1 Workflow Description for Open Hypermedia Systems Sanjay Vivek, David C. De Roure Department of Electronics and Computer Science University of Southampton, UK

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

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

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

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

8 resolver concurrency fault tolerance aggregation DLS distributed architecture QUERY

Linkbase migration Resolver server LINK DATA

Mobile link resolution agents API AGENT

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

12 Current Music IR architecture

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

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

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

16 IBM

17 IBM

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

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

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

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

24 WSFL and workflow concepts(ii)

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

26 Roles in OHS n Every activity is implemented as a Web Service offered by a Web Service provider n The example OHS Model can be described in WSDL as follows:

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

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