introduction to apis and linked data
DESCRIPTION
Talk given at Open Knowledge Foundation 'Opening Up Metadata: Challenges, Standards and Tools' Workshop, Queen Mary University of London, 13th June 2012. Info on the event at http://openglam.org/2012/05/31/last-places-left-for-opening-up-metadata-challenges-standards-and-tools/TRANSCRIPT
Adrian StevensonSenior Technical Innovations Coordinator
Mimas, University of Manchester, UK
@adrianstevenson
Introduction to APIs and Linked Data
Benefits of APIs for GLAMs
• Cross-searching• Improved resource discovery• Data not trapped in silos• Findability on the Web – Google• Data re-use• Bringing data together - integration• Enhanced services – e.g. Mashups
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Metadata
• What is it? - Data about data• How do you create it?
– Catalog card, text editor, Word, Excel, Access, XML Editor….
• Do you use standards?– EAD – Encoded Archival Description– Not using standards may have implications for
interoperability & sustainability
• How do you move it around?– CDs, Email attachments, FTP, APIs
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What is an API?
• ‘Application Programming Interface’
– “API is an online interface that allows distributed systems to communicate with one another and exchange information”
– “APIs are carefully thought out pieces of code created by programmers .. that allow other applications to interact with their application”
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APIs
• Allow machine readability of data– Typically over the Web
• Provide other systems with access to content or functions
• Many types – e.g.– Google, Facebook, Flickr, twitter APIs ….– OAI-PMH– Linked Data API, SPARQL– Others include SOLR, SRU, Z39.50, SOAP, ….
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APIs are Machine to Machine
• API is software-to-software interface, not a user interface
• E.g. Cinema ticket websites use API:– Sends credit card info to remote application– Remote application sends response back to
ticket website saying OK to issue the tickets • User see one interface
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Mashups
8http://www.vistory.nl/Data from www.openimages.eu/api
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Twitter API
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https://dev.twitter.com/
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https://developers.google.com/google-apps/spreadsheets/
Open Expenses
12http://benosteen.wordpress.com/2010/02/27/giving-the-mps-a-receipt-for-their-expenses-claim/
OAI-PMH
• Open Archive Initiative Protocol for Metadata Harvesting
• Mechanism for repositories and services to share metadata over the Web
• Facilitates cross-searching• Works by use of 6 ‘verbs’
– E.g. ListMetadataFormats, ListRecord, GetRecord …– http://archiveshub.ac.uk/api/OAI-PMH/2.0/hub?verb=Identify– http://archiveshub.ac.uk/api/OAI-PMH/2.0/hub?verb=
GetRecord&identifier=gb141vbh&metadataPrefix=oai_dc
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OAI-PMH: GetRecord
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http://oaister.worldcat.org/
Linked Data
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“The term Linked Data refers to a set of best practices for publishing and connecting structured data on the Web.”
“the Semantic Web is the goal or end result… Linked Data provides the means to reach that goal”
From ‘Linked Data: The Story So Far’ - Heath, Bizer and Berners-Lee 2009
The goal of Linked Data is to enable people to share structured data on the Web as easily as they can share documents today.Bizer/Cyganiak/Heath Linked Data Tutorial, linkeddata.org
Linked Data Design Issues
• URIs• LD Design Issues• Triples
http://www.w3.org/DesignIssues/LinkedData.html
URIs and HTTP
• “A Uniform Resource Identifier’ (URI) provides a simple and extensible means for identifying a resource” – W3C RFC 3986
• HTTP URIs may be ‘de-referenced’on the Web
• HTTP URIs are used for “real world” things• http://adrianstevenson.com/id/me• http://dbpedia.org/resource/Love
RDF
• Resource Description Framework– a language for representing information about
resources on the Web– RDF can be used to represent things identified
on the Web, even when they cannot be directly retrieved on the Web
• Describes relations using ‘triples’
• http://www.w3.org/TR/REC-rdf-syntax/
Triples
• Triples statements– ‘Things’ have ‘properties’ with ‘values’– Subject – Predicate - Object
• Triples are the basis of RDF and Linked Data
ArchivalResource
Repository Provides Access To
The Rolling Stones
Keith Richards Is Member Of
Archives Hub Model
From RDF to Linked Data
• If something is identified, it can be linked to• We take items from our datasets and link
them to items from other datasets
BBCVIAF
DBPedia
Archives Hub
Copac
GeoNames
http://data.archiveshub.ac.uk/
http://data.archiveshub.ac.uk/id/person/nra/webbmarthabeatrice1858-1943socialreformer
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http://archiveshub.ac.uk/linkinglives/
http://wraggelabs.com/shed/presentations/anzi
Key Benefit of Linked Data
• Web 2.0 mashups work against a fixed set of data sources• Hand crafted by humans• Don’t integrate well
• Linked Data promises an unbound global data space• Easy dataset integration• Generic ‘mesh-up’ tools
Benefits for GLAMs
• Cross-searching• Improved resource discovery• Data not trapped in silos• Findability on the Web – Google• Data re-use• Bringing data together - integration• Enhanced services
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Linked Data Challenges
• Dirty data, URI persistence• Steep learning curve• Complexity• How sustainable are the data sources?• How scalable are triple stores?• Can you track the provenance of data
sources?• Licensing
• are data licensing issues covered?
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Contact
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Adrian StevensonMimas, University of Manchester, [email protected]
www.mimas.ac.uk
@adrianstevensonwww.linkedin.com/in/adrianstevensonwww.slideshare.net/adrianstevenson
CC License
• This presentation available under creative commons Non Commercial-Share Alike:
http://creativecommons.org/licenses/by-nc/2.0/uk/