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/

1. Introduction to APIs and
Linked Data
Adrian Stevenson
Senior Technical Innovations Coordinator
Mimas, University of Manchester, UK
@adrianstevenson

2. 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
2

3. 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
3

4. 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”
4

5. 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, ….
5

6. 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
6

7. Historypin
7
http://www.historypin.com

8. Mashups
8
Data from www.openimages.eu/api http://www.vistory.nl/

9. 9

10. Twitter API
10
https://dev.twitter.com/

11. 11
https://developers.google.com/google-apps/spreadsheets/

12. Open Expenses
12
http://benosteen.wordpress.com/2010/02/27/giving-the-mps-a-receipt-for-their-expenses-claim/

13. 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=o
ai_dc
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14. OAI-PMH: GetRecord
14

15. http://oaister.worldcat.org/
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16. Linked Data
“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
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17. 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

18. Linked Data Design Issues
• URIs
• LD Design Issues
• Triples
http://www.w3.org/DesignIssues/LinkedData.html

19. 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

20. 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/

21. Triples
• Triples statements
– „Things‟ have „properties‟ with „values‟
– Subject – Predicate - Object
Keith Richards Is Member Of The Rolling
Stones
Repository Provides Access To Archival
Resource
• Triples are the basis of RDF and Linked
Data

22. Archives Hub Model

23. 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
BBC
Copac
VIAF
DBPedia
GeoNames
Archives Hub

24. http://data.archiveshub.ac.uk/

25. http://data.archiveshub.ac.uk/id/person/nra/webbmarthabeatrice1858-1943socialreformer

26. 28
http://archiveshub.ac.uk/linkinglives/

28. http://wraggelabs.com/shed/presentations/anzi

29. 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

30. 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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31. 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
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32. Contact
Adrian Stevenson
Mimas, University of Manchester, UK
adrian.stevenson@manchester.ac.uk
www.mimas.ac.uk
@adrianstevenson
www.linkedin.com/in/adrianstevenson
www.slideshare.net/adrianstevenson
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33. CC License
• This presentation available under creative commons Non
Commercial-Share Alike:
http://creativecommons.org/licenses/by-nc/2.0/uk/