linked data, rdf & sparql
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http://creativecommons.org/licenses/by/2.0/uk/
Linked Data, RDF & SPARQLRob StylesSenior Technical Consultant
Tim Berners Lee on Linked Data at TED, By PhOtOnQuAnTiQuE, CC-BY-NC-SA on Flickr, http://www.flickr.com/photos/photonquantique/3272712288/
Linked Data
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.
Sir Tim Berners-Lee, http://www.w3.org/DesignIssues/LinkedData
What isLinked Data?
What isThe Web of Documents?
The Web of Documents
A global network of linked documents
A place where anyone can say anything about anything
A vast collection of human-readable knowledge (and opinion)
Documents are linked, but links are not qualified
Linked Data
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.
Sir Tim Berners-Lee, http://www.w3.org/DesignIssues/LinkedData
The Web of Documents
A global network of linked documents
A place where anyone can say anything about anything
A vast collection of human-readable knowledge (and opinion)
Documents are linked, but links are not qualified
The Web of Data
A global network of linked statements
A place where anyone can say anything about anything
A vast collection of machine-readable knowledge (and opinion)
Statements are linked, and links are qualified
What is RDF?
RDF is ...
Resource Description Frameworkhttp://www.w3.org/RDF/
A simple, powerful, data model
Used to define relationships between things
Designed to work with the architecture of the web
The data model for the Web of Data
Allow anyoneto say anythingabout anything
http://nssdc.gsfc.nasa.gov/nmc/spacecraftDisplay.do?
id=1969-059A
NASA - NSSDC - Spacecraft - Detailstitle
23 November 2009published
Apollo 11 Command and Service Moduleabout
Web Pagea Spacecrafta
Apollo 11 Command and Service Modulename
16 July 1969launched
15702size 28801.0mass
Apollo 11 Command and Service Module
Spacecrafta
Apollo 11 Command and Service Modulename
16 July 1969launched
28801.0mass
Cape Canaveral
Cape Canaveral, United States name
launchsite
Resources...
Represent things on the web, like web pages
Represent things not on the web, like people and places
Can represent anything at all
Named using URIs (usually)
Values...
Values can be ‘literal’ values or other resources
Literal values are to work with and show users
Literal values can have specific types (numbers, dates) and language codes (en-gb, cy-gb)
Other resources are URIs to follow and find more data
Properties are...
The relationship between Resources
Named using URIs
Described in Schema(or vocabularies, or ontologies)
Apollo 11 Command and Service Module Cape Canaveral Cape Canaveral,
United States namelaunchsite
Apollo 11 Command and Service Module Cape Canaveral Cape Canaveral,
United States namelaunchsite
Apollo 11 Command and Service Module Cape Canaveral Cape Canaveral,
United States namelaunchsite
Subject Property Value
Apollo 11 Command and Service Module Cape Canaveral Cape Canaveral,
United States namelaunchsite
Subject Property Value
Subject Property Value
Apollo 11 Command and Service Module Cape Canaveral Cape Canaveral,
United States namelaunchsite
Subject Property Value
Subject Property Value
Statement or Triple
Apollo 11 Command and Service Module Cape Canaveral Cape Canaveral,
United States namelaunchsite
Subject Property Value
Subject Property Value
Statement or Triple
Statement or Triple
Simple Rules for Merging
URIs name the resources we are describing
Two people using the same URI are describing the same thing
The same URI in two datasets becomes one URI with all of the properties from both datasets
RDF data can use URIs from many different websites
Apollo 11 Command and Service Module
Spacecrafta
Apollo 11 Command and Service Modulename
16 July 1969launched
28801.0mass
Cape Canaveral
Cape Canaveral, United States name
launchsitehttp://.../1969-059A
http://.../Spacecraft
http://.../cape+cana...
http://.../cape+cana...
N 28° 27' 31''latitude
W 80° 31' 59''longitude
Apollo 11 Command and Service Module
Spacecrafta
Apollo 11 Command and Service Modulename
16 July 1969launched
28801.0mass
Cape Canaveral
Cape Canaveral, United States name
launchsitehttp://.../1969-059A
http://.../Spacecraft
http://.../cape+cana...
http://.../cape+cana...
