Linked (Open) Data

Linked (Open) Data

Opportunities and challenges

Makx [email protected]

Outline

• Basic notions• Recent developments• Comparing objectives• Opportunities and risks• Conclusions

© 2011 Makx Dekkers Journeés ABES 2011 2

BASIC NOTIONS


The idea and its history

• 1989: Tim Berners-Lee already talked about linking documents and data together (http://www.w3.org/History/1989/proposal.html)

• 2001: Tim Berners-Lee and Ora Lassila introduced the “Semantic Web” (http://www.scientificamerican.com/article.cfm?id=the-semantic-web)

• 2006: Tim Berners-Lee presented the initial design issues (rules) for Linked Data (http://www.w3.org/DesignIssues/LinkedData.html)


http://www.w3.org/History/1989/proposal.html

http://www.scientificamerican.com/article.cfm?id=the-semantic-web

http://www.w3.org/DesignIssues/LinkedData.html

W3C Semantic Web initiative

• Objective– to create a universal medium for the exchange of

data […] to smoothly interconnect personal information management, enterprise application integration, and the global sharing of commercial, scientific and cultural data

• Main results– Resource Description Framework (RDF), RDFa

(RDF-in-HTML), SPARQL Query Language


Core Linked Data Specifications

• Transport– HTTP Hypertext Transfer Protocol

• Identification– URI Uniform Resource Identifier

• Description and linking– RDF Resource Description Framework

• Search and access– SPARQL Query Language for RDF


The four rules of Linked Data

• TBL’s recommendations:1. Use URIs as names for things2. Use HTTP URIs so that people can look up those

names3. When someone looks up a URI, provide useful

information, using the standards (RDF*, SPARQL)4. Include links to other URIs so that they can

discover more things


The basic model of RDF

• Resource Description Framework “triple”:– Subject: the “thing” (resource) described– Predicate: the characteristic of the resource– Object: the value of the characteristic

Subject ObjectPredicate


Complex structures in RDF

This presentation

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Linked (Open / Enterprise) Data

• Commonalities– Using Semantic Web technologies (RDF)– Linking information resources, people, places

• Differences– Open Data with open licenses; Enterprise Data

mostly for closed, controlled environments– Open Data links to other Open Data, available for

external use; Enterprise Data may link to external data but not openly available for external use


Linked Data -- Open Data

• Linked Data: focus on technology– Semantic Web: Resource Description Framework,

and other Web standards– Final solutions still under development

• Open Data: focus on strategy– Based on notion that sharing is important and

benefits all– Technology is secondary


The five-star system

Source: http://inkdroid.org/journal/2010/06/04/the-5-stars-of-open-linked-data/


http://inkdroid.org/journal/2010/06/04/the-5-stars-of-open-linked-data/

The LOD diagram: 2007

Linking Open Data cloud diagram, by Richard Cyganiak and Anja Jentzsch. http://lod-cloud.net/


25 datasets




45 datasets




95 datasets




203 datasets

RECENT DEVELOPMENTS


W3C communities

• LinkingOpenData SWEO Community Project– Goal: to extend the Web with a data commons by

publishing various open data sets as RDF on the Web and by setting RDF links between data items from different data sources (http://www.w3.org/wiki/SweoIG/TaskForces/CommunityProjects/LinkingOpenData)

• Library Linked Data Incubator Group– to help increase global interoperability of library

data on the Web (http://www.w3.org/2005/Incubator/lld/)


http://www.w3.org/wiki/SweoIG/TaskForces/CommunityProjects/LinkingOpenData

http://www.w3.org/2005/Incubator/lld/

More W3C communities

• Government Linking Data Working Group– to provide standards and other information which

help governments around the world publish their data as effective and usable linked data (http://www.w3.org/2011/gld/charter)

• Semantic Web Health Care and Life Sciences (HCLS) Interest Group– to develop, advocate for, and support the use of

Semantic Web technologies for health care and life science (e.g. biology, medicine) (http://www.w3.org/2001/sw/hcls/)


http://www.w3.org/2011/gld/charter

http://www.w3.org/2011/gld/charter

http://www.w3.org/2001/sw/hcls/

http://www.w3.org/2001/sw/hcls/

Open Knowledge Foundation, okfn.org

• not-for-profit organization promoting open knowledge: any kind of data and content that can be freely used, reused, and redistributed

• Working and Interest Groups, e.g.– Open Data in Science, Open Government Data,

Open Bibliographic Data, Cultural Heritage etc.

