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Publishing and Using Linked Open Data

Richard J. Urban, Ph.D.

School of Library and Information StudiesFlorida State Universityrurban@fsu.edu@musebrarian

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January 7, 2013Monday’s Schedule

• 9:30 - 10:00 Class Session: Participant Introductions

• 10:00- 10:45 Class Session: A Gentle Introduction to Linked Data

• 10:45-11:00 am Break

• 11:00 am- Noon Class Session: Exploring Linked Data Use Cases

• Noon- 1 pm Lunch (on your own)

• 1:00-2:30 pm Class Session: A Gentle Introduction to Linked Data (con't)

• 2:30-2:45 pm Break

• 2:45-3:45pm Class Session: Participant Project Kick-off

• 4:00-5:00 pm Lecture: Seb Chan - Location: Ulrich Recital Hall, Tawes Fine Arts Building

• 5:30 pm-7:00 pm Graduate Student Networking Event Hosted by CUNY and MITH

Location: MITH

0301 Hornbake Library (inside Non-Print Media)

Refreshments Provided

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PARTICIPANT INTRODUCTIONS

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A GENTLE INTRODUCTION TO LINKED DATA: PART I

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A Web of Documents

Berners-Lee, T. (1989) Information Management: A Proposalhttp://goo.gl/xh36K

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World Wide Web

WWW - documents with simple relationships

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An HTML tree

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Document semantics

• XML (and HTML) provides a descriptive markup for documents (including metadata records)

• Even for more complex XML, like TEI, the meaning of many elements is dependent on it’s context within a document instance.

• Interpreting this context requires human intervention.

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Organizing the Web

• Human organization• Crawl and Index

– Uses many of the methods used by digital humanities scholars to extract information from web documents.

• Page Rank– Inferring importance from links

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Database-driven Web:Silos of Data

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Data-driven documents

WWW - documents with simple relationships

Data

Data

Data

Data

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•Federated (Z39.50)

•Aggregated (Open Archives Initiative – Protocol for Metadata Harvesting)

•Application Programming Interface (API) (service specific)

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Data Semantics

• Often dependent on human interpretation of documents/standards.

• Local data-provider interpretations not always documented or available to data consumers.

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LINKED OPEN DATAA New Vision in Two Parts

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Linked Data Principles

1. Use URIs as names for things

2. Use HTTP URIs so that people can look up those names.

3. When someone looks up a URI, provide useful information, using the standards (RDF, SPARQL)

4. Include links to other URIs. so that they can discover more things.

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“Things” = Resources

A resource can be anything that has identity.

Familiar examples include an electronic document, an image, a service (e.g., "today's weather report for Los Angeles"), and a collection of other resources. Not all resources are network "retrievable"; e.g., human beings, corporations, and bound books in a library can also be considered resources.

The resource is the conceptual mapping to an entity or set of entities, not necessarily the entity which corresponds to that mapping at any particular instance in time. Thus, a resource can remain constant even when its content---the entities to which it currently corresponds---changes over time, provided that the conceptual mapping is not changed in the process.

http://www.ietf.org/rfc/rfc2396.txt

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Uniform Resource Identifiers

• More than a Uniform Resource Locator (URL)

• Proves a mechanism to name resources in a way that works at Internet scale.

http://en.wikipedia.org/wiki/Uniform_resource_identifier

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De-referencing URIs

• When someone looks up a URI, provide useful information, using the standards (RDF, SPARQL)

• URIs can be used to name non-networked resources (concepts, people, physical objects, etc.)

• Useful if information about these objects can be returned when the name is used.

• CoolURIs for the Semantic Web http://www.w3.org/TR/cooluris/

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Resource Description Framework

• A model for representing data– An artificial language with a formal semantic

model – Can be expressed using multiple syntaxes– Simple grammar

• RDF “Triple”– <subject> <predicate> <object>– NAME verb Object– Mona Lisa painted by Leonardo da Vinci

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It’s a graph!

• That uses URIs

http://ex.org/monaLisa# http://purl.org/dc/terms/creator/http://ex.org/daVinci#

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From a simple language, we can say complex things.

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RDF Data Modeling

• RDF can be used with multiple tools for modeling data

• Simple: RDF Schema (RDFS)• Robust: Web Ontology Language (OWL)

– OWL-Lite– OWL-Full

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Limitations

• Best used for simple declarative statements– Difficult to express meta-assertions

i.e. “john believes that sally is 5’ tall” – Data provenance/trust– Negation “sally is not 5’ tall” – Tenseless (need to explicitly model time)– Modeling a “record” (named graphs)

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SPARQL

• SPARQL Protocol and RDF Query Language– A query language for RDF– Similar to SQL– Implemented by RDF publication software

(Triplestore)

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Link to Other Resources

• Include links to other URIs. so that they can discover more things.

– Link to controlled vocabularies/ontologies– Use existing RDFS/OWL schemas– link different representations of the same

resources together• Associate annotations with resources

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The Linked Data so far

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Linked Open Data Criteria

★ 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)

★★★ 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

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LINKED DATA USE CASES

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Use Cases

• Linked Library Use Caseshttp://www.w3.org/2005/Incubator/lld/XGR-lld-usecase-20111025/

• DHWI Exampleshttp://www.diigo.com/user/musebrarian/dhwi_example

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A GENTLE INTRODUCTION TO LINKED DATA: PART II

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A Simple Start

• Friend of a Friend (FOAF)http://www.foaf-project.org/

• A simple RDF vocabulary for describing people and their relationships.

