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Deutsches Kulturerbe auf dem Weg in die EuropeanaOctober 5th, 2010, Berlin, Germany
Linked DataLinked DataE t di th W b ith Extending the Web with a global public Dataspace
Prof. Dr. Christian Bizer Freie Universität Berlin
Christian Bizer: Europeana Conference (05/10/2010)
Outline
1. Foundations of Linked Data What is the vision and goal?
2. The Web of Linked Data What data is out there?
3. Linked Data Applications What is being done with the data?
Christian Bizer: Europeana Conference (05/10/2010)
Linked Data Principles
Set of best practices for publishingSet of best practices for publishing structured data on the Web in accordance with the general architecture of the Web.
1 Use URIs as names for things1. 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 RDFinformation.
4. Include RDF statements that link to other URIs so that they can discover related things.
Tim Berners-Lee, http://www.w3.org/DesignIssues/LinkedData.html, 2006
Christian Bizer: Europeana Conference (05/10/2010)
Architecture of the classic Web
Single global information spaceWeb
BrowsersSearch Engines
Single global information space
S ll t f i l t d dSmall set of simple standards1. HTML as document format2 HTTP URL
HTTP
HTML HTMLHTML
2. HTTP URLs as globally unique IDs retrieval mechanism
hyper-links
retrieval mechanism
3. Hyperlinks to connect everything
B CA B CA
Christian Bizer: Europeana Conference (05/10/2010)
Web 2.0 APIs and Mashups
No single global dataspaceMashup
Up
No single global dataspace
Sh t iShortcomings
1. APIs have proprietary interfaces
WebAPI
2. No hyperlinks between data items within different APIs
3 M h b d
WebAPI
WebAPI
WebAPI
3. Mashups are based on a fixed set of data sources
A B C DA B C D
Christian Bizer: Europeana Conference (05/10/2010)
Web APIs slice the Web into Walled Gardens
Christian Bizer: Europeana Conference (05/10/2010)Image: Bob Jagensdorf, http://flickr.com/photos/darwinbell/, CC-BY
Linked Data
Extend the Web with a single global dataspace1. by using RDF to publish structured data on the Web2. by setting links between data items within different
data sources.
RDF RDF RDF RDF RDFRDF
RDF
RDF
RDF
RDF
RDF RDF
RDF
RDF
RDF
RDFlink
RDFlinks
RDFlinks
RDFlinks
B CA D E
Christian Bizer: Europeana Conference (05/10/2010)
The RDF Data Model
rdf:type
f f
foaf:Personrdf:type
pd:cygri
Richard Cyganiakfoaf:name
foaf:based neardbpedia:Berlin
foaf:based_near
Flexible graph-based data model.
Christian Bizer: Europeana Conference (05/10/2010)
Data items are identified with HTTP URIs
rdf:typepd:cygri
f f
foaf:Personrdf:type
Richard Cyganiakfoaf:name
foaf:based neardbpedia:Berlin
foaf:based_near
HTTP URIs take the role of global primary keys.
d i htt // i h d i k d /f f df# ipd:cygri = http://richard.cyganiak.de/foaf.rdf#cygridbpedia:Berlin = http://dbpedia.org/resource/Berlin
Christian Bizer: Europeana Conference (05/10/2010)
Resolving URIs over the Web
rdf:type
3 405 259f f
foaf:Personrdf:type
pd:cygri
3.405.259dp:populationRichard Cyganiak
foaf:name
foaf:based near
skos:subject
dbpedia:Berlinfoaf:based_near
d Citi i G
skos:subject
dp:Cities_in_Germany
The HTTP protocol brings together identification and retrie al
Christian Bizer: Europeana Conference (05/10/2010)
retrieval.
Following RDF links deeper into the Web
rdf:type
3 405 259f f
foaf:Personrdf:type
pd:cygri
3.405.259dp:populationRichard Cyganiak
foaf:name
foaf:based near
skos:subject
dbpedia:Berlinfoaf:based_near
d Citi i G
skos:subject
db di H bskos:subject
dp:Cities_in_Germanydbpedia:Hamburg
dbpedia:Muenchen skos:subject
Christian Bizer: Europeana Conference (05/10/2010)
The Disco – Hyperdata Browser
Christian Bizer: Europeana Conference (05/10/2010)
Christian Bizer: Europeana Conference (05/10/2010)
Properties of the Web of Linked Data
Global, distributed dataspace build on a simple set of standards RDF, URIs, HTTP
Entities are connected by links creating a single global data graph that spans data sources and
enables the discovery of new data sources
Provides for data-coexistence Everyone can publish data to the Web of Linked Data Everyone can publish data to the Web of Linked Data
Everyone can express their personal view on things
Everybody can use the vocabularies/schema that they like Everybody can use the vocabularies/schema that they like
Christian Bizer: Europeana Conference (05/10/2010)
2. Linked Data Deployment on the Web
Is this real?
