bringing rdf to digital contents towards the semantic web

Bringing RDF to Digital ContentsTowards the Semantic Web

Ching-Long YehDepartment of Computer Science and Engineering

Tatung [email protected] (msn)

http://www.cse.ttu.edu.tw/chingyeh

Bringing RDF to Digital Contents 2

Web Technology Overview

• WWW (human-to-machine interactions)– Infrastructure

• HTML, HTTP, URI, browsers– Services

• Search engine and directory navigation

• WWW + XML (human-to-machine and machine-to-machine interactions)– Web Services (UDDI, WSDL, SOAP)

• SOA (Registry, provider, requester)• Automatic service processing

– ebXML• SOA for business automation

– discovery, implementation, run-time phases• Business process + message service

– Semantic Web• Meaning processing automation• WWW + metadata layer (OWL+RDF)• Services automation (WWW+OWL-S/RDF)• Semantic Grid


Semantic Web

• The Semantic Web is a vision:

the idea of having data on the web defined and linked in a way that it can be used by machines not just for display purposes, but for automation, integration and reuse of data across various applications


Semantic Web

• The Semantic Web = a Web with a meaning.

"If HTML and the Web made all the online documents look like one huge book, RDF, schema, and inference languages will make all the data in the world look like one huge database“

Tim Berners-Lee, Weaving the Web, 1999


Introduction from W3C SW Activity

• The Semantic Web is a web of data.

• The Semantic Web is about two things. – Common formats for interchange of data,

• On the original Web we only had interchange of documents.

– Language for recording how the data relates to real world objects• That allows a person, or a machine, to start off in one database, and then

move through an unending set of databases which are connected not by wires but by being about the same thing.


The Semantic Web Architecture

(http://www.w3.org/2001/Talks/0228-tbl/slide5-0.html)

Tim Berners-Lee:“Axioms, Architecture and Aspirations”W3C all-working group plenary Meeting28 February 2001

URI Unicode

XML Namespaces

XML Schema

Sig./Ency.

RDF M&S

RDF Schema

Ontology (OWL)

Rules (SWRL)

Logic (FOL)

Proof

Trust

I. Horrocks, et al. Semantic web architecture: Stack or two towers? In F. Fages and S. Soliman, (eds.), Principles and Practice of Semantic Web Reasoning (PPSWR 2005), number 3703 in LNCS, pages 37-41. SV, 2005. http://www.cs.man.ac.uk/~horrocks/Publications/download/2005/HPPH05.pdf

RDF and Schema Languages


RDF M&S

• RDF (Resource Description Framework)

• RDF consists of two parts– RDF Model (a set of triples)

– RDF Syntax (different XML serialization syntaxes)

• RDF Schema for definition of Vocabularies (simple Ontologies) for RDF (and in RDF)


RDF Data Model

• Resources– A resource is a thing you talk about (can reference)

– Resources have URI’s

• Properties – slots, define relationships to other resources or atomic values

• Statements– “Resource has Property with Value”

– (Values can be resources or atomic XML data)

• Similar to Frame Systems


A Simple Example

• Statement– “Ora Lassila is the creator of the resource

http://www.w3.org/Home/Lassila”

• Structure– Resource (subject) http://www.w3.org/Home/Lassila– Property (predicate) http://www.schema.org/#Creator– Value (object) "Ora Lassila”

• Directed graph

http://www.w3.org/Home/Lassilas:Creator Ora Lassila


EmailName

s:Creator

http://www.w3.org/Home/Lassila

Another Example

• To add properties to Creator, point through an intermediate Resource.

Person://fi/654645635

Ora Lassila [email protected]


Example: Bag

• The students incourse 6.001 are Amy, Tim,John, Mary,and Sue Rdf:Bag

/Students/Amy

/Students/Tim

/Students/John

/Students/Mary

/Students/Sue

bagid1

/courses/6.001

students

rdf:type

rdf:_1

rdf:_2

rdf:_3

rdf:_4

rdf:_5


rdf:_1

rdf:_2

rdf:_3

rdf:typesource

ftp.eu.net

ftp.cs.purdue.edu

ftp.x.org

Example: Alternative

• The source code for X11 may be found at ftp.x.org, ftp.cs.purdue.edu, or ftp.eu.net

altid

rdf:Althttp://x.org/package/X11


<?xml version="1.0"?><rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:contact="http://www.w3.org/2000/10/swap/pim/contact#">

<contact:Person rdf:about="http://www.w3.org/People/EM/contact#me"> <contact:fullName>Eric Miller</contact:fullName> <contact:mailbox rdf:resource="mailto:[email protected]"/> <contact:personalTitle>Dr.</contact:personalTitle> </contact:Person>

</rdf:RDF>


OWLW3C Web Ontology Language

• OWL provides three increasingly expressive sublanguages: OWL Lite, OWL DL, and OWL Full.


