An EPR is a URL wrapped by some XML elements which represents the location of a Web Service: • An EPR allows to include additional information in a SOAP request that helps uniquely identify a Web Service instance • EPR’s are used by WSRF for representing references to WS-Resources. • EPR’s vs. URL’s. Why EPR’s are necessary? • Appending something like ?resourceID=123 to the URL is not very SOAP-ish. • It’s better to use additional SOAP headers. • Web Service specific data is not bound to one specific transport protocol. • Web Service specific data is all inside the SOAP envelope (not in different levels, one at the transport level and other at SOAP level). Web Services over the Grid

  15. WS-Addressing • Endpoint Reference format: • wsa:Address • Specifies the URL that should be used when trying to talk to the Web Service. • wsa:ReferenceProperties • Encapsulates all Web service-specific data (reference properties), such as a session identifier, an instance identifier or a resource identifier. <widget:myLocationEPR> <wsa:Address>http://localhost/WidgetService</wsa:Address> <wsa:ReferenceProperties> <widget:resourceID>123</widget:resourceID> </wsa:ReferenceProperties> </widget:myLocationEPR> Web Services over the Grid

  16. WS-Addressing • An EPR should be returned at some point of a Web Service: • When creating an instance to the Web Service. • Asking for a pointer to an instance to the Web Service. <soap:Envelope...> <soap:Body> <widget:createWidgetResponse...> <widget:widgetReference> <wsa:Address>http://host/WidgetService</wsa:Address> <wsa:ReferenceProperties> <widget:resourceID>123</widget:resourceID> </wsa:ReferenceProperty> </widget:widgetReference> </widget:createWidgetResponse> </soap:Body> </soap:Envelope> Web Services over the Grid

  17. WS-Addressing • Subsequent invocations to the instance of a Web Service referred by an EPR must integrate the information of that EPR in the SOAP header: • wsa:To • SOAP message information header which indicates the target Web Service’s URL. • It should be the same value as the wsa:Address element of the associated EPR. <soap:Envelope...> <soap:Header> <wsa:To> http://host/WidgetService </wsa:To> <widget:resourceID>123</widget:resourceID> </soap:Header> <soap:Body> ... </soap:Body> </soap:Envelope> Web Services over the Grid

  18. WS-Addressing • Other SOAP message information headers: • wsa:From • Indicates the EPR of the message's sender. • If the message's receiver needs to send a message back to the endpoint that sent the message, then it should use this EPR. • wsa:ReplyTo • Indicates the EPR to where the response message should go. <wsa:From> <wsa:Address> http://client/myClient </wsa:Address> </wsa:From> <wsa:ReplyTo> <wsa:Address> http://client/myReceiver </wsa:Address> </wsa:ReplyTo> Web Services over the Grid

  19. WS-Addressing • …other SOAP message information headers: • wsa:FaultTo: • Indicates the EPR to where a fault should go if the response to a message is a SOAP fault. • wsa:MessageID: • Is a URI that uniquely identifies a message. • wsa:Action: • Makes reference to the operation that must be carried out. <wsa:FaultTo> <wsa:Address> http://client/FaultCatcher </wsa:Address> </wsa:FaultTo> <wsa:MessageID>uuid:098765</wsa:MessageID> <wsa:Action> http://host/widgetOp </wsa:Action> Web Services over the Grid

  20. WS-Addressing • …other SOAP message information headers: • wsa:RelatesTo: • Is used on response messages to indicate that it is related to a previously-known message and to define that relationship. • In all of the headers that either contain an Address element or are, like the To header, an address themselves, you can use a special anonymous URI: • http://schemas.xmlsoap.org/ws/2003/03/addressing/role/anonymous • Indicates that there is no real endpoint available for this address. <wsa:RelatesTo RelationshipType="wsa:Response"> uuid:098765 </wsa:RelatesTo> Web Services over the Grid

