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Bert Bos | La plateforme Web

Linked Data

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Bert Bos (W3C) <bert@w3.org>

W3C Days 2012
Rabat, Maroc
8 novembre 2012

Based on original slides by Phil Archer <phila@w3.org>

Linked Data

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Linked Data Basics

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Statue of Einstein outside the Science Museum in Canberra

Here is a picture.

Linked Data Basics

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Statue of Einstein outside the Science Museum in Canberra

Here is a picture.

Of Albert Einstein

Linked Data Basics

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Statue of Einstein outside the Science Museum in Canberra

Here is a picture

Of Albert Einstein

And his famous equation: e=mc2

Linked Data Basics

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Statue of Einstein outside the Science Museum in Canberra

Here is a picture

Of Albert Einstein

And his famous equation: e=mc2

Actually, it's a picture of a sculpture of Albert Einstein

Linked Data Basics

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Statue of Einstein outside the Science Museum in Canberra

Here is a picture

Of Albert Einstein

And his famous equation: e=mc2

Actually, it's a picture of a sculpture of Albert Einstein

Find out more...

Google Bing Yahoo!

Linked Data Basics

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Wouldn't it be great if your computer could do all that looking up for you?

Linked Data Basics

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Status of Einstein outside the Science Museum in Canberra

http://www.w3.org/2012/Talks/0710_phila_bcs/einstein.jpg is a http://en.wikipedia.org/wiki/Image.

Of http://en.wikipedia.org/wiki/Albert_Einstein

And his famous equation: http://en.wikipedia.org/wiki/Mass-energy_equivalence

Actually, it's a http://en.wikipedia.org/wiki/Image of a http://en.wikipedia.org/wiki/Sculpture of http://en.wikipedia.org/wiki/Albert_einstein

Einstein's statue in a graph

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Each sentence about the photo of the statue of Einstein is an edge in a graph.

The same in another graph

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Another set of information about the same sculpture says that the sculpture is located outside the Questacon Science Museum.

Einstein's statue linked!

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The two information graphs both contain the sculpture as a node: that means they can be linked and form a single larger graph.

Things and Documents About Them

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Previous data model is an over-simplification.

HTTP GET on http://en.wikipedia.org/wiki/Albert_Einstein returns: 

200 OK
Cache-Control: private, s-maxage=0, max-age=0, must-revalidate
Connection: close
Date: Sat, 07 Jul 2012 09:10:07 GMT
Server: Apache
Vary: Accept-Encoding,Cookie
Content-Language: en
Content-Length: 351336
Content-Type: text/html; charset=UTF-8
Expires: Thu, 01 Jan 1970 00:00:00 GMT
Last-Modified: Fri, 06 Jul 2012 15:21:23 GMT

Things and Documents About Them

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DBpedia (logo) Hence DBpedia: For each Wikipedia entry, creates two URIs:

URIs resolved through HTTP content negotiation and 303 redirection.

Source of long-running debate (“httpRange-14”), that we will not get into today. See e.g., Jeni Tennison's blog post

Einstein's statue (2nd version)

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The previous graph, but with dbpedia URLs instead of wikipedia ones.

http://dbpedia.org/resource/Albert_Einstein (RDF/XML)

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<rdf:Description rdf:about="http://dbpedia.org/resource/Le%C3%B3_Szil%C3%A1rd">
    <dbpedia-owl:academicAdvisor rdf:resource="http://dbpedia.org/resource/Albert_Einstein" />
    <dbpprop:academicAdvisors rdf:resource="http://dbpedia.org/resource/Albert_Einstein" />
  </rdf:Description>
  <rdf:Description rdf:about="http://dbpedia.org/resource/Stephen_Hawking">
    <dbpedia-owl:influencedBy rdf:resource="http://dbpedia.org/resource/Albert_Einstein" />
    <dbpprop:influences rdf:resource="http://dbpedia.org/resource/Albert_Einstein" />
  </rdf:Description>
  <rdf:Description rdf:about="http://dbpedia.org/resource/Nathan_Rosen">
    <dbpedia-owl:academicAdvisor rdf:resource="http://dbpedia.org/resource/Albert_Einstein" />
    <dbpprop:academicAdvisors rdf:resource="http://dbpedia.org/resource/Albert_Einstein" />
  </rdf:Description>
  <rdf:Description rdf:about="http://dbpedia.org/resource/Einstein_%28disambiguation%29">
    <dbpedia-owl:wikiPageDisambiguates rdf:resource="http://dbpedia.org/resource/Albert_Einstein" />
  </rdf:Description>