N 28° 27' 31''latitude
W 80° 31' 59''longitude
Simple Rules for Merging
Graphs from several different sources can be merged
Resources with the same URI are considered identical
No limitations on which graphs can be merged
Any RDF can be merged with any other
RDF
RDF...
is a Graph data modelXML is a tree data modelRDBMS is a table data model
can be easily distributed
can be easily merged
allows anyone say anything about anything
is not newthe spec is from 1999the idea stems back to the late 1960s
What does RDF look like?
Writing RDF
TurtleWhat I’m about to show you
N-TriplesOne statement per line, subset of Turtle, grep compatible
RDF/JSONUseful for AJAX Applications and anything with else JSON support
RDFaWriting RDF within HTML pages
RDF/XMLMachine to Machine TransferDe-facto Standard
Turtle (TTL) stands for Terse Triple Language
Turtle
Terse Triple Language (TTL)http://www.w3.org/2007/02/turtle/primer/
A human-readable notation for RDF
Provides useful syntax for quickly hand-writing RDF
Forms the basis of patterns in SPARQL
http://.../1969-059A
http://.../Spacecraft
a
<http://.../1969-059A> a <http://.../Spacecraft> .
http://.../1969-059A
http://.../Spacecraft
a
Apollo 11 Command and Service Modulename
16 July 1969launched
28801.0mass
<http://example.com/spacecraft/1969-059A>
a space:Spacecraft ;
space:name "Apollo 11 Command and Service Module" ;
space:launched "1969-07-16"^^xsd:date ;
@prefix space: <http://example.com/space-schema/> .@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
space:mass 28801.0 .
http://.../1969-059A
http://.../Spacecraft
a
Apollo 11 Command and Service Modulename
16 July 1969launched
28801.0mass
http://.../cape+cana...
Cape Canaveral, United States name
launchsite
<http://example.com/spacecraft/1969-059A>
a space:Spacecraft ;
space:name "Apollo 11 Command and Service Module" ;
space:launched "1969-07-16"^^xsd:date ;
@prefix space: <http://example.com/space-schema/> .@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
space:mass 28801.0 .
http://.../1969-059A
http://.../Spacecraft
a
Apollo 11 Command and Service Modulename
16 July 1969launched
28801.0mass
http://.../cape+cana...
Cape Canaveral, United States name
launchsite
<http://example.com/spacecraft/1969-059A>
a space:Spacecraft ;
space:name "Apollo 11 Command and Service Module" ;
space:launched "1969-07-16"^^xsd:date ;
@prefix space: <http://example.com/space-schema/> .@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
space:launchsite <http://.../cape+cana...> .
space:mass 28801.0 . space:mass 28801.0 ;
http://.../1969-059A
http://.../Spacecraft
a
Apollo 11 Command and Service Modulename
16 July 1969launched
28801.0mass
http://.../cape+cana...
Cape Canaveral, United States name
launchsite
<http://example.com/spacecraft/1969-059A>
a space:Spacecraft ;
space:name "Apollo 11 Command and Service Module" ;
space:launched "1969-07-16"^^xsd:date ;
@prefix space: <http://example.com/space-schema/> .@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
<http://.../cape+cana...> space:name "Cape Canaveral, United States"@en-us .
space:launchsite <http://.../cape+cana...> .
space:mass 28801.0 . space:mass 28801.0 ;
How do I SPARQL?
SPARQL
Query Language for RDFhttp://www.w3.org/TR/rdf-sparql-query
SPARQL Protocol and RDF Query Language
Graph pattern based languagewritten the same as Turtle
Several queries — Ask; Select; Describe; Construct
Read Onlystill vulnerable to injection, though not as bad as SQL
Space Physicsspace:Discipline
space:Spacecraft
space:Launch
space:Launchsite
/discipline/spacephysics
/spacecraft/1957-001B
/launch/1957-001
/launchsite/tyurata
a
a
a
a
space:discipline
space:spacecraft
space:launchsite
Sputnik 1
The Sputnik 1 spacecraft was ...
