1. RDF
principles and case studies
Diego Valerio Camarda
regesta.exe
www.regesta.com
diego.camarda@regesta.com
dvcama @ github&twitter

2. a brief
introduction to
linked open data

3. why things
instead of documents
Html
page
Html
pageHtml
page
Html
pageHtml
page
The nowadays WEB

4. why things
instead of documents
The nowadays WEB
at least 1.85 billion indexed documents
someone says 1 trillion online documents
Html
page
Html
pageHtml
page
Html
pageHtml
page

5. why things
instead of documents
The nowadays WEB
at least 1.85 billion indexed documents
someone says 1 trillion online documents
actually the best HTML parser is still the HUMAN BRAIN
Html
page
Html
pageHtml
page
Html
pageHtml
page

6. why things
instead of documents
The nowadays WEB
is not the WEB that
Tim proposed in 1998

7. why things
instead of documents
The nowadays WEB
is not the WEB that
Tim proposed in 1998

8. why things
instead of documents
The nowadays WEB
is not the WEB that
Tim proposed in 1998

9. what about URIs and RDF
a new way to publish data on the web
ids are ambiguous and suck!
Use URIs
as names for things
Use HTTP URIs
so that people can look up those names
Use the standards (RDF, SPARQL)
providing useful information
Include links to other URIs
so that they can discover more things
linked data principles
Tim Berners-Lee
July 27, 2006

10. HTTP://yourdomain.com/something
what about URIs and RDF
turning web pages in “real” data
ids are ambiguous and suck!

11. what about URIs and RDF
turning web pages in “real” data
ids are ambiguous and suck!

12. […] l’animaletto venne indicato come:
“il tasso del tasso del Tasso”
Achille Campanile
It’s time for machine
(for parsing pages)

13. […] l’animaletto venne indicato come:
“il tasso del tasso del Tasso”
Achille Campanile
It’s time for machine
(for parsing pages)
http://it.dbpedia.org/resource/Meles_meles
http://it.dbpedia.org/resource/Taxus
http://it.dbpedia.org/resource/Torquato_Tasso
http://it.dbpedia.org/resource/Achille_Campanile
(author of the sentence)

14. A new way to design
databases
RDF
(aka ’define knowledge’)

15. Go Triples, go!
the standard (old) approach
ID_P COGNOME NOME REF_ID_SOCIETA GENERE
1 Camarda Diego 1 maschio
2 … … … …
ID_SOCIETA DENOMINAZIONE SITO
1 Regesta.exe srl www.regesta.com

16. Go Triples, go!
the new (cool) approach
<http://www.regesta.com/diego>Subject

17. Go Triples, go!
the new (cool) approach
<http://www.regesta.com/diego>
<http://xmlns.com/foaf/0.1/familyName>
Subject
Predicate

18. Go Triples, go!
the new (cool) approach
<http://www.regesta.com/diego>
<http://xmlns.com/foaf/0.1/familyName>
‘Camarda’.
Subject
Predicate
Object

19. Go Triples, go!
the new (cool) approach
<http://www.regesta.com/diego>
<http://xmlns.com/foaf/0.1/familyName> ‘Camarda’.
<http://www.regesta.com/diego>
<http://xmlns.com/foaf/0.1/firstName> ‘Diego’.
<http://www.regesta.com/diego>
<http://xmlns.com/foaf/0.1/gender> ‘male’.

20. Go Triples, go!
the new (cool) approach
<http://www.regesta.com/diego>
<http://xmlns.com/foaf/0.1/familyName> ‘Camarda’ ;
<http://xmlns.com/foaf/0.1/firstName> ‘Diego’ ;
<http://xmlns.com/foaf/0.1/gender> ‘male’ .

21. Go Triples, go!
ok, but what a “diego” is?

22. Go Triples, go!
it’s a person!
<http://www.regesta.com/diego> a <http://xmlns.com/foaf/0.1/Person>

23. Go Triples, go!
adding a Class
<http://www.regesta.com/diego>
<http://xmlns.com/foaf/0.1/familyName> ‘Camarda’ ;
<http://xmlns.com/foaf/0.1/firstName> ‘Diego’ ;
<http://xmlns.com/foaf/0.1/gender> ‘male’ .
<http://www.regesta.com/diego>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<http://xmlns.com/foaf/0.1/Person> .

24. Go Triples, go!
building a graph
<http://www.regesta.com/diego>
<http://xmlns.com/foaf/0.1/familyName> ‘Camarda’ ;
<http://xmlns.com/foaf/0.1/firstName> ‘Diego’ ;
<http://xmlns.com/foaf/0.1/gender> ‘male’ ;
<http://www.w3.org/1999/...#type> <http://xmlns.com/foaf/0.1/Person> .
<http://www.regesta.com/diego>
<http://www.w3.org/ns/org#memberOf>
<http://www.regesta.com/about> .