  21. Outline • Generic Web Services problem • Web Services Resource Framework (WSRF) • WS-Addressing • Faults • Declaring WS-Resource properties • Operations over WS-Resource properties • WS-Resource lifetime • Grouping services • Developing WSRF services • WSRF::Lite • wsrf4egee Web Services over the Grid

  22. Base faults • WSRF defines a set of rules for exchanging faults messages through WS-BaseFaults specification. • WS-BaseFaults defines a XML schema type for a base fault. • The base fault has the following syntax: <BaseFault> {any}* <Timestamp>xsd:dateTime</Timestamp> <OriginatorReference> wsa:EndpointReferenceType </OriginatorReference> ? <ErrorCode dialect="anyURI">xsd:anyType</ErrorCode> ? <Description>xsd:string</Description> * <FaultCause>{any}</FaultCause> ? </BaseFault> Web Services over the Grid

  23. Faults • All faults must use the following URI inside the wsa:Action • http://docs.oasis-open.org/wsrf/fault • A WSRF service supports the following base faults: • ResourceUnknownFault • The resource identified in the message is not known to the Web service. • ResourceUnavailableFault • The resource identified in the message is unavailable. Web Services over the Grid

  24. Faults Example SOAP 1.1 Encoding of a Base Fault Web Services over the Grid

  25. Outline • Generic Web Services problem • Web Services Resource Framework (WSRF) • WS-Addressing • Faults • Declaring WS-Resource properties • Operations over WS-Resource properties • WS-Resource lifetime • Grouping services • Developing WSRF services • WSRF::Lite • wsrf4egee Web Services over the Grid

  26. Declaring WS-Resource Properties • One characteristic of a WS-Resource is the set of properties associated with the resource. • The definition of the properties of a WS-Resource MAY be declared as part of a Web Service interface: • The declaration of the WS-Resource’s properties represents a projection of a view of the WS-Resource’s state. • This projection is defined in terms of a resource properties document: • The resource properties document definition is associated with a Web service WSDL portType in the following manner: <wsdl:defintions …> <wsdl:portType … wsrf-rp:ResourceProperties=”xsd:QName”? … > … </wsdl:portType> Web Services over the Grid

  27. Declaring Resource Properties WSDL example Web Services over the Grid

  28. Outline • Generic Web Services problem • Web Services Resource Framework (WSRF) • WS-Addressing • Faults • Declaring WS-Resource properties • Operations over WS-Resource properties • WS-Resource lifetime • Grouping services • Developing WSRF services • WSRF::Lite • wsrf4egee Web Services over the Grid

  29. Operations over WS-Resource Properties • WSFR defines a standard set of message exchanges or operations that allow a requestor to query or update the property values of a WS-Resource: • GetResourcePropertyDocument (optional) • GetResourceProperty (mandatory) • GetMultipleResourceProperties (optional) • QueryResourceProperties (optional) • PutResourcePropertyDocument (optional) • SetResourceProperties (optional) • InsertResourceProperties (optional) • UpdateResourceProperties (optional) • DeleteResourceProperties (optional) Web Services over the Grid

  30. GetResourcePropertyDocument • Allows a requestor to retrieve the values of all resource properties associated with the WS-Resource. • Request: • wsa:Action=http://docs.oasis-open.org/wsrf/rpw-2/GetResourcePropertyDocument/GetResourcePropertyDocumentRequest • Response: • wsa:Action=http://docs.oasis-open.org/wsrf/rpw-2/GetResourcePropertyDocument/GetResourcePropertyDocumentResponse • Faults: • Generic WS-Resource faults. <wsrf-rp:GetResourcePropertyDocument /> <wsrf-rp:GetResourcePropertyDocumentResponse> {any} </wsrf-rp:GetResourcePropertyDocumentResponse> Web Services over the Grid

