Linking Open Data

Linked Open Data: Principles & 2 Projects Prof. Dr. Stefan Gradmann Humboldt-Universität zu Berlin / School of Library and Information Science [email_address]

Overview
Linked Data: What is it, how does it work?
LoD & LOD2: two projects
Conclusion : on the importance of being 'open'

From the Web of Documents to the Linked Data Web The Document Web: Information Management: A Proposal (TBL, 1989). Built on
Documents („Information Resources“)
Untyped HTTP links
The Web of Linked Open Data can be understood as an extension of the document web
In syntax (RDF)
In scope (including re- presentations of non- information resources, 'things', 'data')

Syntactically Extending the Document Web (1)
We add a syntax for making statements on resources: RDF
Or, more generally triples ...
… where S and P are web resources (identified using URIs) and O is either a web resource or a literal

Syntactically Extending the Document Web (2)
We add a schema language (RDFS) with elements such as
classes,
hierarchies of classes and properties,
inheritance
support for basic inferencing.
And thus are able to establish structures in triple aggregations resulting in lightweight domain ontologies:

Extending the Web in Scope: the way it does not work! Taken from Ronald Carpentier's Blog at http://carpentier.wordpress.com/ 2007/08/08/1-2-3/ Something is wrong with this picture (but what?)

… and the way extending the Web in scope is actually done: A Web of Things

A few Bubbles: 5/2007 < Over 500 million RDF triples < Around 120,000 RDF links between data sources © Richard Cyganiak

Quite some Bubbles: 9/2008 © Richard Cyganiak

Many Bubbles: 7/2009 © Richard Cyganiak < Over 13.1 billion RDF triples < Over 142 million RDF links between data sources

(Too?) Many Bubbles: 9/2010 http://richard.cyganiak.de/2007/10/lod/lod-datasets_2010-09-22_colored.html

EDM and Linked Open Data
Europeana Information Space
Context Data
DBpedia
PND and SWD (prototype)
Geonames
LCSH
…

Linking Open Data
Initiative of the Semantic Web Education and Outreach (SWEO) interest group of W3C http://www.w3.org/wiki/SweoIG/TaskForces/CommunityProjects/LinkingOpenData
“ The goal [...] is to build a data commons by making various open data sources available on the Web as RDF and by setting RDF links between data items from different data sources.”
First gathering in Banff at WWW2007 with pioneers such as Tom Heath , Chris Bizer , Kingsley Idehen, Yrjana Rankka, Orri Erling, Ivan Mikhailov, Danny Ayers, Steve Coast, Peter Murray Rust, Alan Ruttemberg, Ian Horrocks, Bernardo Cuenca Grau, Boris Motik, Danny Gagne.
Current discussion: how to switch from mere volume to quality ? Matching, mapping and referrals are central
Tom Heath and Christian Bizer (2011) Linked Data: Evolving the Web into a Global Data Space (1st edition). Morgan & Claypool. http://linkeddatabook.com/editions/1.0/

LOD2
Large-scale integrating project co-funded by the European Commission within the FP7 framework (09/2010 – 08/2014, Total Budget: 8,58 M€, Total Funding: 6,45 M€, Total Resources: 844 PM) -> http://lod2.eu/Welcome.html
Builds on the Linked Open Data cloud and extends it with a technology stack for enabling application building . The stack includes:
Comprehensive Knowledge Archive Network (CKAN, registry)
D2R Server (Relational to RDF)
DBPedia Extraction from Wikipedia
OntoWiki (agile, distributed knowledge engineering)
Silk Link Discovery Framework
Openlink Virtuoso (data, information, and knowledge management)
Consortium: Universität Leipzig (Sören Auer, lead), Centrum Wiskunde & Informatica, Digital Enterprise Research Institut (DERI), Freie Universität Berlin, OpenLink Software, Semantic Web Company, TenForce, Exalead, Wolters Kluwer, Open Knowledge Foundation

… and the political bit

On the Importance of being 'Open' (1)
“ Openness (allowing access) is separate question.” (TBL, http://www.w3.org/2008/Talks/0617-lod-tbl/#(22))
Does Linked Data work without being 'open' ?
Technically speaking: yes (cf. pharma industry or biomedical data)
But it gets quite expensive that way …
… much too expensive, probably, for Europeana to afford!
Or else (LD behind a proxy) it is straightaway parasitic.
And much of its 'semantic' charms of open flow of RDF statements and reasoning potential would be lost in such a setting, anyway.
As a consequence, we aim at Europeana data being Open Linked Data (more in a Europeana Foundation statement at http://bit.ly/fe637P ) and at Europeana data being under CC0!

On the Importance of being 'Open' (2)
This has a number of implications
No control over data usage
No income to be generated from data access and use
Innovative and (commercially) attractive services can be built on LoD
-> Do not repeat mistakes we are very familiar with from the Open Access debates of the past 10 years!
'open' = 'free',
'free' vs. 'commercial'
-> Do not exclude commercial reuse for Europeana metadata!
-> What is the actual value of context (in business terms!)?

Thank you for your attention!

Linking Open Data

by Stefan Gradmann on May 15, 2011

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Linking Open Data — Presentation Transcript