Transcript Semantic Web Service Composition

OWL Annotation Tool
Supervisor: Mike Rosner
Co-Supervisor: Charlie Abela
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Overview
 Implement an annotating tool which can
be used to add OWL descriptions to the
CSAI department’s web pages thus
making their content accessible to
semantically enabled software agents.
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The Semantic Web
• Focus on machine consumption:
"The Semantic Web is an extension of the current web in
which information is given well-defined meaning,
better enabling computers and people to work in
cooperation." – Tim Berners-Lee, Hendler and Lassila,
The Semantic Web, Scientific American, 2001
• Whereas the Web has made people smarter, the
SW will make machines smarter.
• The current Web stores things whereas the SW
enables agents which do things.
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TBL’s semantic web vision
“The Semantic Web
will globalize KR,
just as the WWW
globalize hypertext”
-- Tim Berners-Lee
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Why HTML is not enough
• Consider
a
web
document
describing
information related to a
particular lecture.
• A software agent that
stumbles over this page
while
performing
a
search,
cannot
understand any of the
information on this page
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What a web page looks like to a
machine…
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One solution….
We could tell the
machine what the
different parts of the
text represent
title
speaker
time
location
abstract
biosketch
host
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Make use of XML
<title>
<speaker>
<time>
<location>
</title>
</speaker>
</time>
XML fans propose
creating an XML tag set
to use for each
application.
</location>
For talks, we can
choose <title>,
<speaker>, etc.
<abstract>
</abstract>
<biosketch>
</biosketch>
<host>
</host>
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XML  Machine accessible meaning
<title>
<speaker>
<time>
<location>
<abstract>
<biosketch>
<host>
</title>
</speaker>
</time>
</location>
</abstract>
</host>
But, to your
machine, the
tags still look like
this….
The tag names
carry no meaning.
XML DTDs and
Schemas have
little or no
semantics.
</biosketch>
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XML Schemas provide a
simple mechanism to
define shared
vocabularies.
XML Schema helps
XML Schema file
<?xml version="1.0" encoding="utf-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="book">
<xs:complexType>
<xs:sequence>
<xs:element name="title" type="xs:string"/>
<xs:element name="author" type="xs:string"/>
<xs:element name="character" minOccurs="0" maxOccurs="unbounded">
<xs:complexType>
<xs:sequence>
<xs:element name="name" type="xs:string"/>
<xs:element name="friend-of" type="xs:string" minOccurs="0"
maxOccurs="unbounded"/>
<xs:element name="since" type="xs:date"/>
<xs:element name="qualification" type="xs:string"/>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
<xs:attribute name="isbn" type="xs:string"/>
</xs:complexType>
</xs:element>
</xs:schema>
<title>
<speaker>
<time>
<location>
<abstract>
<biosketch>
<host>
</title>
</speaker>
</time>
</location>
</abstract>
</biosketch>
</host>
<title>
<speaker>
<time>
<location>
<abstract>
<biosketch>
<host>
</title>
</speaker>
</time>
</location>
</abstract>
</biosketch>
</host> 10
after Frank van Harmelen and Jim Hendler
XML & XML Schemas are still not
enough
• There may exist many schemas that
define the same information
• And there is no way to relate these
schemas together, either manually or
automatically -- XML Schema is very
weak on semantics
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The Semantic Web Solution
• Make use of more expressive XML-based
languages
– Resource Description Language (RDF)
– Darpa Agent Markup Language (DAML)
– Web Ontology Language (OWL)
• Make use of concept definition repositories
– Ontologies
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RDF
• RDF is based on the idea of identifying things
using Web identifiers (called Uniform
Resource Identifiers, or URIs),
• Resources are described in terms of simple
properties and property values.
• This enables RDF to represent simple
statements about resources as a graph of
nodes and arcs representing the resources,
and their properties and values
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An Example
A Simple Fact
http://www.example.org/index.html has a
creation-date whose value is August 16, 1999
RDF/XML representation
<?xml version="1.0"?>
<rdf:RDF xmlns:rdf=http://www.w3.org/1999/02/22-rdf-syntaxns#
xmlns:exterms="http://www.example.org/terms/">
<rdf:Description
rdf:about="http://www.example.org/index.html">
<exterms:creation-date>August 16,
1999</exterms:creation-date>
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</rdf:Description>
Example (cont)
Directed Graph representation
http://www.example.org/index.html
Subject
Predicate
http://www.example.org/terms/creation-date
August 16, 1999
Object
Statement is described by a Triple:
(Subject, Predicate, Object)
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Ontologies
•
•
An ontology defines the terms used to describe and represent
an area of knowledge.
Ontologies are used by people, databases, and applications that
need to share domain information (a domain is just a specific
subject area or area of knowledge, like medicine, tool
manufacturing, real estate, automobile repair, financial
management, etc.). Ontologies include computer-usable definitions
of basic concepts in the domain and the relationships among them
...
They encode knowledge in a domain and also knowledge that
spans domains.
In this way, they make that knowledge reusable.
Working Draft, Web Ontology Working Group.
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Annotating HTML
• Annotating tools allow inserting and
maintaining ontology-based markups in Web
pages
• The objective of these tools is to alleviate the
burden
of
including
ontology-based
annotations manually into Web pages
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Web Page Annotation:
An Example
<html>
<head> <!--Start of Commented RDF -->
<!-<rdf:RDF
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:daml="http://www.daml.org/2001/03/daml+oil#"
xmlns:"http://www.cse.dmu.ac.uk/~monika/Pages/Ontology.daml#">
<PhDStudent rdf:ID="Monika">
<has_affiliation rdf:resource=
"#http://www.cse.dmu.ac.uk/monika/Ontology.daml#DMU"/>
<name>Monika Solanki</name>
<address>Hawthorn building, H00.18 </address>
<country>U.K.</country>
......
......
......
</PhDStudent>
</rdf:RDF>
--><!-- End of Commented RDF -->
</head>
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Annotation Tool:
Proposed Architecture
Ontology
Editor
Web
Browser
Annotated
Web Pages
Ontology
Annotator
Tool
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Main Issues
• Ontology Editor: any ready made tool
• Ontology Building: related to CSAI department
– Information should refer to departmental lecturing staff, the
courses they teach, research, publications etc
• Web Browser: permits manipulation (such as
highlighting) of rendered html
• Annotator: Maps text chosen from Web page to
concepts defined in the ontology
– Concepts refer to defined classes, properties and instances for a
particular domain
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Literature
• Towards Annotation using DAML+OIL, Bechnofer, Goble
• RDF Primer: http://www.w3.org/TR/2004/REC-rdf-primer-20040210/
• OWL Tutorial:
http://www.cs.man.ac.uk/~horrocks/ISWC2003/Tutorial/
• Tutorial on Ontology creation:
http://www.ksl.stanford.edu/people/dlm/papers/ontology101/ontology101-noy-mcguinness.html
• Ontomat: http://annotation.semanticweb.org/tools/ontomat
• FOAF (friends of a friend ontology), http://xmlns.com/foaf/0.1/
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