Lifting the Lid on Linked Data

Linked Data and the LOCAH project Jane Stevenson & Adrian Stevenson

Linked Data on the Hub & Copac Linked Open Copac and Archives Hub: Locah JISC funded project August 2010 – July 2011 Mimas UKOLN Eduserv

The goal of Linked Data is to enable people to share structured data on the Web as easily as they can share documents today. It is a space where people and organizations can post and consume data about anything. Bizer/Cyganiak/Heath Linked Data Tuturial, linkeddata.org

Core questions
Is it achievable?
Will it bring substantial benefits?
“ It is the unexpected re-use of information which is the value added by the web”

What is Linked Data?
4 ‘ rules ’ of for the web of data:
Use URIs as names for things
Use HTTP URIs so that people can look up those names.
When someone looks up a URI, provide useful information, using the standards (RDF, SPARQL)
Include links to other URIs. so that they can discover more things.
http://www.w3.org/DesignIssues/LinkedData.html

Use URIs as Names
We can make statements about things and establish relationships by assigning identifiers to them.
Uniform Resource Identifiers (URIs) are identifiers for entities (people, places, subjects, records, institutions).
They identify resources , and ideally allow you to access representations of those resources.
author = http://archiveshub.ac.uk/janefoaf.rdf book = http://dbpedia.org/resource/manchester subject = English = http://lexvo.org/id/iso639-3/eng

Entities and Relationships

ProvidesAccessTo Subject: Bibliographic Resource Predicate: AccessProvidedBy Object: Library Subject > Predicate > Object AccessProvidedBy Triple statement Bibliographic Resource Library

describedBy heldAt encodedAs has An RDF Graph Bibliographic Resource Library Bibliographic Record MODS document Title

So...?
If something is identified, it can be linked to
We can then t ake items from one dataset and link them to items from other datasets
BBC VIAF DBPedia Archives Hub Copac GeoNames

The Linking benefits of Linked Data BBC:Cranford VIAF:Gaskell DBPedia: Gaskell Hub:Gaskell Copac:Cranford Geonames:Manchester DBPedia: Dickens Hub:Dickens

The Web of ‘ Documents ’
Global information space (for humans)
Document paradigm
Hyperlinks
Search engines index and infering relevance
Implicit relationships between documents
Lack of semantics

The Web of Linked Data
Global data space (for humans and machines)
Making connections between entities across domains (people, books, films, music, genes, medicines, health, statistics...)
LD is not about searching for specific documents or visiting particular websites, it is about things - identifying and connecting them.

Copac model
Groundwork done with Archives Hub. Then had to decide what we wanted to say about the data
Challenges over what a ‘record’ is – ‘Bleak House’ from each contributor? or one merged record?
In many ways simpler than archival data; but also can decide to create a simpler model

Copac Model (as at November 2010)

Copac specification
Model = entities and relationships
Specification = means to specify these more exactly – programmer can create transform script
Iterative process – model – spec – RDF output

Cardinality Property URI/literal 1 1 dct:title literal 0 1 dct:extent literal 0 m bibo:isbn literal 0 m bibo:issn literal 0 m bibo:note literal 0 m dct:alternative literal 0 m copac:uniformtitle literal Node name MODS field Ontology BibliographicResource <modscollection> bibo

Node name MODS field Ontology BibliographicResource <modscollection> bibo cardinality property URI/literal ontology 0 1 copac:creator Creator URI dc 0 m copac:contributor Contributor URI coapc 0 1 event:producedIn Production Date URI event 0 1 dct:issued Production Date URI dc 0 m pode:publicationPlace Place URI pode 0 m isbd:P1016 Place URI isbd 0 m dct:publisher Publisher URI dc 0 1 dct:isPartOf Series URI dc 1 m copac:HeldBy Institution URI with Institution as subject 1 1 bibo:type Type URI bibo 0 m dct:subject Subject URI dc 0 m skos:subject subject URI skos 0 m dct:language Language URI dc 1 1 hub:encodedAs mods URI hub

cardinality property URI/literal URI 1 1 rdf:type URIs http://purl.org/dc/terms/Agenthttp://xmlns.com/foaf/0.1/Agent 1 1 rdfs:label literal {namePart} 1 1 skos:prefLabel literal {namePart} 1 1 isCreatorOf Bibliographic Resource URI root/id/bibliographicresource/{recordIdentifer} Node name MODS field URI namespace uri pattern Creator <name> <namePart></namePart>where <roleTerm>creator</roleTerm> copac root/id/agent/{BibID}{namePart}