  31. Resource properties document Response Request GetResourcePropertyDocument Web Services over the Grid

  32. GetResourceProperty • Allows a requestor to retrieve the value of a single resource property of a WS-Resource. • Request: • wsa:Action=http://docs.oasis-open.org/wsrf/rpw-2/GetResourceProperty/GetResourcePropertyRequest • Response: • wsa:Action=http://docs.oasis-open.org/wsrf/rpw-2/GetResourceProperty/GetResourcePropertyResponse <wsrf-rp:GetResourceProperty> QName </wsrf-rp:GetResourceProperty> <wsrf-rp:GetResourcePropertyResponse> {any}* </wsrf-rp:GetResourcePropertyResponse> Web Services over the Grid

  33. GetResourceProperty • Faults: • Generic WS-Resource faults. • InvalidResourcePropertyQNameFault: • The QName in the request message did not correspond to a resource property element of the WS-Resource referred to in the request message. Web Services over the Grid

  34. Request Response GetResourceProperty Web Services over the Grid

  35. GetMultipleResourceProperties • Allows a requestor to retrieve the values of multiple resource properties of a WS-Resource. • Request: • wsa:Action=http://docs.oasis-open.org/wsrf/rpw-2/GetMultipleResourceProperties/GetMultipleResourcePropertiesRequest • Response: • wsa:Action=http://docs.oasis-open.org/wsrf/rpw-2/GetMultipleResourceProperties/GetMultipleResourcePropertiesResponse <wsrf-rp:GetMultipleResourceProperties> <wsrf-rp:ResourceProperty>QName<wsrf-rp:ResourceProperty>+ </wsrf-rp:GetMultipleResourceProperties> <wsrf-rp:GetMultipleResourcePropertiesResponse> {any}* </wsrf-rp:GetMultipleResourcePropertiesResponse> Web Services over the Grid

  36. GetMultipleResourceProperties • Faults: • Generic WS-Resource faults. • InvalidResourcePropertyQNameFault: • One or more of the QNames in the request message did not correspond to a resource property element of the WS-Resource referred to in the request message. Web Services over the Grid

  37. Request Response GetMultipleResourceProperties Web Services over the Grid

  38. QueryResourceProperties • Allows a requestor to query the resource properties document of a WS-Resource using a query expression such as XPath. • Supporting XPath dialect is mandatory: • http://www.w3.org/TR/1999/REC-xpath-19991116 • Request: • wsa:Action=http://docs.oasis-open.org/wsrf/rpw-2/QueryResourceProperties/QueryResourcePropertiesRequest • Response: • wsa:Action=http://docs.oasis-open.org/wsrf/rpw-2/QueryResourceProperties/QueryResourcePropertiesResponse <wsrf-rp:QueryResourceProperties> <wsrf-rp:QueryExpression Dialect=”xsd:anyURI”> xsd:any </wsrf-rp:QueryExpression> </wsrf-rp:QueryResourceProperties> <wsrf-rp:QueryResourcePropertiesResponse> {any} </wsrf-rp:QueryResourcePropertiesResponse> Web Services over the Grid

  39. QueryResourceProperties • Faults: • Generic WS-Resource faults. • UnknownQueryExpressionDialectFault • The given QueryExpression has a dialect that is unknown to the Web service. • InvalidQueryExpressionFault • The given QueryExpression is not valid within the QueryExpression language identified by the dialect attribute. Web Services over the Grid

  40. Request Response QueryResourceProperties Web Services over the Grid

  41. PutResourcePropertyDocument • Allows a requestor to completely replace the values of a WS-Resource’s properties with an entirely new resource property document. • Request: • wsa:Action=http://docs.oasis-open.org/wsrf/rpw-2/PutResourcePropertyDocument/PutResourcePropertyDocumentRequest • Response: • wsa:Action=http://docs.oasis-open.org/wsrf/rpw-2/PutResourcePropertyDocument/PutResourcePropertyDocumentResponse <wsrf-rp:PutResourcePropertyDocument> {any} </wsrf-rp:PutResourcePropertyDocument> <wsrf-rp:PutResourcePropertyDocumentResponse> {any} ? </wsrf-rp:PutResourcePropertyDocumentResponse> Web Services over the Grid