25. Go Triples, go!
building a graph
<http://www.regesta.com/diego>
<http://xmlns.com/foaf/0.1/familyName> ‘Camarda’ ;
<http://xmlns.com/foaf/0.1/firstName> ‘Diego’ ;
<http://xmlns.com/foaf/0.1/gender> ‘male’ ;
<http://www.w3.org/1999/...#type> <http://xmlns.com/foaf/0.1/Person> ;
<http://www.w3.org/ns/org#memberOf> <http://www.regesta.com/about> .
<http://www.regesta.com/about>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<http://www.w3.org/ns/org#Organization> .

26. Go Triples, go!
building a graph
<http://www.regesta.com/diego>
<http://xmlns.com/foaf/0.1/familyName> ‘Camarda’ ;
<http://xmlns.com/foaf/0.1/firstName> ‘Diego’ ;
<http://xmlns.com/foaf/0.1/gender> ‘male’ ;
<http://www.w3.org/1999/...#type> <http://xmlns.com/foaf/0.1/Person> ;
<http://www.w3.org/ns/org#memberOf> <http://www.regesta.com/about> .
<http://www.regesta.com/about>
<http://www.w3.org/1999/...#type> <http://www.w3.org/ns/org#Organization> .

27. Go Triples, go!
building a graph
<http://www.regesta.com/diego>
<http://xmlns.com/foaf/0.1/familyName> ‘Camarda’ ;
<http://xmlns.com/foaf/0.1/firstName> ‘Diego’ ;
<http://xmlns.com/foaf/0.1/gender> ‘male’ ;
<http://www.w3.org/1999/...#type> <http://xmlns.com/foaf/0.1/Person> ;
<http://www.w3.org/ns/org#memberOf> <http://www.regesta.com/about> .
<http://www.regesta.com/about>
<http://www.w3.org/1999/...#type> <http://www.w3.org/ns/org#Organization> ;
<http://www.w3.org/2004/02/skos/core#prefLabel> ‘Regesta.exe srl’ ;
<http://xmlns.com/foaf/0.1/homepage> <http://www.regesta.com> .

