Introduction to Linked Data

Linked Data Introduction

@sssw2013 - #sssw2013

Data

Linked Data

The Semantic Web

Open University Website

Open UniversityVLE

KMi Website

Mathieu’s Homepage

Mathieu’s List of

PublicationsMathieu’s

Twitter

M366 Coursepage

Person: Mathieu

Publication: Pub1

Organisation:The Open University

Course: M366

Country: Belgium

Book: Mechatronics

author

workFor

availableIn

offers

setBook

The Web of Linked DataThe Web

Basis

• URIs and Web based information access• RDF, graph-based data modelling• SPARQL, querying and updating over web

endpoints

URIsExample:

http://data.open.ac.uk/course/aa100

An anchor for linkingLet’s say you took this course.

You – took this URI

An identifier for a data entity

Here, the a course offered by the Open University

An access point to representation(s) of

the data entityIn possibly different

formats…

RDF – graph data model for the Webhttp://data.open.ac.uk/course/aa100

“The arts past and present”

http://data.open.ac.uk/saou/ontology#undergraduate

http://purl.org/vocab/aiiso/schema#Module

http://data.open.ac.uk/topic/arts_and_humanities

http://sws.geonames.org/3017382/ “France”

dc:title

rdf:label

rdf:type

dc:subject

courseLevel

geo:latgeo:long

RDF+XML<?xml version="1.0" encoding="UTF-8"?>

<rdf:RDF

xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">

<rdf:Description rdf:about="http://data.open.ac.uk/course/aa100">

<title xmlns="http://purl.org/dc/terms/" rdf:datatype="http://www.w3.org/2001/XMLSchema#string">The arts past and present</title>

<courseLevel xmlns="http://data.open.ac.uk/saou/ontology#" rdf:resource="http://data.open.ac.uk/saou/ontology#undergraduate"/>

<isSimilarTo xmlns="http://purl.org/goodrelations/v1#" rdf:resource="http://data.open.ac.uk/course/a200"/>

<hasBook xmlns="http://data.open.ac.uk/saou/ontology#" rdf:resource="http://data.open.ac.uk/book/9780571195473"/>

<location xmlns="http://purl.org/net/mlo/" rdf:resource="http://sws.geonames.org/2634895/"/>

<location xmlns="http://purl.org/net/mlo/" rdf:resource="http://sws.geonames.org/2638360/"/>

<rdf:type rdf:resource="http://purl.org/vocab/aiiso/schema#Module"/>

<assessment xmlns="http://purl.org/net/mlo/" rdf:resource="http://data.open.ac.uk/saou/assessment/end-of-course-assessment"/>

<assessment xmlns="http://purl.org/net/mlo/" rdf:resource="http://data.open.ac.uk/saou/assessment/tma"/>

<subject xmlns="http://purl.org/dc/terms/" rdf:resource="http://data.open.ac.uk/topic/arts_and_humanities"/>

<is-taught-present xmlns="http://courseware.rkbexplorer.com/ontologies/courseware#" rdf:datatype="http://www.w3.org/2001/XMLSchema#boolean">true</is-taught-present>

<taught-at xmlns="http://courseware.rkbexplorer.com/ontologies/courseware#" rdf:resource="http://education.data.gov.uk/id/school/133849"/>

<code xmlns="http://purl.org/vocab/aiiso/schema#" rdf:datatype="http://www.w3.org/2001/XMLSchema#string">AA100</code>

N3<http://data.open.ac.uk/course/aa100> <http://purl.org/dc/terms/title> "The arts past and present"^^<http://www.w3.org/2001/XMLSchema#string> .

<http://data.open.ac.uk/course/aa100> <http://data.open.ac.uk/saou/ontology#OUCourseLevel> "1"^^<http://www.w3.org/2001/XMLSchema#string> . <http://data.open.ac.uk/course/aa100> <http://data.open.ac.uk/saou/ontology#courseLevel> <http://data.open.ac.uk/saou/ontology#undergraduate> .

<http://data.open.ac.uk/course/aa100> <http://purl.org/goodrelations/v1#isSimilarTo> <http://data.open.ac.uk/course/a200> .

<http://data.open.ac.uk/course/aa100> <http://data.open.ac.uk/saou/ontology#hasBook> <http://data.open.ac.uk/book/9780571195473> .

<http://data.open.ac.uk/course/aa100> <http://data.open.ac.uk/saou/ontology#hasBook> <http://data.open.ac.uk/book/9780582817807> .

<http://data.open.ac.uk/course/aa100> <http://purl.org/net/mlo/location> <http://sws.geonames.org/3077311/> .

<http://data.open.ac.uk/course/aa100> <http://purl.org/net/mlo/location> <http://sws.geonames.org/597427/> .

