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What is Linked Data,
and What Does It Mean for Libraries?
Emily Dust NimsakontALAO TEDSIG Spring
MeetingMay 27, 2011
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This is an overview…
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• What is Linked Data?• How do we create Linked Data?• Examples of Linked Data• What does Linked Data mean for libraries?• Are there drawbacks to Linked Data?• What’s next?• What can I do?
What is Linked Data?
Wikipedia says…
“Linked Data describes a method of publishing structured data, so that it can be interlinked
and become more useful. It builds upon standard web technologies, such as HTTP and
URIs - but rather than using them to serve web pages for human readers, it extends them to share information in a way that can be read
automatically by computers.”
http://en.wikipedia.org/wiki/Linked_Data
The inventor of the Web said…
“I have a dream for the Web [in which computers] become capable of analyzing all
the data on the Web – the content, links, and transactions between people and computers.”
Tim Berners-Lee, 1999
Linked Datavs.
Semantic Webvs.
Web 3.0
web of documentsvs.
web of data
resource
resource
resource
resource
resource links to
links to
links to
links to
data links to
links to
links to
links to
data data
data
datadata
datadata
datadata
data
data
hypertextvs.
hyperdata
HTML
<h1>This is a heading.</h1>
<p>This is a paragraph.</p>
RDF/XML
<rdf:Descriptionrdf:about="http://www.recshop.fake/cd/Empire Burlesque"> <cd:artist>Bob Dylan</cd:artist> <cd:country>USA</cd:country> <cd:company>Columbia</cd:company> <cd:price>10.90</cd:price> <cd:year>1985</cd:year></rdf:Description>
http://www.w3schools.com/rdf/rdf_example.asp
Relationships are key
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People can understand relationships between things.
But machines should be able to understand these relationships too.
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We are used to connecting pieces of information based on their context.
Title: A Christmas CarolAuthor: Charles Dickens
Linked Data makes the relationships explicit.
1. Data instead of documents2. Encoded meaning3. Relationships are key
So what?
Linked Data makes the Web into a database.
“Linked Open Data turns the Web into an API.”
Corey A. Harperas quoted in
http://www.slideshare.net/eby/why-libraries-should-embrace-linked-data
Linked Data allows you to customize the Web.
“Link your data to other people’s data to provide context.”
Michael Hausenblashttp://webofdata.wordpress.com/2011/05/22/why-we-link/
Questions?
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How do we create Linked Data?
Linked Data principles
Tim Berners-Lee, “Linked Data-Design Issues.” http://www.w3.org/DesignIssues/LinkedData.html
Use URIs as names for
things
Use HTTP URIs so people can look up these names
When someone looks up a URI, provide
useful information, using the standards
Include links to other URIs, so that they can discover more
things
URIs
For Linked Data, we need to be able to identify things uniquely
Uniform Resource Identifiers do this already
URIs
Using HTTP URIs is one of the principles of Linked Data
http://www.example.com/thing1
URIs
URIs are like control numbers (LCCN, ISBN, etc.).
RDF
Resource Description Framework
Describes relationships based on triples (statements):
subject-predicate-object
http://www.w3.org/RDF
RDF
subject object
A Christmas Carol
Charles Dickens
has author
predicate
RDF statements
The subject and predicate must be URIs.
The object can be a URI or a value.
RDF graphs
Charles Dickens
A Christmas
Carol
has author has
publisher
Penguin
RDF
<rdf:Descriptionrdf:about="http://www.recshop.fake/cd/Empire Burlesque"> <cd:artist>Bob Dylan</cd:artist> <cd:country>USA</cd:country> <cd:company>Columbia</cd:company> <cd:price>10.90</cd:price> <cd:year>1985</cd:year></rdf:Description>
http://www.w3schools.com/rdf/rdf_example.asp
Vocabularies
Specific terms to be used to describe resources
Sound familiar?
Vocabularies
• Dublin Core• Simple Knowledge Organization System (SKOS)• RDF Schema (RDFS)• Friend of a Friend (FOAF)• Web Ontology Language (OWL)
<rdf:RDF xmlns:dcterms="http://purl.org/dc/terms/" xmlns:owl="http://www.w3.org/2002/07/owl#" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:skos="http://www.w3.org/2004/02/skos/core#">
<skos:prefLabel> Knitting</skos:prefLabel>
SPARQL
• SPARQL is a query language (like SQL) used to search the semantic web
• SPARQL endpoints are provided for Linked Data resources
Link to other resources
1. Relationship Links2. Identity Links3. Vocabulary Links
Questions?
