Linked Data Evolving the Web into a Global Data Space

Transcription

1 Linked Data Evolving the Web into a Global Data Space Anja Jentzsch, Freie Universität Berlin 05 October 2011 EuropeanaTech 2011, Vienna 1

2 Architecture of the classic Web Single global document space Web Browsers Search Engines Small set of simple standards 1. HTML as document format 2. HTTP URLs as globally unique IDs retrieval mechanism HTML hyperlinks HTML HTML 3. Hyperlinks to connect everything A B C 2

3 Web 2.0 APIs and Mashups No single global data space Shortcomings 1. APIs have proprietary interfaces Mashup 2. Mashups are based on a fixed set of data sources 3. No hyperlinks between data items within different APIs Web API Web API Web API Web API A B C D 3

4 Web APIs slice the Web into Walled Gardens Image: Bob Jagensdorf, CC-BY 4

5 Linked Data Extend the Web with a single global data space 1. by using RDF to publish structured data on the Web 2. by setting links between data items within different data sources RDF RDF RDF RDF RDF RDF RDF RDF RDF RDF RDF Links RDF Links RDF Links RDF Links A B C D E 5

6 Linked Data Principles Set 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 things. 2. Use HTTP URIs so that people can look up those names. 3. When someone looks up a URI, provide useful RDF information. 4. Include RDF statements that link to other URIs so that they can discover related things. Tim Berners-Lee,

7 The RDF Data Model pd:chris rdf:type foaf:person foaf:name Chris Bizer foaf:based_near dbpedia:berlin 7

8 Data Items are identified with HTTP URIs pd:chris rdf:type foaf:person foaf:name Chris Bizer foaf:based_near dbpedia:berlin pd:chris = dbpedia:berlin = 8

9 Resolving URIs over the Web rdf:type pd:chris foaf:person foaf:name Chris Bizer foaf:based_near dp:population dbpedia:berlin skos:subject dp:cities_in_germany 9

10 Dereferencing URIs over the Web rdf:type pd:chris foaf:person foaf:name Chris Bizer foaf:based_near dp:population dbpedia:berlin skos:subject dbpedia:hamburg skos:subject skos:subject dp:cities_in_germany dbpedia:muenchen 10

11 Properties of the Web of Linked Data Global, distributed data space build on a simple set of standards RDF, URIs, HTTP Entities are connected by links creating a 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 express their personal view on things Everybody can use the vocabularies/schema that they like 11

12 W3C Linking Open Data Project Grassroots community effort to publish existing open license datasets as Linked Data on the Web interlink things between different data sources 12

13 LOD Data Sets on the Web: May data sets Over 500 million RDF triples Around 120,000 RDF links between data sources 13

14 LOD Data Sets on the Web: November data sets 14

15 LOD Data Sets on the Web: September data sets Over 2 billion RDF triples 15

16 LOD Data Sets on the Web: July data sets Over 6.5 billion RDF triples 16

17 LOD Data Sets on the Web: September data sets Over 24,7 billion RDF triples Over 436 million RDF links between data sources 17

18 LOD Data Sets on the Web: September data sets Over 31 billion RDF triples Over 504 million RDF links between data sources 18

19 LOD Data Set statistics as of 09/2011 LOD Cloud Data Catalog on CKAN More statistics 19

20 DBpedia The Hub on the Web of Data DBpedia is a joint project with the following goals extracting structured information from Wikipedia publish this information under an open license on the Web setting links to other data sources Partners Freie Universität Berlin (Germany) Universität Leipzig (Germany) OpenLink Software (UK) neofonie (Germany)

21 Extracting structured data from Wikipedia

22 Extracting structured data from Wikipedia! dbpedia:berlin rdf:type dbpedia-owl:city,!! dbpedia-owl:populatedplace,!! dbpedia-owl:place ;! rdfs:label ;! dbpedia-owl:population ;! wgs84:lat ;! wgs84:long ! dbpedia:soundcloud dbpedia-owl:location dbpedia:berlin. access to DBpedia data: dumps SPARQL endpoint Linked Data interface

