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Web Service Resource Framework

Web Service Resource Framework. http :// www.globus.org/wsrf / WS-Addressing: http://msdn.microsoft.com/library/en-us/dnglobspec/html/ws-addressing.asp. WSMO Presentation Jos de Bruijn Digital Enterprise Research Institute jos.de-bruijn@deri.ie. Agenda. WSRF WS-Addressing

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Web Service Resource Framework

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  1. Web Service Resource Framework http://www.globus.org/wsrf/ WS-Addressing: http://msdn.microsoft.com/library/en-us/dnglobspec/html/ws-addressing.asp WSMO Presentation Jos de Bruijn Digital Enterprise Research Institute jos.de-bruijn@deri.ie

  2. Agenda • WSRF • WS-Addressing • How WS-Resource works • Implied Resource Pattern • WS-Resource lifecycle • WS-Resource vs. WS-Context • WS-Resource for WSMO? Jos de Bruijn jos.de-bruijn@deri.ie

  3. WSRF • Mainly an IBM effort, together with the Globus Alliance and HP • Standardization through Global Grid Forum and OASIS • Enables discovery of, introspection on and interaction with stateful resources • Is based on OGSI (Open Grid Services Infrastructure), using current developments in Web Services standards [remark: not including WS-CAF] • WSRF distinguished between a stateless Service and stateful Resources, acted upon by that Service Jos de Bruijn jos.de-bruijn@deri.ie

  4. Web Service Resource Framework • A set of six standards, of which only three have been released: • WS-ResourceProperties: • how a Web Service interface relates to a WS-Resource • WS-ResourceLifetime • lifetime management of WS Resources • WS-Notification • event subscription and notification • Unreleased: • WS-RenewableReference • retrieving updates of invalid endpoint references • WS-ServiceGroup • heterogeneous collections of Web Services • WS-BaseFaults • faults / error messages Jos de Bruijn jos.de-bruijn@deri.ie

  5. WS-Addressing • Defines XML elements to identify endpoints and secure end-to-end endpoint identification • Independent of underlying transport mechanism <wsa:EndpointReference> <wsa:Address> http://someOrg.com/aWebService </wsa:Address> <wsa:ReferenceProperties> <tns:resourceID> C </tns:resourceID> </wsa:ReferenceProperties> </wsa:EndpointReference> • Within WSRF, the endpoint reference is a pointer to a web service, constrained to the context of a specific WS-Resource; the context is opaque to the requestor • WS-Addressing states that ReferenceProperties elements must appear as SOAP header elements in messages sent to the service Jos de Bruijn jos.de-bruijn@deri.ie

  6. Some slides copied from the presentation: Bringing Grid & Web Services Together dr. Daniel Sabbah http://www.globus.org/wsrf/sabbah_wsrf.ppt Jos de Bruijn jos.de-bruijn@deri.ie

  7. The WS-Resource framework model Web Service Run-time environment WSDL Interface Web Service Jos de Bruijn jos.de-bruijn@deri.ie

  8. The WS-Resource framework model Invoking a Web Service Endpoint Reference Run-time environment message Interface Web Service message address Jos de Bruijn jos.de-bruijn@deri.ie

  9. The WS-Resource framework model • What is a WS-Resource • Examples of WS-Resources: • Physical entities (e.g.. processor, communication link, disk drive) or Logical construct (e.g.. agreement, running task, subscription) • Real or virtual • Static (long-lived, pre-existing) orDynamic (created and destroyed as needed) • Simple (one), or Compound (collection) • Unique (for the Web Service) - Has a distinguishable identity and lifetime • Stateful - Maintains a specific state that can be materialized using XML • May be accessed through one or more Web Services resource Jos de Bruijn jos.de-bruijn@deri.ie

  10. context The WS-Resource framework model Using a Web service to access a WS-Resource Endpoint Reference Run-time environment id resource id Interface Web Service message message id address Jos de Bruijn jos.de-bruijn@deri.ie

  11. context The WS-Resource framework model Using a Web service to access a WS-Resource Endpoint Reference Endpoint Reference Run-time environment id resource Interface Web Service message message id resource address id Jos de Bruijn jos.de-bruijn@deri.ie

  12. id address The WS-Resource framework model Creating / Locating a WS-Resource Endpoint Reference Endpoint Reference Run-time environment Endpoint Reference resource Interface Web Service message message address Web Service either locates or creates a WS-Resource Jos de Bruijn jos.de-bruijn@deri.ie

  13. Implied Resource Pattern • Ensures data encapsulation • Describes the way WS-Addressing is used to associate a stateful resource with the execution of message exchanges implemented by a web service. • A WS-Addressing EndpointReference must include a ReferenceProperties element, which identifies the resource to be associated with the execution of all message exchange performed using this EndpointReference • The stateful resource associated with a given message exchange is treated as implicit execution context for the message request • The WS-Resource context is managed by the Web Service Jos de Bruijn jos.de-bruijn@deri.ie

  14. WS-Resource lifecycle • Actual creation and destruction and hidden from the requestor • WS-Resources created by WS-Resource factories (cf. factory design pattern) • WS-Resources are identified using a WS-Resource qualified endpoint reference • WS-Resources can be destroyed explicitly by a call from the requestor or after a certain time-out Jos de Bruijn jos.de-bruijn@deri.ie

  15. WS-Resource properties • The state of a WS-Resource is expressed as an XML resource property document • Requestor can query and modify state through WS message exchanges (e.g. using WS-MetaDataExchange) • The resource property document is referred to in the WSDL document • Provide can determine how much of the state of the resource to make visible Jos de Bruijn jos.de-bruijn@deri.ie

  16. WS-Resource vs. WS-Context • Very interesting email thread on WS-Resource vs. WS-Context (part of WS-CAF): http://www-unix.gridforum.org/mail_archive/ogsi-wg/2004/01/threads.html#00014 • WS-Resource seems to ignore WS-Context • WS-Context provides a context independent of the service; WS-CTX relates messages with each other • WS-Resource provides one endpoint reference (using WS-Addressing) for a resource, which is to be sent to the Web Service, when invoking • WS-CTX is used for providing a context for message, without caring what this means; WS-Resource indicates how to retrieve a specific resource; in this sense they are orthogonal Jos de Bruijn jos.de-bruijn@deri.ie

  17. WS-Resource for WSMO • Message exchanges in WSMO are stateful • It seems to make sense to use WS-Resource in the grounding in the choreography • State of a conversation in WS-Resource? • We should have a closer look at WS-Context Jos de Bruijn jos.de-bruijn@deri.ie

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