Aggregated Data

Aggregated data
Copac MODS record = an aggregated book record
e.g. ‘Bleak House’ held at 10 different libraries
Copac ‘merges’ the descriptions from 8 of them
2 are not consistent with the rest, so they remain as stand-alone descriptions
End result: have 3 records for ‘Bleak House’
Not talking about ‘a book’

Copac decisions
Vocabularies:
dcterms:creator
dcterms:contributor
copac:heldBy
When to create URIs
Title = literal
Publication place = URI
How to deal with problematic/ambiguous data
Date? = productionDate

‘ Creator’
Copac ‘creator’ = author or editor
<copac:creator> <dcterms:creator> <biblioResource>
Alternative name = dct:alternative
Uniform name = copac:uniform
6957115KNAPPF 6947115 <isCreatorOf>

‘ Contributor’
Contributor = editor, illustrator, translator
Cannot specify role – has to be general
<dcterms:contributor>

RDF Process

What is LOCAH doing?
Part 1: Exposing the Linked Data
Part 2: Creating a prototype visualisation
Part 3: Reporting on opportunities and barriers

How are we exposing the Data?
Model our ‘things’ into RDF
Transform the existing data into RDF/XML
Enhance the data
Load the RDF/XML into a triple store
Create Linked Data Views
Document the process, opportunities and barriers on LOCAH Blog

1. Modelling ‘things’ into RDF
Hub data in ‘Encoded Archival Description’ EAD XML form
Copac data in ‘Metadata Object Description Schema’ MODS XML form
Take a step back from the data format
Think about your ‘things’
What is EAD document “saying” about “things in the world”?
What questions do we want to answer about those “things”?
http://www.loc.gov/ead/ http://www.loc.gov/standards/mods/

Need to decide on patterns for URIs we generate
Following guidance from W3C ‘ Cool URIs for the Semantic Web ’ and UK Cabinet Office ‘ Designing URI Sets for the UK Public Sector ’
http://data.archiveshub.ac.uk/ id /findingaid/gb1086skinner ‘thing’ URI
… is HTTP 303 ‘See Other’ redirected to …
http://data.archiveshub.ac.uk/ doc /findingaid/gb1086skinner document URI
… which is then content negotiated to …
http://data.archiveshub.ac.uk/doc/findingaid/gb1086skinner .html http://data.archiveshub.ac.uk/doc/findingaid/gb1086skinner .rdf http://data.archiveshub.ac.uk/doc/findingaid/gb1086skinner .turtle http://data.archiveshub.ac.uk/doc/findingaid/gb1086skinner .json
http://www.w3.org/TR/cooluris/ http://www.cabinetoffice.gov.uk/resource-library/designing-uri-sets-uk-public-sector

Using existing RDF vocabularies:
DC, SKOS, FOAF, BIBO, WGS84 Geo, Lexvo, ORE, LODE, Event and Time Ontologies
Define additional RDF terms where required,
copac:BibiographicResource
copac:Creator
It can be hard to know where to look for vocabs and ontologies
Decide on licence – CC BY-NC 2.0, CC0, ODC PDD

Vocabularies in Linked Data
Common vocabularies to describe the data, e.g. ‘ title ’ ‘ author ’ ‘ contributor ’ mean the same thing
Adopt the same vocabularies for expressing meaning
Use semantics to link data
Want to avoid transformation, mapping, contracts between data providers

Commonly used vocabularies (ones we’ve used in bold)
Friend-of-a-Friend (FOAF) , vocabulary for describing people.
Dublin Core (DC) defines general metadata attributes. See also their new domains and ranges draft .
Semantically-Interlinked Online Communities (SIOC) , vocabulary for representing online communities.
Description of a Project (DOAP) , vocabulary for describing projects.
Simple Knowledge Organization System (SKOS) , vocabulary for representing taxonomies and loosely structured knowledge.
Music Ontology provides terms for describing artists, albums and tracks.
Review Vocabulary , vocabulary for representing reviews.
Creative Commons (CC) , vocabulary for describing license terms.
Bibo, vocabulary for bibliographic data

Copac RDF DC foaf skos Copac bibo dcterms:title dcterms:identifier Shared use of vocabularies Hub RDF DC foaf skos Hub