If you do an HTTP request on the DBpedia URL for Albert Einstein, asking for the RDF version (with the HTTP Accept header), you'll get this RDF document.

http://dbpedia.org/resource/Albert_Einstein (Turtle)

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dbpedia:Albert_Einstein	rdfs:comment "Albert Einstein was a German-born theoretical 
physicist who developed the theory of general relativity, effecting a revolution 
in physics. For this achievement, Einstein is often regarded as the father of 
modern physics and one of the most prolific intellects in human history. He received 
the 1921 Nobel Prize in Physics \"for his services to theoretical physics, 
and especially for his discovery of the law of the photoelectric effect\"."@en ,

"Albert Einstein est un physicien th\u00E9oricien d'origine juive qui fut 
successivement allemand, puis apatride (1896), suisse (1901), et enfin helv\u00E9tico-am\u00E9ricain 
(1940). Il publie sa th\u00E9orie de la relativit\u00E9 restreinte en 1905, et 
une th\u00E9orie de la gravitation dite relativit\u00E9 g\u00E9n\u00E9rale en 1915. Il 
contribue largement au d\u00E9veloppement de la m\u00E9canique quantique et de la 
cosmologie, et re\u00E7oit le prix Nobel de physique de 1921 pour son explication 
de l\u2019effet photo\u00E9lectrique."@fr .

This is the same document, but in Turtle (which expresses RDF in a non-XML format, sometimes easier to read).

http://dbpedia.org/resource/Albert_Einstein (HTML)

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303 See Other
Connection: close
Date: Sat, 07 Jul 2012 10:03:27 GMT
Accept-Ranges: bytes
Location: http://dbpedia.org/page/Albert_Einstein
Server: Virtuoso/06.04.3132 (Linux) x86_64-generic-linux-glibc25-64  VDB
Content-Length: 0
…

And if you retrieve the same DBpedia URL asking for an HTML version, you'll get the above, which is a redirect to the Wikipedia article. (The 303 is normally used by a server to indicate to a client that a POST request should be replaced by a GET request. As a convention, semantic Web people use it to indicate that the redirect is to a description of the requested object, rather than the object itself.

http://dbpedia.org/page/Albert_Einstein

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This frame just contains the DBpedia page at http://dbpedia.org/page/Albert_Einstein

DBpedia graph

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(backup)

More…

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Open Government Data

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Public sector holds a lot of data:

Open Government Data

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Most Open Government Data released as CSV (source)

Most apps are Web based and visualise a single static dataset.

± 90% of the apps surveyed combine OGD with maps, mainly Google Maps and Open Street Map.

Open Government Data

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Many challenges remain:

Lichfield My Area

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screenshot of Lichfield My Area service

The Lichfield District Council in the UK gives access to data linked to geographic locations.

Lichfield My Area

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screenshot of Lichfield My Area service

Bathing Water Data Explorer

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Bathing Water Quality Explorer homepage

The England and Wales government's collected data about water quality at beaches around the coast.

Bathing Water Data Explorer

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Bathing Water Quality Explorer for Bowleaze Cove

Open Government Data Around the World

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Open Government Data Around the World

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Map of government data sites around the world

The 5 Stars of Linked Open Data

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5 Star Linked data Mug

★ Available on the web (whatever format) but with an open licence, to be Open Data

★★ machine-readable structured data (e.g. excel instead of image scan of a table)

★★★ as (2) plus non-proprietary format (e.g. CSV instead of excel)

The 5 Stars of Linked Open Data

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5 Star Linked data Mug

★★★★ All the above plus, Use open standards from W3C (RDF and SPARQL) to identify things, so that people can point at your stuff

★★★★★ All the above, plus: Link your data to other people’s data to provide context

Originally developed by Tim Berners-Lee

The end

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www.w3.org/Talks/2012/1108-LOD-Rabat

W3C

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Join W3C

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or contact: Bernard Gidon <bgidon@w3.org>

Bert Bos <bert@w3.org>
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