Linked Data PrinciplesOregon Digital Linked Data Workshop, Eugene, OregonNovember 25, 2013

Tom Johnson thomas.johnson@oregonstate.edu

4 Principles

1. Use URIs as names for things

2. Use HTTP URIs so that people can look up those names.

3. When someone looks up a URI, provide useful information, using the standards (RDF*, SPARQL)

4. Include links to other URIs. so that they can discover more things.

Subject, Predicate, Object

<http://example.org/object1>

<http://example.org/collection1>

“Example Title”

Subject Predicate Object

<http://example.org/object1>

<http://purl.org/dcterms/isPartOf>

<http://purl.org/dcterms/title>

What is a Graph?

Data Model Example

Serializing

N-Triples:<http://example.org/1> <http://purl.org/dcterms/title> “Comet in Moominland”@en .

<http://example.org/1> <http://purl.org/dcterms/title> “Mumintrollet på kometjakt”@sv .

<http://example.org/1> <http://purl.org/dcterms/creator> <http://example.

org/person/tjannson> .

<http://example.org/1> <http://purl.org/dcterms/subject> <http://id.loc.

gov/authorities/subjects/sh2001004219> .

<http://id.loc.gov/authorities/subjects/sh2001004219> <http://www.w3.

org/2004/02/skos/core#prefLabel> "Moomins (Fictitious characters)"@en .

<http://example.org/person/tjannson> <http://xmlns.com/foaf/0.1/name> “Tove Jansson” .

Serializing

Turtle

ex:1 dc:title “Comet in Moominland”@en,

“Mumintrollet på kometjakt”@sv ;

dc:creator ex:person/tjansson ;

dc:subject lcsh:sh2001004219 .

ex:person/tjansson foaf:name “Tove Jansson” .

lcsh:sh2001004219 skos:prefLabel "Moomins (Fictitious

characters)"@en .

Practical Semantics

➢ Hierarchical Metadata Terms⇒ relationships between vocabularies⇒ e.g. mrel:photographer < dc:contributor

➢ Domain and Range Statements⇒ Limit vocabulary application for data quality and

interoperability

➢ Objects in one statement can be subjects in others.

Global Scale

➢ Statement-centric

➢ Model is “Open World”⇒ Data we don’t have is assumed to be unknown

locally, not globally.

➢ Outside data is valued➢ Linking is web scale

Resources

➢ Linked Open Vocabularies (vocabulary search engine) http://lov.okfn.org/dataset/lov/

➢ W3C Library Linked Data Incubator Group Reports http://www.w3.org/2005/Incubator/lld/

➢ Open Metadata Registry (hosts RDA vocabularies) http://metadataregistry.org/

Questions/Discussion

Challenges from readings?Questions about why & how?Observations?