Short introduction to how the City of Ghent uses and publishes Linked Open Data, with examples and exercises! :)

1. Linked Data Sandwich
Stad Gent
19 Oktober
E-Gebouw
image: beeldbank.stad.gent
Thimo Thoeye
Stad Gent
thimo.thoeye@stad.gent
@tthoeye

2. Wat zit er in onze website?

3. Diensten
Wat zit er in onze website?

4. Diensten
Nieuwsberichten
Wat zit er in onze website?

5. Diensten
Nieuwsberichten
Wat zit er in onze website?
Evenementen

6. Diensten
Nieuwsberichten
Wat zit er in onze website?
Evenementen
...

7. Waar komt deze vandaan?

8. Waar gaat ze naartoe?

9. Open Data

10. Linked Open Data

11. Wat Linked Open Data?

12. image: 5stardata.info

13. “it gives me a headache just trying to think
down to your level”
image: io9.com

14. The Semantic Web
A new form of Web content that is meaningful to computers will unleash a
revolution of new possibilities
by TIM BERNERS-LEE, JAMES HENDLER and ORA LASSILA
Scientifc American, May 2001
http://www-sop.inria.fr/acacia/cours/essi2006/Scientific%20American_%20Feature%20Article_%20The%20Semantic%20Web_%20May%202001.pdf

15. 1. Use URIs to name (identify) things.
2. Use HTTP URIs so that these things can be looked up
(interpreted, "dereferenced").
3. Provide useful information about what a name identifies when it's
looked up, using open standards such as RDF, SPARQL, etc.
4. Refer to other things using their HTTP URI-based names when
publishing data on the Web.

16. Gebruik van URI’s
Tom

17. Gebruik van URI’s
Tom Tom Tom

18. Gebruik van URI’s
12 34 12

19. Gebruik van URI’s
http://es-la.dbpedia.org/page/resourc
e/Tom_Selleck
https://www.facebook.com/tom.
vannieuwenhove.1
http://dbpedia.org/resource/To
m_and_Jerry

20. Triples
Tom is a Cat

21. Triples
Tom is a http://dbpedia.org/page/Cat

22. Triples
http://www.facebook.com/tom
is a
http://dbpedia.org/page/Cat

23. Triples
http://www.facebook.com/tom
https://www.w3.org/1999/02/22-rdf-syntax-ns#type
http://dbpedia.org/page/Cat

24. Triples
http://www.facebook.com/tom
https://www.w3.org/1999/02/22-rdf-syntax-ns#type
http://dbpedia.org/page/Cat
Subject
Predicate
Object

25. Triples
http://www.facebook.com/tom
https://www.w3.org/1999/02/22-rdf-syntax-ns#type
http://dbpedia.org/page/Cat
Resource
Property
Class

26. Triples
facebook:tom rdf:type dbpedia:cat
Subject Predicate Object

27. Triples
facebook:tom rdf:type dbpedia:cat

28. Graph

29. Triples
Tom is a Cat
Tom is a Dog

30. Named Graph

31. Quad
Subject Predicate Object Graphname

32. Organising it
RDF Schema
https://www.w3.org/TR/rdf-schema/
OWL
https://www.w3.org/TR/owl-features/
SKOS
https://www.w3.org/TR/skos-reference/

33. Organising it
Ontologies
FOAF: http://xmlns.com/foaf/spec/
GeoNames: http://www.geonames.org/ontology/documentation.html
Dublin Core: http://dublincore.org/documents/dcmi-terms/
Schema: http://schema.org

34. Organising it
http://lov.okfn.org

35. Representing it
https://stad.gent/id/news/25259
<?xml version="1.0" encoding="utf-8" ?>
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:schema="http://schema.org/"
xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
xmlns:dc="http://purl.org/dc/terms/"
xmlns:foaf="http://xmlns.com/foaf/0.1/">
<schema:NewsArticle rdf:about="https://stad.gent/id/news/25259">
<rdfs:isDefinedBy rdf:resource="https://stad.gent/data/news/25259"/>
<schema:datePublished>2014-10-23T09:55:44+02:00</schema:datePublished>
<schema:articleBody>De fiets is een populair vervoersmiddel in Gent...</schema:articleBody>
<schema:description>Politie en Stad Gent maken fietsers attent op ...</schema:description>
<schema:headline>Campagne goede fietsverlichting</schema:headline>
<dc:identifier>25259</dc:identifier>
<foaf:page rdf:resource="https://stad.gent/node/25259"/>
</schema:NewsArticle>
</rdf:RDF>
RDF+XML

