Purpose

Execute WSDL interfaces to answer user queries.

Procedure

• Identify the information in web services.
  • annotate existing descriptions
• Query that specific information.

  • SELECT ?asin ?title WHERE {
     ?X tns:id "0FWYBWB91M5S26YBE382" ;
        tns:keywords "Semantics" ;
        tns:index "Books" ;
    
        tns:asin ?asin ;
        tns:title ?title }

• Automatically invoke the appropriate service(s).

Connecting SPARQL to XML

•   <ItemAttributes>
       <Title>Learning to Weave, Revised Edition</Title>   
       <Author>Deborah Chandler</Author>                   
       <Author>Debbie Redding</Author>                     
    </ItemAttributes>

•   <xs:element name="Item">
      <xs:complexType spat:SPAT='?book tns:doctitle xpath("aws:Title")...>
        <xs:sequence>
  	<xs:element name="Title" type="xs:string" minOccurs="0"/>
  	<xs:element name="Author" type="xs:string" minOccurs="0" maxOccurs="unbounded"/>
        </xs:sequence>
      </xs:complexType>
    </xs:element>

• 

Identifying information

• Using SPARQL Annotations (SPARQL + XPath) in WSDL:
  • SPARQL: SQL-like RDF query language

    SELECT ?tile WHERE { ?response tnss:doctitle ?title }

  • XPath: identify locations in a document

    aws:ItemSearchResponse/aws:Items/aws:Item/aws:Title

  • WSDL/XSD: associate messages (documents) with services

    <definitions><types><element name="ItemSearchResponse"></element></types>...
        <message name="ItemSearchResponseMsg"/></definitions>

• SPARQL annotations tie RDF data to locations in a Web Services message.

  • <xs:element name="Item" spat:SPAT='?book tns:doctitle xpath("aws:Title")'/>
    

Demo excerpts

PREFIX tnss: <http://webservices.amazon.com/AWSECommerceService/2004-11-10>
SELECT ?asin ?title WHERE {
 ?X tnss:id "0FWYBWB91M5S26YBE382" ;
    tnss:keywords "cola" ;
    tnss:index "Books" ;

    tnss:asin ?asin ;
    tnss:doctitle ?title }

Expressed in SAWSDL

a sawsdl:loweringSchemaMapping:

      <xs:element name="Item">
        <!-- xs:complexType spat:SPAT='?book tns:doctitle xpath("aws:Title") -->
        <xs:complexType sawsdl:loweringSchemaMapping='&AWS;title'>
	  <xs:sequence>
	    <xs:element name="Author" type="xs:string" minOccurs="0" maxOccurs="unbounded"/>
	    <xs:element name="Title" type="xs:string" minOccurs="0"/>
	  </xs:sequence>
	</xs:complexType>
      </xs:element>

points to a document containing the SPDL annotations:

:id       spat:SPAT '?req :id xpath(".")' .
:keywords spat:SPAT '?req :keywords xpath("tns:Keywords") ; :index    xpath("tns:SearchIndex")' .
:asin     spat:SPAT '?book :asin xpath("tns:ASIN")' .
:title    spat:SPAT '?book tns:docTitle xpath("aws:Title")' .

SAWSDL Described

• Semantic Annotations for WSDL
• Candidate Recommendation — tomorrow
• modelReference: association between a WSDL entity and a concept in some semantic model
  • XSD complex types, simple types, elements, and attributes
  • WSDL operations and interfaces
• liftingSchemaMapping and loweringSchemaMapping;, transformation of information from Web Service messages to semantic model
  • XSD elements, complex types and simple types

Tools — Recap

What tools do we have now?

• A way to identify the semantics of web service...
  • information (XSD)
  • operations (WSDL)
  • interfaces (WSDL)
• Query language for querying that information.

Capabilities

What can we do with these tools?

• Query a single service.
• Join those query results with other data in a database.
• Join those query results with other services.
  • orchestration/choreograph

Costs

What does it cost to use these tools?

• Deployment: annotate existing and new WSDL.
• Precise Queries: users (programmers) need to match spelling and structure to get results.
• Control: there may be very expensive ways to answer queries.
  • bookseller title search and book details query
  • - vs -
  • bookseller title search, purchase the book and OCR it

Questions/Discussion

Impressions of the demonstrator.

Applicability to industry today and tomorrow.

Applicability to users today and tomorrow.