U.S.S.R
86.3
1957-10-04
Modified SS-6 (Sapwood)
Tyuratam (Baikonur Cosmodrome)
U.S.S.R
rdfs:label
space:country
foaf:name
dc:description
space:agency
space:mass
space:launched
space:launchvehicle
rdfs:label
/images/sputnik.jpgfoaf:depiction
Triple Patterns
Triple Patterns
<http://example.com/spacecraft/1957-001B> foaf:name "Sputnik 1" .
Triple Patterns
<http://example.com/spacecraft/1957-001B> foaf:name "Sputnik 1" .
?something foaf:name "Sputnik 1" .
Triple Patterns
<http://example.com/spacecraft/1957-001B> foaf:name "Sputnik 1" .
?something foaf:name "Sputnik 1" .
?something foaf:name ?name .
Triple Patterns
<http://example.com/spacecraft/1957-001B> foaf:name "Sputnik 1" .
?something foaf:name "Sputnik 1" .
?something foaf:name ?name .
SELECT ?name WHERE { ?something foaf:name ?name .}
Space Physicsspace:Discipline
space:Spacecraft
space:Launch
space:Launchsite
/discipline/spacephysics
/spacecraft/1957-001B
/launch/1957-001
/launchsite/tyurata
a
a
a
a
space:discipline
space:spacecraft
space:launchsite
Sputnik 1
The Sputnik 1 spacecraft was ...
U.S.S.R
86.3
1957-10-04
Modified SS-6 (Sapwood)
Tyuratam (Baikonur Cosmodrome)
U.S.S.R
rdfs:label
space:country
foaf:name
dc:description
space:agency
space:mass
space:launched
space:launchvehicle
rdfs:label
/images/sputnik.jpgfoaf:depiction
Triple Patterns
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
SELECT ?label WHERE { ?something rdfs:label ?label .}
Space Physicsspace:Discipline
space:Spacecraft
space:Launch
space:Launchsite
/discipline/spacephysics
/spacecraft/1957-001B
/launch/1957-001
/launchsite/tyurata
a
a
a
a
space:discipline
space:spacecraft
space:launchsite
Sputnik 1
The Sputnik 1 spacecraft was ...
U.S.S.R
86.3
1957-10-04
Modified SS-6 (Sapwood)
Tyuratam (Baikonur Cosmodrome)
U.S.S.R
rdfs:label
space:country
foaf:name
dc:description
space:agency
space:mass
space:launched
space:launchvehicle
rdfs:label
/images/sputnik.jpgfoaf:depiction
Space Physicsspace:Discipline
space:Spacecraft
space:Launch
space:Launchsite
/discipline/spacephysics
/spacecraft/1957-001B
/launch/1957-001
/launchsite/tyurata
a
a
a
a
space:discipline
space:spacecraft
space:launchsite
Sputnik 1
The Sputnik 1 spacecraft was ...
U.S.S.R
86.3
1957-10-04
Modified SS-6 (Sapwood)
Tyuratam (Baikonur Cosmodrome)
U.S.S.R
rdfs:label
space:country
foaf:name
dc:description
space:agency
space:mass
space:launched
space:launchvehicle
rdfs:label
/images/sputnik.jpgfoaf:depiction
Triple Patterns
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
SELECT ?label WHERE { ?something rdfs:label ?label ; rdf:type space:Discipline .}
Space Physicsspace:Discipline
space:Spacecraft
space:Launch
space:Launchsite
/discipline/spacephysics
/spacecraft/1957-001B
/launch/1957-001
/launchsite/tyurata
a
a
a
a
space:discipline
space:spacecraft
space:launchsite
Sputnik 1
The Sputnik 1 spacecraft was ...
U.S.S.R
86.3
1957-10-04
Modified SS-6 (Sapwood)
Tyuratam (Baikonur Cosmodrome)
U.S.S.R
rdfs:label
space:country
foaf:name
dc:description
space:agency
space:mass
space:launched
space:launchvehicle
rdfs:label
/images/sputnik.jpgfoaf:depiction
Space Physicsspace:Discipline
space:Spacecraft
space:Launch
space:Launchsite
/discipline/spacephysics
/spacecraft/1957-001B
/launch/1957-001
/launchsite/tyurata
a
a
a
a
space:discipline
space:spacecraft
space:launchsite
Sputnik 1
The Sputnik 1 spacecraft was ...