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Are there examples of Linked Data/
Semantic Web?
Questions?
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What could Linked Data
mean for Libraries?
Part I:What could Linked Data
mean for Library Data?
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Getting rid of silos
“Our services must not only be on the Web, but need to be of the
Web.”- Karen Coyle
RDA Vocabularies for a Twenty-First-Century Data EnvironmentLibrary Technology Reports
February 2010
Library Catalogs
World Wide Web
More open standards
bibliographic recordsvs.
bibliographic data
In traditional cataloging, a record is one package.
Author
Title
Bibliographic Record
Bibliographic Record
Records can be exchanged, but there is no way to exchange the individual pieces of information within a record.
Bibliographic Record
Bibliographic Record
Person
Is author of
Title
Bibliographic Record
With Linked Data, a bibliographic record is made up of many pieces of data.
And the relationships between these pieces of data are defined.
Person
Is author of
Title
Bibliographic RecordThe boundaries of the record can be dissolved…
Person
Is author of
Title
Bibliographic Record…and the data can interact with other information on the Web.
Are there examples of Linked Data in
libraries?
RDA Metadata Registry
http://metadataregistry.org/rdabrowse.htm
So there’s a bunch of data out there.
Now what?
What does Linked Data look like?
“That is kind of like asking what electricity looks like: it doesn’t so much look like anything, as it makes certain things possible.”
Karen CoyleVisualizing Linked Data
http://kcoyle.blogspot.com/2011/04/visualizing-linked-data.html
Part II:What Could Linked Data
Mean for Librarians?
Different workflows
Catalogers could use URIs for things like authors’ names or subject headings.
If information changed, the URI could be changed and automatically update the
information in our catalogs.
Evaluating metadata
Metadata could come from various sources.
“Professional cataloging might be more of a job of aggregating and improving harvested or
contributed metadata, rather than developing new metadata, like MARC records, for
resources.”-Virginia Schilling
“The Catalogers’ Revenge: Unleashing the Semantic Web”PNLA Quarterly 74:3, 2010
http://unllib.unl.edu/LPP/PNLA%20Quarterly/schilling74-3.pdf
Federated searching
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New homes for librarians’ skills?
“Someday there will be a Dewey Decimal number for everything – not just for books.”
http://www.pcworld.com/businesscenter/article/206230/the_internet_needs_a_dewey_decimal_system.html
Are There Drawbacks to Linked
Data?
Training and Software Development
“Nobody but the geekily inclined is going to be willing to invest the time and effort necessary to code semantically tagged web pages from
scratch.”
Virginia Schilling“The Catalogers’ Revenge: Unleashing the Semantic Web.”
PNLA Quarterly 74:3 (Spring 2010).
Access to the Data
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Different Standards and Vocabularies
http://www.dlib.indiana.edu/~jenlrile/metadatamap/
Reliability of Data
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What’s next?
Library Linked Data Incubator Group
http://www.w3.org/2005/Incubator/lld/
International Linked Open Data in Libraries, Archives, and Museums Summit - June 2-3, 2011
http://lod-lam.net
Linked Data at ALA Annual 2011
What can I do?
5 Stars of Open Linked Data
★ Available on the web (whatever format), but with an open license
★★ Available as machine-readable structured data (e.g. Excel instead of image scan of a table)
★★★ Available as (2) plus non-proprietary format (e.g. CSV instead of Excel)
★★★★ 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
http://www.w3.org/DesignIssues/LinkedData.html
Laura Smart, California Institute of TechnologyManaging Metadata
http://library.caltech.edu/laura/
Resources• Jeffrey T. Pollock. Semantic Web for Dummies.• Toby Segaran, Colin Evans, and Jamie Taylor.
Programming the Semantic Web.• Tom Heath and Christian Bizer. Linked Data:
Evolving the Web into a Global Data Space.• Karen Coyle. “Understanding the Semantic
Web: Bibliographic Data and Metadata” and “RDA Vocabularies for a Twenty-First-Century Data Environment.” Library Technology Reports, ALA TechSource.
Linked Data is on the horizon.
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And it has the potential to greatly change how libraries work.
Thank you!
Emily Dust [email protected]
http://www.delicious.com/enimsakont/linkeddata+tedsighttp://www.slideshare.net/enimsakont
