Creating a Semantic Web with Linked Data

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Oct 21, 2013 (3 years and 9 months ago)

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Creating a Semantic Web with
Linked Data

Todd King

???

SPASE

FOAF

On the Road to Semantics

From Introducing Linked Data and the Semantic Web

http://www.linkeddatatools.com/semantic
-
web
-
basics

subject + predicate + object

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 SKOS

A 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 Integration)


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
>


As

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.