36. Representing it
https://stad.gent/id/news/25259
@prefix schema: <http://schema.org/> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix dc: <http://purl.org/dc/terms/> .
@prefix foaf: <http://xmlns.com/foaf/0.1/> .
<https://stad.gent/id/news/25259>
a schema:NewsArticle ;
rdfs:isDefinedBy <https://stad.gent/data/news/25259> ;
schema:datePublished "2014-10-23T09:55:44+02:00" ;
schema:articleBody "De fiets is een populair vervoersmiddel in Gent..." ;
schema:description "Politie en Stad Gent maken fietsers attent op ..." ;
schema:headline "Campagne goede fietsverlichting" ;
dc:identifier "25259" ;
foaf:page <https://stad.gent/node/25259> .
Turtle

37. Representing it
https://stad.gent/id/news/25259
[{"@id":"http://schema.org/NewsArticle"},{"@id":"https://stad.gent/data/news/25259"},{"@id":"https://s
tad.gent/id/news/25259","@type":["http://schema.org/NewsArticle"],"http://www.w3.org/2000/01/rdf-schem
a#isDefinedBy":[{"@id":"https://stad.gent/data/news/25259"}],"http://schema.org/datePublished":[{"@val
ue":"2014-10-23T09:55:44+02:00"}],"http://schema.org/articleBody":[{"@value":"De fiets is een populair
vervoersmiddel in Gent..."}],"http://schema.org/description":[{"@value":"Politie en Stad Gent maken
fietsers attent op ..."}],"http://schema.org/headline":[{"@value":"Campagne goede
fietsverlichting"}],"http://purl.org/dc/terms/identifier":[{"@value":"25259"}],"http://xmlns.com/foaf/
0.1/page":[{"@id":"https://stad.gent/node/25259"}]},{"@id":"https://stad.gent/node/25259"}]
JSON-LD

38. Ontologies and Vocabularies used in http://stad.gent
schema.org
OSLO
Core Public Service
Core Location
Core Business
Core Person

39. Architectuur
Header: Content-type: text/html
F5

40. Architectuur
Header: Accept: text/html
F5

41. Architectuur
Header: Accept: application/rdf+xml
F5

42. Architectuur
Header: Accept: application/rdf+xml
F5

43. Show me the data!
SPARQL Endpoint:
News items:
Products:
Manuals:
http://stad.gent/sparql
http://stad.gent/data/news/
http://stad.gent/data/products/
https://stad.gent/over-gent-en-het-stadsbestuur/ov
er-gent/kaarten-cijfers-en-data/linked-open-data

44. SPARQL

45. http://stad.gent/sparql
http://linkedgeodata.org/sparql
http://dbpedia.org/sparql
...

46. http://stad.gent/sparql
http://linkedgeodata.org/sparql
http://dbpedia.org/sparql
...

47. Examples
All places of Ghent
SELECT ?Thing
WHERE { ?Thing a <http://schema.org/Place> }
result

48. Examples
All places of Ghent
SELECT ?Thing
WHERE { ?Thing a <http://schema.org/Place> } LIMIT 100
Using LIMIT
result

49. Examples
All districts of Ghent
SELECT DISTINCT ?Thing
WHERE {
?Thing a <http://schema.org/Place> .
?Thing <https://stad.gent/data/internal/resourceType>
"wijken"^^<http://www.w3.org/2001/XMLSchema#string> .
} LIMIT 100
result

50. Examples
All districts of Ghent
PREFIX schema: <http://schema.org/>
PREFIX gent: <https://stad.gent/data/internal/>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
SELECT ?Thing
WHERE {
?Thing a schema:Place .
?Thing gent:resourceType "wijken"^^xsd:string .
} LIMIT 100
Using PREFIX
result

51. Examples
All districts of Ghent
PREFIX schema: <http://schema.org/>
PREFIX gent: <https://stad.gent/data/internal/>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
SELECT DISTINCT ?Thing
WHERE {
?Thing a schema:Place .
?Thing gent:resourceType "wijken"^^xsd:string .
} LIMIT 100
Using DISTINCT
result

52. Examples
All districts of Ghent
PREFIX schema: <http://schema.org/>
PREFIX gent: <http://stad.gent/data/internal/>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
SELECT count(DISTINCT ?Thing) as ?aantal
WHERE {
?Thing a schema:Place .
?Thing gent:resourceType "wijken"^^xsd:string .
}
Using COUNT
result

53. Examples
All districts of Ghent
PREFIX schema: <http://schema.org/>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
PREFIX gent: <https://stad.gent/data/internal/>
SELECT DISTINCT ?place ?name
WHERE {
?place a schema:Place .
?place schema:name ?name .
?place gent:resourceType "wijken"^^xsd:string .
} LIMIT 100
By name
result

54. Examples
All news articles for district
“Sluizeken”
SELECT DISTINCT ?a WHERE {
?a a <http://schema.org/NewsArticle>.
?a <http://schema.org/contentLocation> <https://stad.gent/id/places/wijken--2> .
}
result