<http://data.open.ac.uk/course/aa100> <http://purl.org/net/mlo/location> <http://sws.geonames.org/2802361/> . <http://data.open.ac.uk/course/aa100> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://purl.org/vocab/aiiso/schema#Module> .

<http://data.open.ac.uk/course/aa100> <http://courseware.rkbexplorer.com/ontologies/courseware#has-title> "The arts past and present"^^<http://www.w3.org/2001/XMLSchema#string> .

<http://data.open.ac.uk/course/aa100> <http://purl.org/net/mlo/assessment> <http://data.open.ac.uk/saou/assessment/end-of-course-assessment> .

<http://data.open.ac.uk/course/aa100> <http://purl.org/net/mlo/assessment> <http://data.open.ac.uk/saou/assessment/tma> .

<http://data.open.ac.uk/course/aa100> <http://purl.org/dc/terms/subject> <http://data.open.ac.uk/topic/classical_studies> .

<http://data.open.ac.uk/course/aa100> <http://purl.org/dc/terms/subject> <http://data.open.ac.uk/topic/arts_and_humanities> .

<http://data.open.ac.uk/course/aa100> <http://purl.org/dc/terms/subject> <http://data.open.ac.uk/topic/english_language> .

SPARQL• ASK query: is this true?ask {<http://data.open.ac.uk/course/aa100> a aiiso:Module} (is it a module?)ask{<http://data.open.ac.uk/course/aa100> dc:subject ?x} (is there a subject to this module?)

• Select query: Get me some dataselect ?book ?title where { ?x a aiiso:Module. ?x dc:subject <http://data.open.ac.uk/topic/Music>. ?x courseware:setBook ?book. ?book dc:title ?title filter( ?x != <http://data.open.ac.uk/course/aa100> ) } order by ?title limit 100(get the books associated with courses in music which are not AA100)

• Construct query: Build a (sub) RDF graphconstruct {?agent1 foaf:knows ?agent2} where s{?x bibo:creator ?agent1. ?x bibo:creator ?agent2}(Construct of graph of people knowing each-other because of being co-authors of at least one thing)

SPARQL is also a protocol for Web-based data endpoints…

Example

select distinct ?course where {?course <http://data.open.ac.uk/saou/ontology#isAvailableIn> <http://sws.geonames.org/2328926/>.?course a <http://purl.org/vocab/aiiso/schema#Module>}

Open University courses available in Nigeria (http://sws.geonames.org/2328926/)on http://data.open.ac.uk/query

Exampleselect distinct ?q (count(distinct ?t) as ?n) where { ?q a <http://purl.org/net/mlo/qualification>. ?q <http://data.open.ac.uk/saou/ontology#hasPathway> ?p. ?p <http://data.open.ac.uk/saou/ontology#hasStage> ?s. {{?s <http://data.open.ac.uk/saou/ontology#includesCompulsoryCourse> ?c} union {?s <http://data.open.ac.uk/saou/ontology#includesOptionalCourse> ?c}}. ?c <http://purl.org/dc/terms/subject> ?t. [] <http://www.w3.org/2004/02/skos/core#hasTopConcept> ?t.} group by ?q order by desc(?n)

How many top level subjects are represented in individual Open University qualifications on http://data.open.ac.uk/query

Exampleselect ?broader ?term ?narrowerwhere { graph npgg:subjects { ?subject skos:prefLabel ?term . ?subject skos:broader [ skos:prefLabel ?broader ] . ?_ skos:broader ?subject ; skos:prefLabel ?narrower . } filter(regex(?term, "^Stem cells$", "i"))}order by ?broader ?narrower

Broader and narrower terms for "Stem cells“ on http://data.nature.com/query

Exampleselect ?doi ?datawhere { ?doi a npg:Article ; npg:hasDataCitation [ npg:hasLink [ ?_ ?data ] ; npg:type ?type ] . filter(regex(?type, "pdb"))}limit 25

Data citations to the Protein Database on http://data.nature.com/query

SPARQL updateDelete querydelete {?x ?p ?y} where { ?x a aiiso:Course. ?x ?p ?y. ?a1 aiiso:responsibleFor ?x. ?a2 aiiso:responsibleFor ?x. filter ( ?a1 != ?a2 )}

Insert query insert {?x a onto:WeirdCourse} where{ ?x a aiiso:Course. ?a1 aiiso:responsibleFor ?x. ?a2 aiiso:responsibleFor ?x. filter ( ?a1 != ?a2 )}

What we will during the hands-on session

• Access URIs to get data in different forms – understand how the HTTP protocol is used to access data

• Inspect RDF representations of objects – follow links to others

• Write SPARQL query to retrieve specific information• Create new data with SPARQL update – think about how

to model the data with RDF

Hands-on session