2. Transforming in RDF/XML
Transform EAD and MODS to RDF/XML based on our models
Hub: created XSLT Stylesheet and used Saxon parser
http://saxon.sourceforge.net/
Saxon runs the XSLT against a set of EAD files and creates a set of RDF/XML files
Copac: created in-house Java transformation program

3. Enhancing our data
Language - lexvo.org
Time periods - reference.data.gov.uk
Geolocation - UK Postcodes URIs and Ordnance Survey URIs
Names - Virtual International Authority File
Matches and links widely-used authority files - http://viaf.org/
Names (and subjects) - DBPedia
Subjects - Library of Congress Subject Headings

Use of ‘SameAs’
<sameAs>
Estelle Sylvia Pankhurst, 1882-1960: http://archiveshub.ac.uk/data/gb-106-7esp http://viaf.org/viaf/51731588/
John William Bradley, fl. 1874: http://archiveshub.ac.uk/data/gb0096ms415 http://viaf.org/viaf/61047183/

4. Load RDF/XML into triple store
Using the Talis Platform triple store
RDF/XML is HTTP POSTed
We’re using Pynappl
Python client for the Talis Platform
http://code.google.com/p/pynappl/
Store provides us with a SPARQL query interface

5. Create Linked Data Views
Expose ‘bounded’ descriptions from the triple store over the Web
Make available as documents in both human-readable HTML and RDF formats (also JSON, Turtle, CSV)
Using Paget ‘Linked Data Publishing Framework’
http://code.google.com/p/paget/
PHP scripts query Sparql endpoint

http://data.archiveshub.ac.uk/id/archivalresource/gb1086skinner

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

Accessing the Locah Linked Data
Hub data released
Copac data release imminent
Include Linked Data views, Sparql endpoint details, example queries and supporting documentation

Reporting on opportunities and barriers
Locah Blog (tags: ‘opportunities’ ‘barriers’)
Feed into #JiscEXPO programme evidence gathering
More at:
http://blogs.ukoln.ac.uk/locah/2010/09/22/creating-linked-data-more-reflections-from-the-coal-face/
http://blogs.ukoln.ac.uk/locah/2010/12/01/assessing-linked-data

Feedback Requested!
We would like feedback on the project
Via blog
http://blogs.ukoln.ac.uk/locah/2010/09/28/model-a-first-cut/
http://blogs.ukoln.ac.uk/locah/2010/11/08/some-more-things-some-extensions-to-the-hub-model/
http://blogs.ukoln.ac.uk/locah/2010/10/07/modelling-copac-data/
Via email, twitter, in person

Creating a Visualisation Prototype
Currently working on Hub visualisation
Data queried from Sparql endpoint
Use tools such as Simile, Many Eyes, Google Charts
Timemap visualisation
Googlemaps and Simile
http://code.google.com/p/timemap/

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://socialarchive.iath.virginia.edu/prototype.html

The learning process
Model the data, not the description
The description is one of the entities
Understand the importance of URIs
Think about your world before others
… but external links are important
Try to get to grips with terminology
Be prepared for unexpected surprises!

Risks
Can you rely on data sources long-term?
Persistence of persistent URIs?
New technologies
Investment of time – unsure of benefits
Licensing issues

Licensing
Nature of Linked Data: each triple as a piece of data
‘ Ownership’ of data?
Data often already freely available (M2M interfaces)

Licensing
Public Domain Licences: simple, explicit, and permit widest possible reuse. Waive all rights to the data
BL, British National Bibiography uses public domain licence
Limit commercial uses?
Build in community norms: attribution, share alike - to reinforce desire for acknowledgement
Legal situation?

Thank You

Sections of this presentation adapted from materials created by other members of the LOCAH Project This presentation available under creative commons Non Commercial-Share Alike: http://creativecommons.org/licenses/by-nc/2.0/uk/ Attribution and CC licence

http://blogs.ukoln.ac.uk	4217
http://archiveshub.ac.uk	983
url_unknown	16
http://translate.googleusercontent.com	11
http://www.newsblur.com	5
http://locahproject.wordpress.com	5
http://webcache.googleusercontent.com	3
http://twitter.com	1
http://www.twylah.com	1

Lifting the Lid on Linked Data

by Jane Stevenson

Accessibility

Categories

Upload Details

Usage Rights

9 Embeds 5,242

Statistics