U.S.S.R
86.3
1957-10-04
Modified SS-6 (Sapwood)
Tyuratam (Baikonur Cosmodrome)
U.S.S.R
rdfs:label
space:country
foaf:name
dc:description
space:agency
space:mass
space:launched
space:launchvehicle
rdfs:label
/images/sputnik.jpgfoaf:depiction
Triple Patterns
PREFIX space: <http://purl.org/net/schemas/space/>
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
SELECT ?launchdate WHERE { ?spacecraft foaf:name “Sputnik 1” . ?launch space:spacecraft ?spacecraft . ?launch space:launched ?launchdate .}
Space Physicsspace:Discipline
space:Spacecraft
space:Launch
space:Launchsite
/discipline/spacephysics
/spacecraft/1957-001B
/launch/1957-001
/launchsite/tyurata
a
a
a
a
space:discipline
space:spacecraft
space:launchsite
Sputnik 1
The Sputnik 1 spacecraft was ...
U.S.S.R
86.3
1957-10-04
Modified SS-6 (Sapwood)
Tyuratam (Baikonur Cosmodrome)
U.S.S.R
rdfs:label
space:country
foaf:name
dc:description
space:agency
space:mass
space:launched
space:launchvehicle
rdfs:label
/images/sputnik.jpgfoaf:depiction
Space Physicsspace:Discipline
space:Spacecraft
space:Launch
space:Launchsite
/discipline/spacephysics
/spacecraft/1957-001B
/launch/1957-001
/launchsite/tyurata
a
a
a
a
space:discipline
space:spacecraft
space:launchsite
Sputnik 1
The Sputnik 1 spacecraft was ...
U.S.S.R
86.3
1957-10-04
Modified SS-6 (Sapwood)
Tyuratam (Baikonur Cosmodrome)
U.S.S.R
rdfs:label
space:country
foaf:name
dc:description
space:agency
space:mass
space:launched
space:launchvehicle
rdfs:label
/images/sputnik.jpgfoaf:depiction
Space Physicsspace:Discipline
space:Spacecraft
space:Launch
space:Launchsite
/discipline/spacephysics
/spacecraft/1957-001B
/launch/1957-001
/launchsite/tyurata
a
a
a
a
space:discipline
space:spacecraft
space:launchsite
Sputnik 1
The Sputnik 1 spacecraft was ...
U.S.S.R
86.3
1957-10-04
Modified SS-6 (Sapwood)
Tyuratam (Baikonur Cosmodrome)
U.S.S.R
rdfs:label
space:country
foaf:name
dc:description
space:agency
space:mass
space:launched
space:launchvehicle
rdfs:label
/images/sputnik.jpgfoaf:depiction
Space Physicsspace:Discipline
space:Spacecraft
space:Launch
space:Launchsite
/discipline/spacephysics
/spacecraft/1957-001B
/launch/1957-001
/launchsite/tyurata
a
a
a
a
space:discipline
space:spacecraft
space:launchsite
Sputnik 1
The Sputnik 1 spacecraft was ...
U.S.S.R
86.3
1957-10-04
Modified SS-6 (Sapwood)
Tyuratam (Baikonur Cosmodrome)
U.S.S.R
rdfs:label
space:country
foaf:name
dc:description
space:agency
space:mass
space:launched
space:launchvehicle
rdfs:label
/images/sputnik.jpgfoaf:depiction
Example Select
PREFIX space: <http://purl.org/net/schemas/space/>PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
SELECT ?subject ?label WHERE {
?subject rdfs:label ?label ; a space:Discipline .
}
Example Select<sparql xmlns="http://www.w3.org/2005/sparql-results#"> <head> <variable name="subject"/> <variable name="label"/> </head> <results> <result> <binding name="subject"> <uri>http://nasa.dataincubator.org/discipline/astronomy</uri> </binding> <binding name="label"> <literal>Astronomy</literal> </binding> </result> <result> <binding name="subject"> <uri>http://nasa.dataincubator.org/discipline/communications</uri> </binding> <binding name="label"> <literal>Communications</literal>
Example Select
PREFIX space: <http://purl.org/net/schemas/space/>PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
SELECT * WHERE {
?subject rdfs:label ?label ; a space:Discipline .
