2. AGENDA
• What is Linked Data?
• How can I query Linked Data?
• How to create visualizations using Visualbox
3. WHAT IS LINKED DATA?
• Linked Data is a way to
publish data in a machine-
readable way
• Itallows you to describe
information about things on
the Web and their
relationships
• Government, NGOs and
universities publish Linked
Data
4. WHAT IS LINKED DATA?
• Example:
• London is the capital of England.
• London’s population is 8 million people
• England is a Country.
5. WHAT IS LINKED DATA?
England is a
capital of
Country
London
population
8.000.000
• England is a Country.
• England ‘s capital is London.
• London’s population is 8 million people
6. ON THE WEB...
• We create a URI (i.e., “web address”-like identifier) for everything
• London → http://dbpedia.org/resource/London
• England → http://dbpedia.org/resource/England
• Country → http://dbpedia.org/ontology/Country
• Same for relations!
• capital of → http://dbpedia.org/ontology/capital
• is a → http://www.w3.org/1999/02/22-rdf-syntax-ns#type
• population → http://dbpedia.org/ontology/populationUrban
7. LINKED DATA
England is a
capital of
Country
London
population
8.000.000
http://dbpedia.org/resource/England
http://dbpedia.org/ontology/capital http://www.w3.org/1999/02/22-rdf-syntax-ns#type
http://dbpedia.org/resource/London
http://dbpedia.org/ontology/populationUrban
http://dbpedia.org/ontology/Country
8.000.000
8. HOW CAN I QUERY
LINKED DATA?
• We can use SPARQL, a query language for Linked Data
• People
(and governments) publishes Linked Data in SPARQL
endpoints that can be queried
11. SCHOOLS IN THE CITY OF
LONDON
PREFIX sch-ont: <http://education.data.gov.uk/def/school/>
PREFIX geo: <http://www.w3.org/2003/01/geo/wgs84_pos#>
PREFIX district: <http://statistics.data.gov.uk/id/local-authority-district/>
SELECT ?school ?name ?lat ?long WHERE {
?school a sch-ont:School;
sch-ont:establishmentName ?name;
geo:lat ?lat;
geo:long ?long;
sch-ont:districtAdministrative district:00AA .
}
ORDER BY ?name
12. RESULTS
Executed against
http://education.data.gov.uk/sparql/education/query
school name lat long
http://education.data.gov.uk/id/school/581261 Barbican Playgroup 51.51879 -0.09267
Buffer Bear @ Barts &
http://education.data.gov.uk/id/school/531003 51.51697 -0.10086
the London
Charterhouse Square
http://education.data.gov.uk/id/school/590270 51.52038 -0.09886
School