28. Go Triples, go!
Objects could be Subjects
diego

29. Go Triples, go!
considering diego and regesta
diego
regesta

30. Go Triples, go!
<diego> <memberOf> <regesta>
diego
regesta

31. Go Triples, go!
but, <regesta> <locatedIn> <rome>
diego
regesta
rome

32. Go Triples, go!
<diego> <placeOfBirth> <rome>
diego
regesta
rome

33. Go Triples, go!
<rome> <parentADM> <italy>
diego
regesta
rome
italy

34. Go Triples, go!
<silvia> <placeOfBirth> <italy>
diego
regesta
silvia
rome
italy

35. Go Triples, go!
<silvia> <…> <…>
diego
regesta
silvia
rome
italy

36. Go Triples, go!
<…> <…> <…> = a knowledge graph!
diego
regesta
silvia
rome
italy

37. A lot of sentence
to achieve (descriptive) freedom
<http://www.regesta.com/diego> <http://xmlns.com/foaf/0.1/familyName> ‘Camarda’ .
<http://www.regesta.com/diego> <http://xmlns.com/foaf/0.1/firstName> ‘Diego’ .
<http://www.regesta.com/diego> <http://xmlns.com/foaf/0.1/gender> ‘male’ .
<http://www.regesta.com/diego> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://xmlns.com/foaf/0.1/Person> .
<http://www.regesta.com/diego> <http://www.w3.org/ns/org#memberOf> <http://www.regesta.com> .
<http://www.regesta.com/silvia> <http://xmlns.com/foaf/0.1/familyName> ‘Mazzini’ .
<http://www.regesta.com/silvia> <http://xmlns.com/foaf/0.1/firstName> ‘Silvia’ .
<http://www.regesta.com/silvia> <http://xmlns.com/foaf/0.1/gender> ‘female’ .
<http://www.regesta.com/silvia> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://xmlns.com/foaf/0.1/Person> .
<http://www.regesta.com/silvia> <http://www.w3.org/ns/org#memberOf> <http://www.regesta.com> .
<http://www.regesta.com> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/ns/org#Organization> .
<http://www.regesta.com> <http://www.w3.org/2004/02/skos/core#prefLabel> ‘Regesta.exe srl’ .
<http://www.regesta.com/silvia> <http://xmlns.com/foaf/0.1/knows> <http://www.regesta.com/diego> .
<…> <…> <…>.
<noBeer> <makeGoCreazy> <homer>. <noTv> <makeGoCreazy> <homer>.<noBeer> <makeGoCreazy> <homer>. <noTv>
<makeGoCreazy> <homer>. <noBeer> <makeGoCreazy> <homer>. <noTv> <makeGoCreazy> <homer>. <noBeer>
<makeGoCreazy> <homer>. <noTv> <makeGoCreazy> <homer>. <noBeer> <makeGoCreazy> <homer>. <noTv> <makeGoCreazy>
<homer>. <noBeer> <makeGoCreazy> <homer>. <noTv> <makeGoCreazy> <homer>. <noBeer> <makeGoCreazy> <homer>.
<noTv> <makeGoCreazy> <homer>. <noBeer> <makeGoCreazy> <homer>. <noTv> <makeGoCreazy> <homer>. <noBeer>
<makeGoCreazy> <homer>. <noTv> <makeGoCreazy> <homer>. <noBeer> <makeGoCreazy> <homer>. <noTv> <makeGoCreazy>
<homer>. <noBeer> <makeGoCreazy> <homer>. <noTv> <makeGoCreazy> <homer>. <noBeer> <makeGoCreazy> <homer>.
<noTv> <makeGoCreazy> <homer>. <noBeer> <makeGoCreazy> <homer>. <noTv> <makeGoCreazy> <homer>. <noBeer>
<makeGoCreazy> <homer>. <noTv> <makeGoCreazy> <homer>. <noBeer> <makeGoCreazy> <homer>. <noTv> <makeGoCreazy>
<homer>. <noBeer> <makeGoCreazy> <homer>. <noTv> <makeGoCreazy> <homer>. <noBeer> <makeGoCreazy> <homer>.
<noTv> <makeGoCreazy> <homer>. <noBeer> <makeGoCreazy> <homer>. <noTv> <makeGoCreazy> <homer>. <noBeer> …

38. Standards for
semantic web

39. RDF
http://www.w3.org/standards/techs/rdf
SPARQL
http://www.w3.org/standards/techs/sparql
ONTOLOGIES
http://www.w3.org/standards/semanticweb/ontology
Did you studied HTML? Good!
it's time for a new standard

40. The Resource Description Framework
is a general-purpose language for representing
information in the Web.
It's time for a new standard
RDF

41. The SPARQL Protocol and RDF Query Language
is a query language and protocol for RDF.
It's time for a new standard
SPARQL

42. On the Semantic Web, vocabularies define
the concepts and relationships
(also referred to as “terms”)
used to describe and represent
an area of concern.
It's time for a new standard
Ontologies

43. PREFIX foaf: <http://xmlns.com/foaf/0.1/>
PREFIX dc: <http://purl.org/dc/elements/1.1/>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
foaf:firstName
dc:title
rdfs:label
Pre:fixes (ontologies)
just a few words

44. Browsing the
web of data

45. Resource Description
Framework
› SPARQL endpoint
› dereferenceable URIs
› content negotiation
› standard ports, like 80 (HTTP)
› JSONP support
MUST!

46. Resource Description
Framework
› SPARQL endpoint
› dereferenceable URIs
› content negotiation
› standards port, like 80 (HTTP)
› JSONP support
› up-to-date
› the endpoint URL is easy to deduce from resources
› the resources are described by dc:title or rdfs:label
› the endpoint hosts a page for humans
› the resources and the endpoint are on the same domain
SHOULD!
(please do it, for me)

47. One single API
a world to explore

48. One single API
interlinking
<a href=“…”>click here</a>
owl:sameAs
rdfs:seeAlso
…

49. SELECT * {?minnesota ?banana ?sun}
SPARQL
a must know query language

50. SPARQL
group graph pattern
diego
regesta
silvia
rome
italy
diego
regesta
silvia
rome
italy

51. SPARQL
group graph pattern
diego
regesta
rome
silvia
italy
silvia
italy

52. SELECT ?person {
?person <placeOfBirth> ?place ;
<memberOf> ?company .
?company <locatedIn> ?place .
}
SPARQL
group graph pattern
<diego>

53. SELECT ?person ?prop ?obj {
?person <placeOfBirth> ?place ;
<memberOf> ?company ;
?prop ?obj .
?company <locatedIn> ?place .
}
SPARQL
group graph pattern
(turn the page)

54. person prop obj
<diego> rdf:type foaf:Person
<diego> foaf:firstName ‘Diego’
<diego> foaf:familyName ‘Camarda’
<diego> foaf:gender ‘male’
<diego> org:memberOf <regesta>
SPARQL
group graph pattern