• CKAN.net: registry of open datasets and other “knowledge resources”


Linked Data initiativesPredicate vocabularies (descriptors)

Research Description and Access (RDA) http://metadataregistry.org/rdabrowse.htm

The Bibliographic Ontology (BIBO) http://bibliontology.com/

Dublin Core http://dublincore.org/

Object vocabularies (values)

Virtual International Authority File (VIAF) http://viaf.org/

Library of Congress authorities http://id.loc.gov/authorities/

AgroVOC (agricultural terminology) e.g. http://aims.fao.org/aos/agrovoc/c_550

DBPedia (based on Wikipedia) e.g. http://dbpedia.org/page/Montpellier

Bibliographic data

LIBRIS Sweden e.g. http://libris.kb.se/library/S

British Library http://www.bl.uk/bibliographic/datasamples.html

CrossRef (DOI metadata) http://www.crossref.org/CrossTech/linked_data/


http://metadataregistry.org/rdabrowse.htm

http://bibliontology.com/

http://dublincore.org/

http://viaf.org/

http://id.loc.gov/authorities/

More Linked Data initiativesBroadcasting, publishing

BBC http://www.bbc.co.uk/blogs/bbcinternet/linked_data/

New York Times http://data.nytimes.com/

Governments (small sample)

USA http://data.gov/

France http://opendata.paris.fr/

Finland http://data.suomi.fi/

UK http://data.gov.uk/

Spain (Cataluña) http://dadesobertes.gencat.cat/

Norway http://data.norge.no

Netherlands http://www.overheid.nl/opendata

Australia http://data.gov.au/


COMPARING OBJECTIVES


Strategic aspects Linked Data

• Achieving global interoperability with minimal coordination

• Aggregating human knowledge• Supporting democracy, transparency and

accountability• Enhancing and enriching information• Enabling user-driven and user-generated

applications


Strategic aspects libraries

• Organizing information for use by specific users for specific goals

• Ensuring and maintaining quality• Sustaining services economically• Preserving information for the long term• Providing trusted services


Functional aspects Linked Data

• Searching distributed collections • “Following your nose” – navigating links

between pieces of content• Distributing responsibility for making

statements about things• Leaving to the user whom and what to trust• Leaving development of products and services

to an open market (apps)


Functional aspects libraries

• Describing information by professionals• Bringing together and managing aggregations

of information• Selecting relevant information• Mixing analogue and digital resources


Technical aspects Linked Data

• Publishing and using machine-readable statements (“data that speak for themselves”)

• Focusing on Semantic Web technology• Enabling inferences across large distributed

data sets• (Still to be done) Solving issues around

harvesting, caching and real-time updating


Technical aspects libraries

• Using proven technology to provide high-quality services

• Managing production systems and services• Guaranteeing performance, uptime,

consistency across data


Agility versus sustainability

• In the Linked Data space:– Things move fast– Trial-and-error– Lots of development by volunteers (hackers)

• In the library domain:– Operational systems need to evolve– Need to handle legacy data– Development by professionals in managed

projects


Data versus services

• In the Linked Data space:– Focus on availability of “raw data”– Quality is secondary– Data and technology should lead to useful results

• In the library domain:– Focus on services– Quality is essential– Data and technology in support of the service


Economic aspects

• In the Linked Data space:– “Information wants to be free” – a human right?– Short-term thinking: today is hot, yesterday is not – Focus on applications to create value out of data

• In the library domain:– Long-term view: sustainability is crucial– Public money to provide community services– Expected to do more with less money


OPPORTUNITIES AND RISKS


Strong points Linked Data

• Attempt to create a common technical platform for machine-readable data

• Lots of enthusiasm in publishing open data• Promise of global interoperability• Mix of researchers, user communities,

hackers, professional data providers• High visibility on political level


Risks Linked Data

• Driven by technology, not by requirements• Technology may not (yet) be stable – RDF 2.0?• Operational issues far from solved (reliability,

performance, quality, security, trust) • Hope for general agreement across domains

may not be realistic• Promise may turn into disappointment


Strong points libraries

• Long time operational experience in managing information

• Professional intermediaries between users and information needs

• Sustainable business models (albeit with eternally shrinking budgets)

• Long-term perspective: the past (legacy data) as well as the future (preservation)


Risks libraries

• Technologies change rapidly• New skills difficult to spread through the

organization• Some people see libraries as a thing of the

past (“the book museum”)• Underestimation of information handling skills• Information overload, human intervention

does not scale, need for better tools


Meeting both worlds

• An example: Europeana.eu– Started out with domain perspectives (libraries,

archives, museums, audiovisual archives)– “Traditional” approach (metadata mappings)

works but insufficient– Using Linked Data approach preserves domain

specifics but allows for generalization to support common services

– Cross-domain (but co-ordinated) interoperability


Europeana Data ModelClasses Properties

Simple example

Complex example

Source at:http://version1.europeana.eu/web/europeana-project/technicaldocuments/


CONCLUSION


Libraries and Linked Data

• Using Linked Data technology as the next step in connecting services

• Offering information management skills to the technology domain

• Creating a quality hub in the Linked Data space


Best of both worlds

• Libraries providing stability and sustainability to Linked Data spaces

• Library professionals helping to manage the distributed collections

• Libraries delivering high-quality linked data to the Web

• Technologists to provide the next generation of systems and tools


Linked (Open) Data: opportunity for libraries!

Thank you!

Makx [email protected]

Documents

Linked (Open) Data