Linked Data and the OpenART Project

Tate, 7th October 2011Julie Allinson, University of YorkRichard StephensSteve Bayliss and Martin Dow, Acuity Unlimited

“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

Haven’t we been putting linked data on the web for years?

• The web is full of data, yes, but structure in traditional web pages is largely ‘formatting’

• And the ‘links’ are pretty unintelligent• Databases, search interfaces, XML etc are not

really integrated into the web, just on it• Web 2.0 services tend to work against a fixed

set of sources

links to exhibitions

links to galleries

Linked data

• Linked data is about identifying the ‘real-world’ things we want to describe

• and exposing rich information about these ‘things’

• in the form of links• linked data applications operate on top of

this unbound structured web of information– the www as one big database

RDF

• RDF (Resource Description Framework) is a way of modelling data, conceptually (as graphs)

• it links things, not just documents• and creates ‘typed’ links• allows us to say meaningful things about

entities• and the relationships between them

Triples• Triples are the basis of RDF• Triples statements

– Subject – Predicate - Object

• Rather than

The Snail

Gallery Displays

The Snail

Matisse Painted

Web Page

Web Page

Links to

One more thing about triples …

• If we want to do ‘linked’ data.• Each piece of the triple should be a link.• In web speak, that means a HTTP URI• A unique identifier• MAY be de-referenced to a location (a URL)• HTTP URIs are used to identify “real world”

things• http://dbpedia.org/resource/Snail• http://viaf.org/viaf/42630086/#Matisse,_Henri,_1869-1954

Linked

• The job of OpenART is to expose data• But linking is where it gets interesting• And where the (potential) value for linked

data starts to show

Some Examples …

Officially launched 21st January 2010

data.gov.uk

Visualisation Prototype• Using Timemap –

– Googlemaps and Simile

– http://code.google.com/p/timemap/

• Early stages with this• Will give location and

‘extent’ of archive.• Will link through to

Archives Hub

http://creativecommons.org/licenses/by-nc-sa/2.0/uk/

SIG.MA

Visualising multiple data sources

http://creativecommons.org/licenses/by-nc-sa/2.0/uk/

For discussion?

• Quality and Trust• Licensing• Control and Loss of Control• Hype Curve• Other approaches

OpenART : Open metadata for Art Research at the Tate

• JISC funded part of their Infrastructure for Resource Discovery Strand

• 6 months (March to July) – short!• £30k – cheap!• Building on the (much bigger) York’s History of Art

Department and Tate’s Court Country City project funded by the AHRC.

• The Digital Library are leading OpenART and providing technical development to Court Country City

• Acuity Unlimited are working with us on OpenART.

Doing what?

• designing and exposing linked open [meta]data for an important research dataset entitled "The London Art World 1660-1735", created as part of the AHRC funded Court, Country, City: British Art 1660 – 1735 project

And again, doing what?

• ‘The London Art World 1660-1735’ is set of spreadsheets, the result of several years research into Sources (sale catalogues, newspaper adverts) of information about Sales, People, and Places (and the things being sold) from the period

• The Digital Library is already helping put this information on the web.

• OpenART is extending this to create ‘linked open data’.

Snapshot from the Court Country City Web site

OpenART - in brief

• Take the spreadsheets• Anaylse them and model into an ontology• Decide how to create the linked data and how

to expose it to the web• Experiment a bit• Test and validate the ontology• Create the data and expose

Describing things with ontologies

• an ontology is a standardized representation of knowledge as a set of concepts within a domain, and the relationships between those concepts. It can be used to reason about the entities within that domain, and may be used to describe the domain (wikipedia)

• or, put another way “a way of describing things in a way other people/machines can understand” (me)

There are many ontologies out there

• Dublin Core is a simple ontology for describing web resources

• Geonames describes places

• For OpenART we have used two core event-based ontologies– Dolce Ultra-lite – Linked events (LODE)

and have extended these for the domain

Example!

• Much of the OpenART data set is about art sales, which are ‘events’

• Linked Events Ontology has a class for ‘Event’• Which we have specialized to create an

OpenART class for ‘Sale’• DUL has a class for ‘Social Agent’ (or person)• Which is a superclass for our term ‘Organiser’

Lost yet?

• What this means is that we can describe our dataset for a very narrow domain (people researching the art market)

• But it can be generalised and understood much more widely

• Because our narrow classes are members of broader, more general classes used in standard ontologies

Example (again)!

• Linked Events Ontology has a class for ‘Event’• Which we have specialized to create an

OpenART class for ‘Sale’• Someone only looking for ‘art sales’ in 1670

can answer their research question• Someone looking for ‘events’ in 1670 could

infer from our ‘Sale’ class that these sales are also events

http://creativecommons.org/licenses/by-nc-sa/2.0/uk/

OpenART output

• Unique identifiers for the primary entities (Sale, Source, Person, Place, and Artwork)

• RDF/XML (and probably ttl) documents representing each primary entity

• RDF/A embedded in the CCC web site• Owl:sameas statements for personal names

and VIAF

Lessons learnt

• Ontology development is hard work and needs sustaining and a community

• Linked data is simple in principle, but in application needs expertise and commitment

• The original data is semi-structured and this needs clean-up to fit the precision of the ontology

Final thoughts

• I believe there is a lot that could be done with open and linked data, by institutions

• … not least efficiencies, adding-value to local information, information sharing and resource discovery …

Contact Julie Allinson julie.allinson@york.ac.ukhttp://tinyurl.com/dlib-openart -- http://yorkdl.wordpress.com/

(thanks to Adrian Stevenson for some of the slides;

cover image: http://www.flickr.com/photos/bostonjal/5280851979/)