Copyright 2005 Digital Enterprise Research Institute. All rights reserved. WSDL-S (LSDIS and IBM) & WSMO file/wssemantic_annotation.pdf.

Copyright 2005 Digital Enterprise Research Institute. All rights reserved.

www.deri.org

WSDL-S (LSDIS and IBM) & WSMO

http://www.alphaworks.ibm.com/g/g.nsf/img/semanticsdocs/$file/wssemantic_annotation.pdf http://lsdis.cs.uga.edu/projects/meteor-s/wsdl-s/

WSMO Working Group PresentationMatthew 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: http://webservices.xml.com/lpt/a/ws/2004/05/19/wsdl2.html)

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: http://webservices.xml.com/lpt/a/ws/2004/05/19/wsdl2.html)

Agnostic to ontology representation language

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WSDL-S XML Schema – WSSemantics.xsd

<?xml version="1.0" encoding="UTF-8"?><schema xmlns="http://www.w3.org/2001/XMLSchema" targetNamespace="http://www.ibm.com/xmlns/stdwip/Web-services/WS-Semantics" xmlns:wssem="http://www.ibm.com/xmlns/stdwip/Web-services/WSSemantics" xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/">

<attribute name="modelReference" type="anyURI" use="optional"/> <attribute name=”schemaMapping” type=”anyURI” use=”optional”/>

<element name=”category” maxOccurs="unbounded"> <complexType> <complexContent> <extension base=”wsdl:documented”> <attribute name="categoryname" type="NCName" use="required"”/> <attribute name="taxonomyURI" type="anyURI" use="required"”/> <attribute name="taxonomyValue" type="String" use="optional"/> <attribute name="taxonomyCode" type="integer" use="optional"/> </extension> </complexContent> </complexType> </element> <element name = "precondition"> <complexType> <complexContent <restriction base="anyType"> <xsd:attribute name=”name” type=”string” /> <attribute name="modelReference" type="anyURI" /> <attribute name="expression" type="string" /> </restriction> </complexContent> </complexType> </element> <element name="effect"> <complexType> <complexContent <restriction base="anyType"> <xsd:attribute name=”name” type=”string” /> <attribute name="modelReference" type="anyURI" /> <attribute name="expression" type="string" /> </restriction> </complexContent> </complexType> </element></schema>

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Input and output elementsSimple 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"/>

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Input and output elementsComplex type

• Annotating complex types

– Bottom Level Annotation: • At leaf element level

– Top Level Annotation: • At complex type level

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Input and output elementsComplex type

• Bottom Level Annotation: using wssem:modelReference

– Bottom Level Annotation: at leaf element level

<complexType name="POItem">

<all>

<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"/>

</all>

</complexType>

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Input and output elementsComplex type

• Top Level Annotation – High level semantic annotation of the complex type

– Either use modelReference attribute or schemaMapping attribute

• Using wssem:modelReference:

<complexType name="POBilling" wssem:modelReference=”POOntology#Billing”>

<all>

<element name="shipToAddress" type="xsd1:POAddress" />

<element name="billToAddress" type="xsd1:POAddress" />

<element name="accountID" type="xsd1:string />"

</all>

</complexType>

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Input and output elementsComplex 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=”http://www.ibm.com/schemaMapping/POAddress.xsl”>

<all>

<element name="recipientInstName" type="string" />

<element name="streetAddr1" type="string" />

…

<element name="zipCode" type="string" />

<element name="country" type="string" />

</all>

</complexType>

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Preconditions and Effects

<interface name="PurchaseOrder"> <operation name="processPurchaseOrder” pattern=wsdl:in-out> <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"/> </operation></interface>

• 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)

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Preconditions and Effects

<interface name="PurchaseOrder"> <operation name="processPurchaseOrder” pattern=wsdl:in-out> <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"/> </operation></interface>

• 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

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Service Categorization

<element name=”category” maxOccurs="unbounded"><complexType>

<complexContent><extension base=”wsdl:interface”/><attribute name=”categoyname” type=”NCName” use=”required”/><attribute name=”taxonomyURI” type=”anyURI” use=”required”/><attribute name="taxonomyValue" type="String" use="optional"/><attribute name="taxonomyCode" type="integer" use="optional"/>

</complexContent></complexType>

</element>

• Category element– Adopted from OWL-S for use with UDDI

• An extension to the WSDL interface element

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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:– http://www.wsmo.org/TR/d13/d13.8/v0.1/d13.8.pdf

– 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)

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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

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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