WSMO-Full – Some thoughts Chris Preist

Opening Comments…. OWL-S was feature-driven rather than concept-driven…. The (implicit) conceptual architecture is ‘web services as plan fragments.’ WSMF provides central conceptual pillars, but no conceptual architecture. Let’s make a clear, semi-formal conceptual architecture for WSMO.

What am I presenting? Conceptual architectural model, not features (But still informal, provisional…) The conceptual model can be applied to WSMO-lite, WSMO-std or WSMO-full However, to do it ‘properly’ (in e- commerce) will require extra features beyond either WSMO-std or OWL-S.

Where does the model come from? Use cases developed over several years of analysis of eCommerce case studies. Linked to work in the agent community, and HP’s Service Oriented Architecture work. (e-Speak) Particularly based on analysis of SWWS Case Studies 7 and 8. Weakness: needs input from beyond eCommerce.

What does ‘service’ mean? 1.A ‘good or service’ at the application level: information, train ticket, book, bandwidth provision etc. 2.An ‘agent’ which carries out tasks on behalf of its owner: Amazon book-selling service. (‘e-Service’) 3.A set of WSDL operations which implement some behaviours. (Web service)

‘Semantic e-Services’ For e-Commerce to succeed, we need to annotate e-Services (however they are implemented) with semantics at the application level, and group them according to service provider. This accords with the W3C Web Services Architecture

Messages…. I believe that WSMO needs a clear conceptual architecture to motivate its features Such an architecture should relate to abstract use cases developed from concrete case studies I propose an early version of this

What next…. I am working on SWWS conceptual architecture (Due end April) (Extending W3C-WSA) Based on analysis of the 4 case studies I welcome feedback and input. Particularly example use cases (from case studies) which should be supported by the conceptual architecture. Maybe basis for WSMO architecture?

Use Case Flow (I) Client formulates a goal which needs to be achieved Discovery Phase Client locates Service Providers which may help him to achieve the goal –May include contacting some Service Provider Registry Client contacts some of potential Service Providers Product Definition/Negotiation Phase For each provider: –Client contacts each Service Provider and presents his goal –Provider will ask additional questions about the need of the Client –This may be an iterative process until Client and the Service provider agree on the Product Definition –This phase may involve negotiation as well Client chooses one Service Provider Client makes a contract with the Service Provider

Use Case Flow (II) Delivery Phase Client requests the start of the service During service delivery messages may be exchanged, e.g. to check the status of the service delivery After service is delivered, payment will take place –May also occur before, after, or in stages, depending on the contract

Use Case Addendum To achieve his goal, Client may need to contact several Service Providers –Each service provider is capable of achieving only a part of the Client’s goal Client has to coordinate activities of the Service Providers Each Service Provider uses a different protocol: there is a need for mediation