A Question:

What are the titles and pages of some books on Weaving?

PREFIX aws: <http://dev.w3.org/cvsweb/perl/modules/W3C/SPDL/descriptions/AWSECommerceService-SAWSDL-item-terms.ttl#>
SELECT ?title ?page WHERE {
_:b aws:devID "0FWYBWB91M5S26YBE382" ;
    aws:keywords "Weaving" ;
    aws:index "Books" ;

    aws:asin ?asin ;
    aws:title ?title ;
    aws:page ?page . }

Finding the Answer

• Amazon Book Search service operations ItemSearch and ItemLookup
• ItemLookup(ItemSearch("0FWYBWB91M5S26YBE382", "Weaving", "Books"))

The machine will discover and execute this for us...

Finding the Answer

... and generate requests:

<?xml version="1.0" encoding="UTF-8"?>
<SOAP-ENV:Envelope
  xmlns:xsi="http://www.w3.org/1999/XMLSchema-instance"
  xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/"
  xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
  xmlns:xsd="http://www.w3.org/1999/XMLSchema"
  SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
    <SOAP-ENV:Body>
        <ItemSearch xmlns="">
            <SubscriptionId xsi:type="xsd:string">0FWYBWB91M5S26YBE382</SubscriptionId>
            <Request>
                <Keywords xsi:type="xsd:string">Weaving</Keywords>
                <SearchIndex xsi:type="xsd:string">Books</SearchIndex>
            </Request>
        </ItemSearch>
    </SOAP-ENV:Body>
</SOAP-ENV:Envelope>

Finding the Answer

... and parse responses:

<?xml version="1.0" encoding="UTF-8"?>
<SOAP-ENV:Envelope
  <SOAP-ENV:Body>
    <ItemSearchResponse xmlns="http://webservices.amazon.com/AWSECommerceService/2005-10-05">
      <Items>
        <Item>
          <ASIN>1883010039</ASIN>
          <DetailPageURL>http://www.amazon.com/exec/obidos/redirect?tag=ws%26link_code=sp1%26camp=2025%26creative=165953%26path=http://www.amazon.com/gp/redirect.html%253fASIN=1883010039%2526tag=ws%2526lcode=sp1%2526cID=2025%2526ccmID=165953%2526location=/o/ASIN/1883010039%25253FSubscriptionId=0FWYBWB91M5S26YBE382</DetailPageURL>
          <ItemAttributes>
            <Author>Deborah Chandler</Author>
            <Author>Debbie Redding</Author>
            <ProductGroup>Book</ProductGroup>
            <Title>Learning to Weave, Revised Edition</Title>
          </ItemAttributes>
        </Item>
        ...

SPARQL Annotations: SPAT

Identifying information

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

    SELECT ?tile WHERE { ?response aws: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 aws:doctitle xpath("aws:Title")'/>
      

Operation Rules

• Model information in Input and Output as a graph pattern.
• Allow engine to infer service invocation paths.

Very simple inference appears to model reasonable use cases.

Operation Rules

• Search input and output for an operation:

      <operation name="ItemSearch">
        <input message="aws:ItemSearchRequestMsg"/>
        <output message="aws:ItemSearchResponseMsg"/>
      </operation>
  

  for the annotations:

      <xs:element name="ItemSearch"
       spat:SPAT='?req aws:asin xpath("aws:ASIN")'>
          ...
            <xs:element name="ASIN" type="xs:string" minOccurs="0"/>
          ...
      </xs:element>

• Build rule from rule body (Input) and rule head (Output):

  ┌ op {http://webservices.amazon.com/AWSECommerceService/2004-11-10}ItemLookup: 
  │     fwrule ask(?req this:id XPath(., 91642dc) && 
  │                ?req this:asin XPath(., 919d638))
  │            assert(?req this:page _:<>:8.XPath(this:Items/this:Item/this:DetailPageURL, 91d37c8) && 
  │                   ?req this:reqId _:<>:9.XPath(., 9211c38) && 
  │                   ?req this:asin _:<>:10.XPath(aws:ASIN, 920b2b0) && 
  │                   ?req this:title _:<>:11.XPath(aws:Title, 9298a50))
  │               -->{<qname:{http://webservices.amazon.com/AWSECommerceService/2004-11-10}ItemLookup>}

Querying Rule Closure

The closure of the rules is now useful for answering user queries:

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

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

Studying Proof Chain

The proofs of these rules illustrate how to invoke the services:

Future Work

There's always more to play with...

• Clean up result iteration algorithm.
• Experiment with wider range of services.
• Implement in other inference engines.
• Many potential features to add...