RDF RDF RDF RDF RDFRDF
RDF
RDF
RDF
RDF
RDF RDF
RDF
RDF
RDF
RDFlink
RDFlinks
RDFlinks
RDFlinks
B CA D E
Christian Bizer: Europeana Conference (05/10/2010)
W3C Linking Open Data Project
Grassroots community effort toy publish existing open license datasets as Linked Data on the Web interlink things between different data sources
Christian Bizer: Europeana Conference (05/10/2010)
LOD Datasets on the Web: May 2007
Over 500 million RDF triples
Christian Bizer: Europeana Conference (05/10/2010)
p Around 120,000 RDF links between data sources
LOD Datasets on the Web: September 2008
Christian Bizer: Europeana Conference (05/10/2010)
LOD Datasets on the Web: July 2009
Christian Bizer: Europeana Conference (05/10/2010)
Over 13.1 billion RDF triples Over 142 million RDF links between data sources
LOD Datasets on the Web: September 2010
Christian Bizer: Europeana Conference (05/10/2010)
Over 25 billion RDF triples Over 395 million RDF links between data sources
Christian Bizer: Europeana Conference (05/10/2010)
Christian Bizer: Europeana Conference (05/10/2010)
Uptake in Life Sciences
W3C Linking Open Drug Data Effort
Bio2RDF Project
Allen Brain Atlas
Goal: Use single architecture to integrate internal and external data
Christian Bizer: Europeana Conference (05/10/2010)
and external data.
Uptake in the Media Industry
Publish data as RDF/XML or RDFa
Goal: Drive traffic to websites via Goal: Drive traffic to websites via search engines, other sites
Christian Bizer: Europeana Conference (05/10/2010)
Uptake in the Libraries Community
Institutions publishing Linked Data Library of Congress (subject headings)
Deutsche Nationalbibliothek (PND dataset and subject headings)
Deutschen Zentralbibliothek für Wirtschaftswissenschaften (subject headings)
Swedisch National Library (Libris - catalog)
Hungarian National Library (OPAC and Digital Library)
W3C Library Linked Data Incubator Group
Open Archives ORE StandardOpen Archives ORE Standard
Goals:Goals: Integrate library catalogs on global scale.
Interlink content between repositories (locations people citations )
Christian Bizer: Europeana Conference (05/10/2010)
Interlink content between repositories (locations, people, citations, …)
3. Linked Data Applications
What can I do with this?
Search Engines
Linked DataMashups
Linked DataBrowsers EnginesMashupsBrowsers
Thing Thing Thing Thing ThingThing
Thing
Thing
Thing
Thing
Thing Thing
Thing
Thing
Thing
typedlinks
typedlinks
typedlinks
typedlinks
B CA D E
Christian Bizer: Europeana Conference (05/10/2010)
Linked Data Browsers
P id f i ti b t d tProvide for navigating between data sources and for exploring the dataspace.
Tabulator Browser (MIT, USA)
Marbles (FU Berlin, DE)
OpenLink RDF Browser (OpenLink, UK)p ( p )
Zitgist RDF Browser (Zitgist, USA)
Di H d t B (FU B li DE)Disco Hyperdata Browser (FU Berlin, DE)
Fenfire (DERI, Irland)
Christian Bizer: Europeana Conference (05/10/2010)
Christian Bizer: Europeana Conference (05/10/2010)
Web of Data Search Engines
C l th d t d id b t ff tCrawl the dataspace and provide best-effort query answers over crawled data.
VisiNav (DERI, Ireland)
Falcons (IWS, China)
Sig.ma (DERI, Ireland)
Swoogle (UMBC, USA)
W t (O U i it UK)Watson (Open University, UK)
Christian Bizer: Europeana Conference (05/10/2010)
Christian Bizer: Europeana Conference (05/10/2010)
Christian Bizer: Europeana Conference (05/10/2010)
What are the big players doing?
Christian Bizer: Europeana Conference (05/10/2010)
Yahoo!
crawls Linked Data in its RDFa serialization as well as Microformats.
provides access to crawled data through the Yahoo BOSS API provides access to crawled data through the Yahoo BOSS API
is using the data within Yahoo Search Monkey to make search results more useful and visually appealing.more useful and visually appealing.
Christian Bizer: Europeana Conference (05/10/2010)
uses crawled data to enhance search results snippets and to feed its Social Graph APIand to feed its Social Graph API
is developing Google Squared and Google Fusion Tables
has recently bought MetaWeb which maintains Freebase, a DBpedia/YAGO competitor, p p
is starting to use structured data in its applications
Christian Bizer: Europeana Conference (05/10/2010)
Conclusion
Linked Data provides best practices for publishing structured data on the Webstructured data on the Web Simple set of standards: RDF, URIs, HTTP
E bl t d di d f id f t l Enables standardized access for wide range of tools:browsers, crawlers, mashups
Th W b f Li k d D t i i idl The Web of Linked Data is growing rapidly Active deployment communities exist in various domains
H d d th iti l Has exceeded the critical mass
Web search is evolving into query answering Search engines will increasingly rely on structured data from the Web
We are getting closer to being able to use the Web like aWe are getting closer to being able to use the Web like a global distributed database.
Christian Bizer: Europeana Conference (05/10/2010)
Thanks!
References Christian Bizer, Tom Heath, Tim Berners-Lee: Linked Data – The Story So Far
h // h h / /bi h h b l ij i li k d d dfhttp://tomheath.com/papers/bizer-heath-berners-lee-ijswis-linked-data.pdf
Linking Open Data Project Wiki http://esw w3 org/topic/SweoIG/TaskForces/CommunityProjects/LinkingOpenDatahttp://esw.w3.org/topic/SweoIG/TaskForces/CommunityProjects/LinkingOpenData
3rd Linked Data on the Web Workshop at WWW2010http://events.linkeddata.org/ldow2010/
Christian Bizer: Europeana Conference (05/10/2010)