OWLW3C Web Ontology Language

OWL Lite language constructs

RDF Schema Features: Class rdf:Property rdfs:subClassOf rdfs:subPropertyOf rdfs:domain rdfs:range Individual

(In)Equality: equivalentClass equivalentProperty sameAs differentFrom allDifferent

Property Characteristics: inverseOf TransitiveProperty SymmetricProperty FunctionalProperty InverseFunctionalProperty

Property Type Restrictions: allValuesFrom someValuesFrom

Restricted Cardinality: minCardinality (only 0 or 1) maxCardinality (only 0 or 1) cardinality (only 0 or 1)

Header Information: ontology imports

Semantic Web System Architectures


Typical System Architecture


Layered Architecture


SesameA generic Architecture for Storing and Querying RDF and RDF Schema


Adding RDF Metadata to PW

Picture Write(PC)

Picture Write(browser)

Picture Write(browser)

picturepicture

picturepicturepicture

pictureRelational DB

Conversion ProgramRDF OWL

(RDF store)

API

Semantic Services

Picture WriteNew version

AdministrationServices

TO BE (Web 2.0) AS IS Contents and services on

the WWWContents and services on

the Semantic Web


RDF/OWL Representation of WordNet

• WordNet [Fellbaum, 1998] is a heavily-used lexical resource in natural-language processing and information retrieval.

• More recently, it has also been adopted in Semantic Web research community.

• It is used mainly for annotation and retrieval in different domains such as cultural heritage [Hollink et al., 2003], product catalogs [Guarino et al., 1999] and photo metadata [Brickley, 2002].

• It is also used to ground other vocabularies such as the FOAF schema [Brickley and Miller, 2005], as background knowledge in ontology alignment tools and other applications (see http://esw.w3.org/mt/esw/archives/cat_applications_and_demos.html for a list).

• Currently there exist several conversions of WordNet to RDF(S) or OWL.

http://www.w3.org/2001/sw/BestPractices/WNET/wn-conversion.html#fellbaum98

http://www.w3.org/2001/sw/BestPractices/WNET/wn-conversion.html#fellbaum98

http://www.w3.org/2001/sw/BestPractices/WNET/wn-conversion.html#hollink03

http://www.w3.org/2001/sw/BestPractices/WNET/wn-conversion.html#hollink03

http://www.w3.org/2001/sw/BestPractices/WNET/wn-conversion.html#guarino99

http://www.w3.org/2001/sw/BestPractices/WNET/wn-conversion.html#guarino99

http://www.w3.org/2001/sw/BestPractices/WNET/wn-conversion.html#brickley02




http://esw.w3.org/mt/esw/archives/cat_applications_and_demos.html


Class Hierarchy of the WordNet Schema

Synset AdjectiveSynset

AdjectiveSatelliteSynset AdverbSynset NounSynset VerbSynset

WordSense AdjectiveWordSense

AdjectiveSatelliteWordSense AdverbWordSense NounWordSense VerbWordSense

Word Collocation


Combining the Metadata of Digital Content with WordNet

The metadata database


Use of RDF Metadata (1)

• Integrating existing programs into the Semantic Web– Newer versions of Picture Write

– Newer versions of PMLS



• Effective management of digital contents– Defining standard vocabularies (ontology)

– Classifications of digital content

– Conceptual search and semantic navigation

– Web services



• Making digital contents more beneficial– Pictures bundled with RDF metadata can be further processed by

clients.

– We sell digital content not only for presentation but also for meaning processing.

• We sell not only physical files of pictures but also their metadata.

– New business model (?)



• Automatic generation of pictures sequence to extend the scope of pictures from word level to phrase or even sentence level– Natural language processing technology is employed to enhance the

current word-level matching method.

– The RDF metadata can be seen as the knowledge base to support advanced processing using the natural language processing technique.

Thank You

bringing rdf to digital contents towards the semantic web

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