55. DESCRIBE <diego>
SPARQL
describe
(turn the page)

56. <diego> rdf:type foaf:Person .
<diego> foaf:firstName ‘Diego’ .
<diego> foaf:familyName ‘Camarda’ .
<diego> foaf:gender ‘male’ .
<diego> org:memberOf <regesta> .
<silvia> foaf:knows <diego> .
SPARQL
describe

57. CONSTRUCT {<diego> foaf:donaldDuck ?c}
WHERE{<diego> ?b ?c. }
SPARQL
construct
(turn the page)

58. <diego> foaf:donaldDuck foaf:Person .
<diego> foaf:donaldDuck ‘Diego’ .
<diego> foaf:donaldDuck ‘Camarda’ .
<diego> foaf:donaldDuck ‘male’ .
<diego> foaf:donaldDuck <regesta> .
SPARQL
construct

59. DISTINCT, COUNT
GRAPH, PREFIX
isBlank, isIRI, isLiteral, isNumeric
FILTER, REGEX, STR
FILTER NOT EXISTS, MINUS
ORDER BY, OFFSET, LIMIT
for other stuff
http://www.w3.org/TR/sparql11-query/
SPARQL
minimum requirements

60. Please start negotiating content
right now!
Hi dude, I accept:
text/html,application/xhtml+xml
Html
pageGreat! I’ll serve you a web page
Hi dude, I accept:
application/rdf+xml
RDF
dataGreat… 303, redirect!
Hi dude, I accept:
pizza/margherita
406
errormmm… sorry

61. Please start negotiating content
right now!
application/rdf+xml
application/xml
text/plain
text/turtle
application/x-turtle
application/trix
application/x-trig
text/n3
text/rdf+n3
application/trix
application/x-trig
application/x-binary-rdf
text/x-nquads
application/ld+json
application/rdf+json
application/xhtml+xml
text/xml
application/json
application/rdf+xml
application/rdf+n3
application/sparql-results+xml
application/sparql-results+json

62. curl -L -H "Accept: application/rdf+xml"
http://dati.camera.it/ocd/governo.rdf/g102
curl -L -H "Accept: text/n3"
http://dati.camera.it/ocd/governo.rdf/g102
Please start negotiating content
using CURL…

63. Java : Sesame / Jena
Python : RDFLib
Ruby : RDF.rb
nodeJs : sparql-client
or, as I do,
simple HTTP GET +
parsing result as json or xml
Please start negotiating content
…or a framework!

64. RDF data
storing and deploying

65. It’s slow
so keep calm
1 record 15 triples
2.949.771 votes 64.948.856 triples
usually
eg. Chamber of deputies
data big data
RDF probably will transform

66. Virtuoso
Sesame
Fuseki (Jena)
Owlim / Bigdata (Sesame)
AllegroGraph
D2R server
ARC2
…
Triplestores
I just need a SPARQL endpoint
I just really need http://yourdomain/sparql

67. Case studies

68. select distinct ?o where {?s a ?o}
select ?o count(distinct ?s) where {?s a ?o}
select count(?s) where {?s ?p ?o}
select count(?s) ?class where {?s ?p ?o; a ?class}
select distinct ?p where {?s a <http://classe>; ?p ?o}
select ?p count(?p) where {?s a <http://classe>; ?p ?o}
select ?s where {?s a <http://classe>}
?p ?o where {<http://URI> ?p ?o} ?p ?o ?p1 ?o2
where {<http://URI> ?p ?o. OPTIONAL{?o ?p1 ?o2. FILTER(isBlank(?o))}}
select distinct ?s ?title where {?s a <http://classe>;
dc:title ?title. FILTER(REGEX(? title,’parola’,’i’))} LIMIT 100
SPARQL magic
a query for all seasons

69. Case studies
Chamber of deputies

70. http://dati.camera.it/sparql
http://storia.camera.it
From SPARQL
to html

71. Case studies
Central State Archive

72. http://acs.beniculturali.it/sparql
http://labs.regesta.com/reloadProject
From SPARQL
to html

73. Useful links

74. W3C standards
http://www.w3.org/standards/semanticweb/
OKFN endpoints status (and list)
http://sparqles.okfn.org
LodLive (a SPRQL navigator)
http://en.lodlive.it
a very good intro to RDF
https://github.com/JoshData/rdfabout/blob/gh-pages/intro-to-rdf.md
Tim Berners-Lee’s “Linked Data – 5 stars ranking”
http://www.w3.org/DesignIssues/LinkedData.html
My github page
http://github.com/dvcama
My email
mailto:diego.camarda@regesta.com