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From Wikipedia, the free encyclopedia

Linked Data is a sub-topic of the Semantic Web. The term Linked Data is used to describe a method of exposing, sharing, and connecting data via dereferenceable URIs on the Web.

Contents 1 Principles 2 Components 3 Linking Open Data Community Project 3.1 Dataset Instance and Class Relationships 4 Examples 4.1 Datasets 4.2 Use Case Demos 5 See also 6 External links 6.1 Further reading 6.2 Browsers 6.3 Presentations 6.4 Events

[edit] Principles

Tim Berners-Lee outlined four principles of Linked Data in his Design Issues: Linked Data note, paraphrased along the following lines:

• Use URIs to identify things that you expose to the Web as resources.
• Use HTTP URIs so that people can locate and look up (dereference) these things.
• Provide useful information about the resource when its URI is dereferenced.
• Include links to other, related URIs in the exposed data as a means of improving information discovery on the Web.

Tim Berners-Lee gave a presentation on Linked Data at the TED 2009 conference.

[edit] Components

• URIs (specifically, of the dereferenceable variety)
• HTTP
• Resource Description Framework (RDF)
• Serialization formats (RDFa, RDF/XML, N3, Turtle, and others)

[edit] Linking Open Data Community Project

The goal of the W3C Semantic Web Education and Outreach group's Linking Open Data community project is to extend the Web with a data commons by publishing various open datasets as RDF on the Web and by setting RDF links between data items from different data sources. As of October 2007, datasets consist of over two billion RDF triples, which are interlinked by over two million RDF links.

[edit] Dataset Instance and Class Relationships

Clickable diagrams that show the individual datasets and their relationships within LOD, as shown by the figures to the right, are:

• Instance relationships amongst datasets
• Class relationships amongst datasets

[edit] Examples

[edit] Datasets

• DBpedia - a dataset containing extracted data from Wikipedia; it contains about 2.18 million concepts described by 218 million triples, including abstracts in 11 different languages
• DBLP Bibliography - provides bibliographic information about scientific papers; it contains about 800,000 articles, 400,000 authors, and approx. 15 million triples
• GeoNames provides RDF descriptions of more than 6,500,000 geographical features worldwide.
• Revyu - a Review service consumes and publishes Linked Data, primarily from DBpedia.
• riese - serving statistical data about 500 million Europeans (the first linked dataset deployed with XHTML+RDFa)
• UMBEL - a lightweight reference structure of 20,000 subject concept classes and their relationships derived from OpenCyc, which can act as binding classes to external data; also has links to 1.5 million named entities from DBpedia and YAGO
• Sensorpedia - A scientific initiative at Oak Ridge National Laboratory using a RESTful web architecture to link to sensor data and related sensing systems.

[edit] Use Case Demos

• Data from Northwind SQL Schema as Linked Data
• Linked data for the discipline of numismatics

[edit] See also

• Entity-attribute-value model
• Open Data

[edit] External links

[edit] Further reading

• Linked Data Web architecture note by Tim Berners-Lee
• [1] Linked Data at the ESW Wiki
• Linking Open Data project wiki home page
• List of public Linked Data sources
• LinkedData.org
• Linked Data Community site
• Tutorial: How to publish Linked Data on the Web - Chris Bizer, Richard Cyganiak, Tom Heath
• White Paper: How to publish Linked Data on the Web using OpenLink Virtuoso
• Linked Data on the Web - Chris Bizer, Tom Heath, Kingsley Idehen, Tim Berners-Lee. In Proceedings WWW2008, Beijing, China.
• Interlinking Open Data on the Web - Chris Bizer, Tom Heath, Danny Ayers, Yves Raimond. In Proceedings Poster Track, ESWC2007, Innsbruck, Austria.

[edit] Browsers

• The Tabulator - Generic data browser and editor.
• OpenLink Data Explorer (ODE)
• Zitgist DataViewer - Linked Data Viewer
• Disco - Hyperdata Browser - A simple browser for navigating the Semantic Web.
• LENA - a Fresnel LEns based RDF/Linked Data NAvigator with SPARQL selector support.

[edit] Presentations

• Tim Berners Lee : The next Web of open, linked data at TED
• Linked Data: Principles and State of the Art - Chris Bizer, Tom Heath, Tim Berners-Lee at WWW2008
• The Linking Open Data Project - Bootstrapping the Web of Data - Tom Heath
• Creating, Deploying and Exploiting Linked Data - Keynote by Kingsley Idehen at Linked Data Planet, 2008
• Deploying Linked Data using OpenLink Virtuoso
• Native to a Web of Data - Tom Coates

[edit] Events

• Workshop on Linked Data on the Web (LDOW2008) at WWW2008
• LinkedData Planet 2008 conference in New York City

v • d • e Semantic Web Background World Wide Web  · Internet  · Databases  · Semantic networks  · Ontologies Sub-topics Linked Data  · Data Web  · Hyperdata  · Dereferenceable URIs  · Ontologies  · Rule bases  · Data Spaces Applications Semantic wiki · Semantic publishing · Semantic search · Semantic advertising · Semantic reasoner · Semantic matching · Semantic mapper · Semantic broker · Semantic analytics · Semantic service oriented architecture Related Topics Folksonomy  · Library 2.0 · Web 2.0  · Open Database Connectivity  · References  · Information architecture  · Knowledge management  · Collective intelligence  · Topic Maps  · Mindmapping  · Metadata · Geotagging · Description logic Standards Syntax & Supporting Technologies : RDF (Notation 3  · Turtle  · N-Triples)  · SPARQL  · URI  · HTTP  · XML Schemas, Ontologies & Rules : RDFS  · OWL  · Rule Interchange Format  · Semantic Web Rule Language Semantic Annotation : RDFa  · eRDF  · GRDDL  · Microformats Common Vocabularies : FOAF  · SIOC  · Dublin Core  · SKOS Others: Plain Old Semantic HTML People Tim Berners-Lee  · James Hendler  · Ora Lassila  · Nigel Shadbolt  · Wendy Hall Key Semantic Web Organizations W3C  · WSRI  · MIT  · OpenLink Software  · Talis Group  · ClearForest  · University of Southampton  · DERI