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Workflow Description for Open Hypermedia Systems

Workflow Description for Open Hypermedia Systems. Sanjay Vivek, David C. De Roure smv99r@ecs.soton.ac.uk Department of Electronics and Computer Science University of Southampton, UK. Outline. Brief history of third party link services What is workflow? Web Services and OHS

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Workflow Description for Open Hypermedia Systems

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  1. Workflow Description for Open Hypermedia Systems Sanjay Vivek, David C. De Roure smv99r@ecs.soton.ac.uk Department of Electronics and Computer ScienceUniversity of Southampton, UK

  2. Outline • Brief history of third party link services • What is workflow? • Web Services and OHS • Web Services Flow Language(WSFL) and workflow concepts • Roles in OHS • Recursive composition • Summary and Discussion

  3. Simple Open Hypermedia architecture Separable hyperstructure Link database Note the direction of this arrow! documents

  4. Open Hypermedia as a Link Service Documents in native format Hypermedia Link service Query (before, during or after doc is delivered) Customised hypermedia documents

  5. Proxy DLS Proxy DLS client Internet The ‘Proxy DLS’ is an HTTP proxy that inserts links on-the-fly by querying the link service Link service

  6. DLS distributed architecture QUERY resolver aggregation resolver resolver resolver concurrency fault tolerance resolver

  7. Linkbase migration server Resolver LINK DATA Resolver server Resolver

  8. Mobile link resolution agents AGENT API API API API API

  9. Link-enabled Application LINK Music content-based navigation Available Links Interface Link Manager Feature Extractor Feature Matching + Retrieval Link Service D.L.S. Streaming media using RTSP over IPv6 Feature Agents Digital Library Feature Database Link Database

  10. Current Music IR architecture

  11. But where does link data come from? DIY slide - Please label the boxes yourself 

  12. Overview • Introduce workflow support for OHS • Expose these OHS components as Web Services • Enable integration and coordination with Web Services Flow Language (WSFL)

  13. What is workflow? • Workflow deals with the management, specification, and execution of operations (business processes) in organizations

  14. IBM

  15. IBM

  16. Agent Technology: A Canonical View Agent Interactions Organisational relationships Environment Sphere of influence Jennings, CACM

  17. WSFL and workflow concepts • XML language for the description of Web Services compositions • Essentially a specification to implement a business process model • Uses a workflow engine like the MQSeries Workflow to consume WSFL

  18. <globalModel name="bookTripNTickets" serviceproviderType="agentType"> <serviceProvider name="travelAgent" serviceProviderType="tio:agentType"> <export> <source portType="tio:tripHandler" operation="sendItinerary"/> <target portType="tio:tripNTicketHandler" operation="sendItinerary"/> </export> <export> <source portType="tio:tripHandler" operation="receiveTripOrder"/> <target portType="tio:tripNTicketHandler" operation="receiveTripOrder"/> </export> <locator type="..." /> </serviceProvider>

  19. Web Services and OHS(i) • To simplify the development and integration of distributed hypermedia services over the network • Web services enable you to loosely couple processes • Workflow helps integrate new and existing services • Previous work (Haake) in CSCW context rather than web services

  20. Web Services and OHS(ii) • An example OHS model consists of the client, a link service, and a linkbase • OHS components are clearly defined and can be described as a Web Service • Workflow helps sequence, coordinate, and manages conversations among Web services

  21. WSFL and workflow concepts(ii)

  22. WSFL and workflow concepts(ii) • Each box is an activity and is a WebService • Processing logic is indicated by the directed edges • Control points ensure if certain conditions are met before processing the next activity

  23. Roles in OHS • Every activity is implemented as a Web Service offered by a Web Service provider • The example OHS Model can be described in WSDL as follows: <serviceProvider name =”Client” type=”client”/> <serviceProvider name =”Linkservice” type=”linkservice”/> <serviceProvider name=”Linkbase” type=”linkbase”/>

  24. Recursive Composition • Enables service providers to combine services into a single solution • The end user will see the Web Service as a single entity and not as a composite of web services

  25. Summary and Discussion • Deploy OHS services within a Web Service architecture and the usage of WSFL for coordination and interoperability • Two areas of possible research interest • Application Interaction • Reliability of services • Should the OHS community be defining “OHP” in web services?

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