}
Space Physicsspace:Discipline
space:Spacecraft
space:Launch
space:Launchsite
/discipline/spacephysics
/spacecraft/1957-001B
/launch/1957-001
/launchsite/tyurata
a
a
a
a
space:discipline
space:spacecraft
space:launchsite
Sputnik 1
The Sputnik 1 spacecraft was ...
U.S.S.R
86.3
1957-10-04
Modified SS-6 (Sapwood)
Tyuratam (Baikonur Cosmodrome)
U.S.S.R
rdfs:label
space:country
foaf:name
dc:description
space:agency
space:mass
space:launched
space:launchvehicle
rdfs:label
/images/sputnik.jpgfoaf:depiction
Example QueryPREFIX space: <http://purl.org/net/schemas/space/>PREFIX foaf: <http://xmlns.com/foaf/0.1/>PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
SELECT ?name ?mass WHERE{ ?launch space:launched ?date ; space:spacecraft ?spacecraft .
?spacecraft foaf:name ?name ; space:mass ?mass .
FILTER ( ?date >= "1965-01-01"^^xsd:date && ?date <= "1975-12-31"^^xsd:date )}ORDER BY DESC(?mass)LIMIT 10OFFSET 10
Tip 1: Find all the Properties
SELECT DISTINCT ?p WHERE {
?s ?p ?o .
}
Space Physicsspace:Discipline
space:Spacecraft
space:Launch
space:Launchsite
/discipline/spacephysics
/spacecraft/1957-001B
/launch/1957-001
/launchsite/tyurata
a
a
a
a
space:discipline
space:spacecraft
space:launchsite
Sputnik 1
The Sputnik 1 spacecraft was ...
U.S.S.R
86.3
1957-10-04
Modified SS-6 (Sapwood)
Tyuratam (Baikonur Cosmodrome)
U.S.S.R
rdfs:label
space:country
foaf:name
dc:description
space:agency
space:mass
space:launched
space:launchvehicle
rdfs:label
/images/sputnik.jpgfoaf:depiction
Space Physicsspace:Discipline
space:Spacecraft
space:Launch
space:Launchsite
/discipline/spacephysics
/spacecraft/1957-001B
/launch/1957-001
/launchsite/tyurata
a
a
a
a
space:discipline
space:spacecraft
space:launchsite
Sputnik 1
The Sputnik 1 spacecraft was ...
U.S.S.R
86.3
1957-10-04
Modified SS-6 (Sapwood)
Tyuratam (Baikonur Cosmodrome)
U.S.S.R
rdfs:label
space:country
foaf:name
dc:description
space:agency
space:mass
space:launched
space:launchvehicle
rdfs:label
/images/sputnik.jpgfoaf:depiction
Tip 2: Find all the Classes
SELECT DISTINCT ?type WHERE {
?s a ?type .
}
Space Physicsspace:Discipline
space:Spacecraft
space:Launch
space:Launchsite
/discipline/spacephysics
/spacecraft/1957-001B
/launch/1957-001
/launchsite/tyurata
a
a
a
a
space:discipline
space:spacecraft
space:launchsite
Sputnik 1
The Sputnik 1 spacecraft was ...
U.S.S.R
86.3
1957-10-04
Modified SS-6 (Sapwood)
Tyuratam (Baikonur Cosmodrome)
U.S.S.R
rdfs:label
space:country
foaf:name
dc:description
space:agency
space:mass
space:launched
space:launchvehicle
rdfs:label
/images/sputnik.jpgfoaf:depiction
Space Physicsspace:Discipline
space:Spacecraft
space:Launch
space:Launchsite
/discipline/spacephysics
/spacecraft/1957-001B
/launch/1957-001
/launchsite/tyurata
a
a
a
a
space:discipline
space:spacecraft
space:launchsite
Sputnik 1
The Sputnik 1 spacecraft was ...
U.S.S.R
86.3
1957-10-04
Modified SS-6 (Sapwood)
Tyuratam (Baikonur Cosmodrome)
U.S.S.R
rdfs:label
space:country
foaf:name
dc:description
space:agency
space:mass
space:launched
space:launchvehicle
rdfs:label
/images/sputnik.jpgfoaf:depiction
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