23 The DBpedia Data Set Information on more than 3.64 million things 416,000 persons 169,000 organisations 526,000 places 106,000 music albums 60,000 movies 183,000 species 24,000 books overall more than 1 billion RDF triples title and abstract in 97 different languages 2,724,000 links to images 6,300,000 links to external web pages 6,200,000 links to other Linked Data sets

24 DBpedia Mappings since March 2010 collaborative editing of DBpedia ontology mappings from Wikipedia infoboxes and tables to DBpedia ontology curated in a public wiki with instant validation methods multi-langual mappings to the DBpedia ontology: ca, de, el, en, es, fr, ga, hr, hu, it, ko, nl, pl, pt, ru, sl, tr allows for a significant increase of the extracted data s quality each domain has its experts

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26 DBpedia Mobile displays Wikipedia data on map aggregates different data sources

27 Faceted Wikipedia Search

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29 Uptake in the Government Domain The EU is pushing Linked Data (LOD2, LATC, Eurostat) W3C Government Linked Data (GLD) Working Group

30 Uptake in the Libraries Community Institutions publishing Linked Data Library of Congress (subject headings) German National Library (PND dataset and subject headings) Swedish National Library (Libris - catalog) Hungarian National Library (OPAC and Digital Library) British National Library Europeana project 30

31 Uptake in the Libraries Community W3C Library Linked Data Incubator Group (2010) OKFN Working Group on Bibliographic Data (2010) Goals: Integrate Library Catalogs on global scale Interconnect resources between repositories (by topic, by location, by historical period, by...) 31

32 Uptake in the Media Industry Publish data as RDF/XML or RDFa Goal: Drive traffic to websites via search engines 32

33 Connecting the classic Web with the Web of Data Annotate Web documents with Linked Data URIs < dc:subject < Goals Connect everything Display Web of Data content as info boxes next to news or blog posts Improve search by using Linked Data as background knowledge (Semi-) Automated Annotation Services using Named Entity Recognition Open Calais (Thomsons Reuters) for news Zemanta (startup) for blog posts DBpedia Spotlight 33

34 Linked Data Applications Linked Data Browsers Linked Data Mashups Search Engines Thing Thing Thing Thing Thing Thing Thing Thing Thing Thing typed links typed links typed links typed links A B C D E 34

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38 Lower Data Integration Costs The overall data integration effort is split between the data publisher, the data consumer and third parties. Data Publisher publishes data as RDF sets identity links reuses terms or publishes mappings Third Parties set identity links pointing at your data publish mappings to the Web Data Consumer has to do the rest using record linkage and schema matching techniques 38

39 How to publish Linked Data Tasks: 1. Make data available as RDF via HTTP 2. Set RDF links pointing at other data sources 3. Make your data self-descriptive 4. Reuse common vocabularies Tom Heath, Christian Bizer: Linked Data: Evolving the Web into a Global Data Space 39

40 Is your data 5 star? Make your stuff available on the Web (whatever format) under an open license. Make it available as structured data (e.g., Excel instead of image scan of a table) so that it can be reused. Use non-proprietary, open formats (e.g., CSV instead of Excel). Use URIs to identify things, so that people can point at your stuff and serve RDF from it. Link your data to other data to provide context. Tim Berners-Lee,

41 Conclusion Linked Data provides a standardized data access interface Linked Data allows for the development of a variety of tools to integrate, enhance and and view the data The Web of Data is growing rapidly There are active deployment communities in different domains Web search is evolving into query answering Search engines will increasingly rely on structured data from the Web 41

42 Thanks Questions? References Tom Heath, Christian Bizer: Linked Data: Evolving the Web into a Global Data Space Christian Bizer, Tom Heath, Tim Berners-Lee: Linked Data The Story So Far Linking Open Data Project Wiki 42