 Copyright 2005 Digital Enterprise Research Institute. All rights reserved. WSDL-S (LSDIS and IBM) & WSMO WSMO Working Group Presentation Matthew Moran, Jacek Kopecky, Adrian Mocan 29 June 2005

2 Presentation Overview WSDL-S overview WSDL-S extensions –Input and output elements –Preconditions and effects –Service categorization Relationship of WSDL-S to WSMO/L/X Is WSDL-S suitable for WSMO Grounding? Conclusions

3 WSDL-S Overview It is a means to add semantics inline to WSDL for: –Inputs and outputs –Operations –Service categorization It is agnostic to ontology representation language used –OWL used up to now –No barrier to the use of WSMO Targeted at WSDL 2.0 but can be used for WSDL 1.1 WSDL-S extension is deifined by an XML Schema

4 WSDL-S Overview Adding semantics inline to WSDL abstract definition –Inputs and output messages Annotated with domain concepts –Operations Annotated with preconditions and effects –Service Interface annotated with category information OWL Semantics WSDL Conceptual Model (From:

5 WSDL-S Overview Adding semantics inline to WSDL abstract definition –Inputs and output messages Annotated with domain concepts –Operations Annotated with preconditions and effects –Service Interface annotated with category information WSMO OWL RDF Semantics WSDL Conceptual Model (From: Agnostic to ontology representation language

6 WSDL-S XML Schema – WSSemantics.xsd <schema xmlns=" targetNamespace=" xmlns:wssem=" xmlns:wsdl=" <complexContent <complexContent

7 Input and output elements Simple type The wssem:modelReference attribute denotes a one-to-one mapping between schema element and ontology concept Uses the extensibility of xsd:element <xs:element name= "processPurchaseOrderResponse" type="xs:string wssem:modelReference="POOntology#OrderConfirmation"/>

8 Input and output elements Complex type Annotating complex types –Bottom Level Annotation: At leaf element level –Top Level Annotation: At complex type level

9 Input and output elements Complex type Bottom Level Annotation: using wssem:modelReference –Bottom Level Annotation: at leaf element level <element name="dueDate" type="dateTime" wssem:modelReference=”POOntology#DueDate"/> <element name="quantity" type="float" wssem:modelReference ="POOntology#Quantity"/> <element name="EANCode" type="string" wssem:modelReference ="POOntology#ItemCode"/> <element name="itemDesc" type="string" wssem:modelReference ="POOntology#ItemDesc"/>

10 Input and output elements Complex type Top Level Annotation –High level semantic annotation of the complex type –Either use modelReference attribute or schemaMapping attribute Using wssem:modelReference: "

11 Input and output elements Complex type Top Level Annotation –The XMLSchema type POAddress is mapped using an XSL Transformation to concepts in an ontology Using wssem:schemaMapping: <complexType name="POAddress" wssem:schemaMapping=” …

12 Preconditions and Effects <input messageLabel = ”processPurchaseOrderRequest" element="tns:processPurchaseOrderRequest"/> <output messageLabel ="processPurchaseOrderResponse" element="processPurchaseOrderResponse"/> <wssem:precondition name="ExistingAcctPrecond" wssem:modelReference="POOntology#AccountExists"> <wssem:effect name="ItemReservedEffect“ wssem:modelReference="POOntology#ItemReserved"/> Defined at the level of WSDL operation WSMO defines at the level of service modelReference has a slightly different semantics here (Also possible to define the logical expression inline in WSDL)

13 Preconditions and Effects <input messageLabel = ”processPurchaseOrderRequest" element="tns:processPurchaseOrderRequest"/> <output messageLabel ="processPurchaseOrderResponse" element="processPurchaseOrderResponse"/> <wssem:precondition name="ExistingAcctPrecond" wssem:modelReference="POOntology#AccountExists"> <wssem:effect name="ItemReservedEffect“ wssem:modelReference="POOntology#ItemReserved"/> Defined at the level of WSDL operation WSMO defines at the level of service modelReference has a slightly different semantics here Also possible to define the logical expression inline in WSDL At most one precondition –To keep the specification simple –Complex preconditions should be specified in the domain model As many effects as possible

14 Service Categorization Category element –Adopted from OWL-S for use with UDDI An extension to the WSDL interface element

15 Relationship of WSDL-S to WSMO/L/X WSMO can be used for semantic annotation of WSDL with WSDL-S WSDL-S defines Preconditions and Effects (WSMO postconditions) –Could be extended to include Effects (WSMO) and Assumptions WSMX WG co-operation with the LSDIS lab underway: – –Linking Semantic Web Services Efforts. (Second International Workshop on Semantic and Dynamic Web Processes (SDWP), 2005) There is no mechanism to describe Choreography or Orchestration There is no mechanism to describe Preconditions, Effects etc. for a Web Service as an entity (they are defined at operation level)

16 Usefulness for WSMO Grounding Bottom approach may appeal to those used to WSDL The schemaMapping attribute allows for complex mappings to be identified by a URI The modelReference assumes that the XML Schema and corresponding ontology stay in sync Semantics and syntax are tightly coupled –Different WSDL-S for each ontology language? –WSDL of existing services would have to be modified Seems an incomplete mix of semantics and syntactics –Choreography and Orchestration etc. missing  An additional semantic description still required

17 Conclusion Bottom-up approach –Lightweight and WSDL friendly WSDL for existing services would have to be rewritten –In contrast to WSMO grounding –Semantics and syntax coupled in WSDL-S approach Choreography and Orchestration not addressed –Would still need a second semantic service description Is not WSML –Is not processable by WSMX May be a intermediate approach to adding semantics to Web service descriptions (outside WSMX) DERI and LSDIS have started discussing co-operation