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FOAF (Turtle) Syntax

@prefix : <http://xmlns.com/foaf/0.1/> .

<http://chi.cci.fsu.edu/person/rurban#>

:name "Richard J. Urban" ;

:givenname “Richard” ;

:familyname “Urban” ;

:website <http://chi.cci.fsu.edu/> ;

:workplacehomepage <http://slis.fsu.edu> ;

:workplacedirectory <http://directory.cci.fsu.edu/richard-urban/> ;

:publications <http://chi.cci.fsu.edu/person/rurban/publications> ;

:mbox_sha1sum <e122ce3b5475f25d5824e02574806b5e116b2662> ;

:weblog <http://www.inherentvice.net> .

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• http://goo.gl/PgdqN

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FOAF <XML> Syntax

<?xml version="1.0"?>

<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:foaf="http://xmlns.com/foaf/0.1/">

<rdf:Description rdf:about="http://chi.cci.fsu.edu/person/rurban#">

<foaf:name>Richard J. Urban</foaf:name>

<foaf:givenname>Richard</foaf:givenname>

<foaf:familyname>Urban</foaf:familyname>

<foaf:website rdf:resource="http://chi.cci.fsu.edu/" />

<foaf:workplacehomepage rdf:resource="http://slis.fsu.edu" />

<foaf:workplacedirectory rdf:resource="http://directory.cci.fsu.edu/richard-urban/" />

<foaf:publications rdf:resource="http://chi.cci.fsu.edu/person/rurban/publications" />

<foaf:mbox_sha1sum rdf:resource="e122ce3b5475f25d5824e02574806b5e116b2662" />

<foaf:weblog rdf:resource="http://www.inherentvice.net" />

</rdf:Description>

</rdf:RDF>

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Basic Turtle

• Terse RDF Triple Language http://www.w3.org/TeamSubmission/turtle/

• Always start with a @prefix to declare a namespace for each schema you will use in your graph– Can mix/match any published RDF schema

@prefix : <http://xmlns.com/foaf/0.1/> .

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FOAF Propertieshttp://xmlns.com/foaf/spec/

• FOAF Core– Agent– Person– name– title– img– depiction (depicts)– familyName– givenName– knows– based_near– age– made (maker)– primaryTopic (primaryTopicOf)– Project– Organization– Group– member– Document– Image

• Social Web– nick– mbox– homepage– weblog– openid– jabberID– mbox_sha1sum– interest– topic_interest– topic (page)– workplaceHomepage– workInfoHomepage– schoolHomepage

– publications– currentProject– pastProject– account– OnlineAccount– accountName– accountServiceHomepage– PersonalProfileDocument– tipjar– sha1– thumbnail– logo

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Get Yourself a URI

• Can use a CoolURI based on your homepage

• A mailto:email@org.org• A “blank node”

_:me(although these are discouraged for Linked Data)

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@prefix : <http://xmlns.com/foaf/0.1/> .

<http://chi.cci.fsu.edu/person/rurban#>

:name “Richard Urban” ;

:homepage <http://chi.cci.fsu.edu> .

URIs are always enclosed in brackets

Properties start with a colon. Strings are in quotes.

Statements end with a semi-colon…..

Except the last statement ends in a period.

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Hands-on

• Open a text editor.• Write a FOAF description for yourself

using the Turtle Syntax. – http://xmlns.com/foaf/spec/– http://www.w3.org/TeamSubmission/turtle/

• Save the file with .ttl extension– yourName.ttl

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Publishing Your FOAF

• Put the file online, link it from your website.• Publish using an RDF Triplestore• Using FOAF-based plugins for

Wordpress/Drupal, etc.

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Sesame Triple Store

• Let’s use my sandbox for this week:– http://goo.gl/PgdqN

• Select the DHWI repository• Select ADD• Context baseURL: http://chi.cci.fsu/dhwi• Past your Turtle into the RDF box.

• All of us together:

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Linking our FOAF together.

• I know we just met, and this is crazy, but…

:knows <http://chi.cci.fsu.edu/person/rurban#>

• Add the URI of anyone else in the class you know.

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Some FOAF Humanities Use Cases

• Virtual International Authority Filehttp://www.viaf.org

• Social Networks and Archival Contexthttp://socialarchive.iath.virginia.edu/

• Linking Liveshttp://data.archiveshub.ac.uk/page/person/ncarules/skinnerbeverley1938-1999artist

• dbPedia http://dbpedia.org/data/Abraham_Lincoln.n3

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Beyond FOAF

• Organization Ontologyhttp://www.w3.org/TR/vocab-org/

• Encoded Archival Context-Corporate, Personas, Families Ontologyhttp://goo.gl/oFIkW

• Other domain ontologies with representations of people.

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BREAK

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Participant Projects

• What’s a small linked data project you can complete in the next few days?– Explore modeling questions

• Identify existing models

– Create/transform some data • What data is already out there?

– Publish some examples– Explore potential applications

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Tonight’s Events

• 4:00-5:00pm Lecture: Seb Chan– Location: Ulrich Recital Hall in Tawes Fine

Arts Building

• 5:30pm-7:00pm Graduate Student Networking Event– Hosted by CUNY and MITH; Location: MITH,

0301 Hornbake Library inside Non-Print Media

– Refreshments Provided