55. Examples
Products for ecological
companies:
PREFIX schema: <http://schema.org/>
PREFIX dct:<http://purl.org/dc/terms/>
SELECT ?product ?titel
WHERE {
?product a <http://purl.org/vocab/cpsv#PublicService>.
?product schema:audience <http://stad.gent/data/ns/gpdc/doelgroepen/onderneming>.
?product dct:subject <http://stad.gent/data/ns/themas/natuur-milieu>.
?product dct:title ?titel
}
result

56. Examples
Most popular books among men in Ledeberg in 2010
PREFIX schema: <http://schema.org/>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX service: <http://purl.org/ontology/service#>
select ?book (sample(?name) as ?naam) (COUNT(?person) as ?aantal_personen)
FROM <http://stad.gent/dekrook/uitleningen-2010>
FROM <http://stad.gent/dekrook/exemplaren>
FROM <http://stad.gent/dekrook/werken>
WHERE {
?offer a schema:Offer.
?book schema:offers ?offer.
?book schema:name ?name.
?person a schema:Person;
service:consumes ?offer;
schema:gender "Mannelijk";
schema:address "9050".
} GROUP BY ?book ORDER BY DESC(?aantal_personen) LIMIT 10
result

57. Links
http://data.stad.gent
http://stad.gent/sparql
http://data.vlaanderen.be
https://stad.gent/over-gent-en-het-stadsbestuur/over-gent/kaarten-cijf
ers-en-data/linked-open-data
http://oasis.team
thimo.thoeye@stad.gent

58. Exercises

59. SKOS
https://www.w3.org/2009/08/skos-reference/skos.html#
● skos:Collection
○ skos:OrderedCollection
● skos:Concept
● skos:ConceptScheme
○ skos:inScheme
○ skos:hasTopConcept
○ skos:topConceptOf
● skos:prefLabel
○ skos:altLabel
○ skos:note
○ skos:historyNote
● skos:semanticRelation
○ skos:mappingRelation
○ skos:closeMatch
○ skos:exactMatch
○ skos:broadMatch
○ skos:narrowMatch
○ skos:relatedMatch

60. SKOS: Example
Theme list
PREFIX skos:<http://www.w3.org/2004/02/skos/core#>
SELECT ?thema
WHERE {
?thema skos:inScheme <http://stad.gent/data/ns/themas/>
}
result

61. Examples
Recent news items related to
museums SMAK en Huis van Alijn
PREFIX schema:<http://schema.org/>
SELECT ?article ?titel ?published
WHERE {
VALUES ?org {
<https://stad.gent/id/agents/96677ab3-f689-e111-a140-0050569826fc>
<https://stad.gent/id/agents/ad7ccf21-61d8-e411-87b3-005056983224>
}.
?article a schema:NewsArticle.
?article schema:datePublished ?published.
?article <http://schema.org/sourceOrganization> ?org.
?article schema:headline ?titel
} ORDER BY DESC(?published) LIMIT 5
result

62. Examples
Hoeveel nieuwsberichten zijn er gepubliceerd in januari 2017?
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX schema: <http://schema.org/>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
SELECT (count(?sub) as ?articles) WHERE {
?sub a <http://schema.org/NewsArticle>;
schema:datePublished ?date.
BIND(YEAR(STRDT(?date, xsd:dateTime)) as ?year)
BIND(MONTH(STRDT(?date, xsd:dateTime)) as ?month)
FILTER(?year = 2017)
FILTER(?month = 1)
}
result

63. Examples
Uitleningen in maart 2017
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
SELECT count(?sub) from <http://stad.gent/dekrook> WHERE {
?sub a <http://purl.org/ontology/dso#Loan>.
?sub <http://schema.org/startDate> ?start.
?sub <http://purl.org/ontology/service#consumes> ?book.
FILTER ( STRDT(STR(?start),xsd:dateTime) < xsd:dateTime("2017-04-01T00:00:00Z") )
FILTER ( STRDT(STR(?start),xsd:dateTime) > xsd:dateTime("2017-03-01T00:00:00Z") )
}
result

64. Examples
De tien meest uitgeleende boeken
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX schema: <http://schema.org/>
SELECT ?book (COUNT(?sub) as ?uitleningen) from <http://stad.gent/dekrook> WHERE {
?sub a <http://purl.org/ontology/dso#Loan>.
?sub <http://schema.org/startDate> ?start.
?sub <http://purl.org/ontology/service#consumes> ?offer.
?book schema:offers ?offer.
} GROUP BY ?book ORDER BY DESC(?uitleningen) LIMIT 10
result

65. Examples
Boeken gepubliceerd in 2001
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
SELECT ?sub ?date from <http://stad.gent/dekrook> WHERE {
?sub a <http://schema.org/Book> .
?sub <http://schema.org/datePublished> ?date.
filter(?date = "2001")
} limit 40
result