  42. PutResourcePropertyDocument • Faults: • Generic WS-Resource faults. • UnableToPutResourcePropertyDocumentFault • The WS-Resource was unable to complete the processing of the PutResourcePropertyDocument for some reason. Web Services over the Grid

  43. Request Response PutResourcePropertyDocument Web Services over the Grid

  44. SetResourceProperties • Allows the processing of a single request message to make multiple changes to the resource properties document. • Types of changes: • Insert: • wherein a new resource property element is inserted into the resource properties document • Update: • wherein existing resource property element(s) are modified • Delete: • wherein existing resource property element(s) are removed Web Services over the Grid

  45. SetResourceProperties • Request: • wsa:Action=http://docs.oasis-open.org/wsrf/rpw-2/SetResourceProperties/SetResourcePropertiesRequest • Response: • wsa:Action=http://docs.oasis-open.org/wsrf/rpw-2/SetResourceProperties/SetResourcePropertiesResponse <wsrf-rp:SetResourceProperties> [ <wsrf-rp:Insert > {any}* </wsrf-rp:Insert> | <wsrf-rp:Update > {any}* </wsrf-rp:Update> | <wsrf-rp:Delete ResourceProperty=”QName” /> ]+ </wsrf-rp:SetResourceProperties> <wsrf-rp:SetResourcePropertiesResponse> </wsrf-rp:SetResourcePropertiesResponse> Web Services over the Grid

  46. SetResourceProperties • Faults: • Generic WS-Resource faults. • InvalidModificationFault • The contents of the SetResourceProperties request component cause the resource properties document to no longer be able to validate. • UnableToModifyResourcePropertyFault • A resource property identified by one of the SetResourceProperties request components is read-only. • InvalidResourcePropertyQNameFault • A resource property QName does not identify a resource property. • SetResourcePropertyRequestFailedFault • One or more components of the SetResourceProperties request failed. Web Services over the Grid

  47. SetResourceProperties • Any fault message indicating a failure during the update of the resource properties document must also indicate whether the document was restored or not by using the ResourcePropertyChangeFailure element of the fault: • Indicates the resource property element change associated with the fault. • Indicates if the resource property document as a whole was restored <wsrf-rp:ResourcePropertyChangeFailure Restored=xsd:boolean?> <wsrf-rp:CurrentValue>{any}*</wsrf-rp:CurrentValue> ? <wsrf-rp:RequestedValue>{any}*</wsrf-rp:RequestedValue> ? </wsrf-rp:ResourcePropertyChangeFailure> Web Services over the Grid

  48. Request Change failure Response SetResourceProperties Web Services over the Grid

  49. InsertResourceProperties • Request the insertion of one or more element values of a single resource property into the resource properties document of a WS-Resource. • Request: • wsa:Action=http://docs.oasis-open.org/wsrf/rpw-2/InsertResourceProperties/InsertResourcePropertiesRequest. • Response: • wsa:Action=http://docs.oasis-open.org/wsrf/rpw-2/InsertResourceProperties/InsertResourcePropertiesResponse. <wsrf-rp:InsertResourceProperties> <wsrf-rp:Insert> {any}* </wsrf-rp:Insert> </wsrf-rp:InsertResourceProperties> <wsrf-rp:InsertResourcePropertiesResponse> </wsrf-rp:InsertResourcePropertiesResponse> Web Services over the Grid

  50. InsertResourceProperties • Faults: • Generic WS-Resource faults. • InvalidModificationFault • The contents of the InsertResourceProperties request component cause the resource properties document to no longer be able to validate. • UnableToModifyResourcePropertyFault • A resource property identified by the InsertResourceProperties request is not modifiable. • InvalidResourcePropertyQNameFault • A resource property QName does not identify a resource property. • InsertResourcePropertiesRequestFailedFault • The InsertResourceProperties request failed for some reason. • Use the ResourcePropertyChangeFailure element of the fault if failure during the update. Web Services over the Grid

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