Creating a Semantic Web with Linked Data

Todd King

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On the Road to Semantics

From Introducing Linked Data and the Semantic Webhttp://www.linkeddatatools.com/semantic-web-basics

subject + predicate + objectsubject + predicate + object

Dublin Core

Dublin Core

What is "Linked Data"• RDF triples with shared vocabularies.• Basic RDF triple (statement):

subject+predicate+object

• Both "subject" and "object" are URI.Note: General RDF allows object to be literal values.

• General form in XML:<rdf:Description rdf:about="subject">    <predicate rdf:resource="object" /><rdf:Description>

RDF does not provide semantics.Well known (shared) vocabularies are

needed.

Defining a Collection as Linked Data

Using SPASE and SKOSA Collection called "Example" consisting of a NumericlaData

collection and a Document.

spase://vmo/NumericalData/ex1 skos:broader spase://vmo/Collection/example.

spase://vmo/Document/ex1 skos:broader spase://vmo/Collection/example.

The Big Question Are associations best expressed external to

the resources or internal?

External: Linked Data Internal: Declared associations

(i.e. Association in SPASE)

In either case a focal point for associations is needed.

Background Information

Well-Known Vocabularies • Friend-of-a-Friend (FOAF), vocabulary for describing people.• Dublin Core (DC) defines general metadata attributes. See

also their new domains and ranges draft.• Semantically-Interlinked Online Communities (SIOC),

vocabulary for representing online communities.• Description of a Project (DOAP), vocabulary for describing

projects.• Simple Knowledge Organization System (SKOS),

vocabulary for representing taxonomies and loosely structured knowledge.

• Music Ontology provides terms for describing artists, albums and tracks.

• Review Vocabulary, vocabulary for representing reviews.• Creative Commons (CC), vocabulary for describing license

terms.

Science Vocabularies SESDI (Semantically-Enabled Science Data Integra

tion) SWEET (Semantic Web for Earth and

Environmental Terminology) SPASE (Space Physics Archive Search and Extract) GEON (Geosciences Network) VSTO (Virtual Solar-Terrestrial Observatory) Noesis (Earth and Atmospheric Science Smart

Search) MMI (Marine Metadata Initiative)

VINE (Vocabulary Integration Environment Tool) Hydroseek (ontology-aided search)

RDF Statements

SPASE RDF<Spase>

<Version>2.0.1</Version>

<Person>

<ResourceID>spase://SMWG/Person/Todd.A.King</ResourceID>

<ReleaseDate>2010-02-04T12:34:56.789</ReleaseDate>

<PersonName>Todd A. King</PersonName>

<OrganizationName>

Institute of Geophysics and Planetary Physics, University of California, Los Angeles

</OrganizationName>

<Address>

Institute of Geophysics and Planetary Physics, University of California Los Angeles, Box 951567, Los Angeles, CA 90095-1567

</Address>

<Email>tking@igpp.ucla.edu</Email>

<PhoneNumber>+1 310 206 7201</PhoneNumber>

</Person>

</Spase>

<?xml version="1.0" encoding="UTF-8"?>

 

<rdf:RDF

xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"

xmlns:spase="http://www.spase-group.org/rdf#">

    <rdf:Description rdf:about="spase://SMWG/Person/Todd.A.King">

        <spase:PersonName>Todd A. King</spase:PersonName>

        <spase:OrganizationName>

Institute of Geophysics and Planetary Physics, University of California, Los Angeles

</spase:OrganizationName>

        <spase:Address> Institute of Geophysics and Planetary Physics, University of California Los Angeles, Box 951567, Los Angeles, CA 90095-1567

</spase:Address>

<spase:Email>tking@igpp.ucla.edu</spase:Email>

<spase:PhoneNumber>+1 310 206 7201</spase:PhoneNumber>

    </rdf:Description>

 

</rdf:RDF>

AsAs

Note: Slightly redacted and not using preferred namespaces in RDF version.

Anything in XML can represented in RDF

Why Semantics?• Knowledge Integration– It allows branching across domains of knowledge.– Allows independent operation/evolution for each

domain.

Semantic Modeling consists of:• Vocabulary - A collection of terms given a well-

defined meaning that is consistent across contexts.• Ontology - Allows you to define contextual

relationships behind a defined vocabulary. Definitions from Introducing Linked Data and the Semantic Web

Semantic Web The Semantic Web Is a paradigm shift from the relational or

hierarchical means of modeling data to a graph model.