linked data and rdf
TRANSCRIPT
Linked Data
WWW > Web of Documents
CSV, XML, HTML tables >>> Web of Data
Typed Links, to & from >>> global data graph
LOD
Principles
1. Use URIs to denote things.2. Use HTTP URIs [#, /] so that these things can be
referred to and looked up ("dereferenced") by people and user agents.
3. Provide useful information [metadata (aliases, DC terms, technical: means of access, formats)] about the thing when its URI is dereferenced, leveraging standards such as RDF, SPARQL.
4. Include links to other [!] related things (using their URIs) when publishing data on the Web [reusing vocabularies].
http://en.wikipedia.org/wiki/Linked_data
HUGE2.46 billion pieces of information (RDF triples)
http://lod-cloud.net/ http://dbpedia.org/
http://lov.okfn.org/dataset/lov/index.html
http:
//lo
v.ok
fn.o
rg/d
atas
et/l
ov/d
etai
ls/v
ocab
ular
y_ge
o.ht
ml
RDF (.rdf)
“HTML for data”
<Subject> <Predicate> <Object>
Goals/Applicationstransfer information between machines (not people) without loss of meaning, “identified on the web”
Vocabularies (terms) for statements
Serializations
http:
//w
ww
.w3.
org/
TR/r
df-p
rimer
/
the thing the
property
the value
http:
//w
ww
.w3.
org/
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df-p
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/
http://www.example.org/index.html has a creator whose value is John Smith
http:
//w
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.w3.
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http://www.example.org/index.html has a creator whose value is John Smith
http://www.example.org/index.html has a creation-date whose value is August 16, 1999http://www.example.org/index.html has a language whose value is English
URI refs
plain literals
http:
//w
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.w3.
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df-p
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<http://www.example.org/index.html> <http://purl.org/dc/elements/1.1/creator> <http://www.example.org/staffid/85740> . <http://www.example.org/index.html> <http://www.example.org/terms/creation-date> "August 16, 1999" . <http://www.example.org/index.html> <http://purl.org/dc/elements/1.1/language> "en" .
full triples
prefix ex: namespace URI: http://www.example.org/prefix dc: namespace URI: http://purl.org/dc/elements/1.1/prefix exterms: namespace URI: http://www.example.org/terms/prefix exstaff: namespace URI: http://www.example.org/staffid/
ex:index.html dc:creator exstaff:85740 . ex:index.html exterms:creation-date "August 16, 1999" . ex:index.html dc:language "en" .
QName =
prefix:local
name
(shared) Vocabulariesconve
ntion
fy:joefy.iunm ed:dsfbups fytubgg:85740 . Meaning!
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exstaff:85740 exterms:age "27"^^xsd:integer .
John Smith has a an age whose value is 27
<http://www.example.org/staffid/85740> <http://www.example.org/terms/age> "27"^^<http://www.w3.org/2001/XMLSchema#integer> .
ex:index.html exterms:creation-date "1999-08-16"^^xsd:date .
Concepts Things you should have heard about …
Data types
Blank nodes
Expression of simple facts
Entailment
[Literals, URIrefs, RDF/XML, graphs]
http:
//w
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.w3.
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TR/r
df-c
once
pts
http:
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RDF/XML
http:
//w
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.w3.
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Turtle (.ttl)
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>.@prefix contact: <http://www.w3.org/2000/10/swap/pim/contact#>.
<http://www.w3.org/People/EM/contact#me>rdf:type contact:Person;contact:fullName "Eric Miller";contact:mailbox <mailto:[email protected]>;contact:personalTitle "Dr.".
http://www.w3.org/2007/02/turtle/primer/
Geo and RDF
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:geo="http://www.w3.org/2003/01/geo/wgs84_pos#">
<geo:Point>
<geo:lat>55.701</geo:lat>
<geo:long>12.552</geo:long>
</geo:Point>
</rdf:RDF>
http:
//w
ww
.w3.
org/
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/01/
geo/
#exa
mpl
e
Geo, FOAF & DC<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#" xmlns:geo="http://www.w3.org/2003/01/geo/wgs84_pos#" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns="http://xmlns.com/foaf/0.1/">
<Person>
<name>Dan Brickley</name>
<homepage dc:title="Dan's home page" rdf:resource="http://danbri.org/"/>
<based_near geo:lat="51.47026" geo:long="-2.59466"/>
<rdfs:seeAlso rdf:resource="http:/danbri.org/foaf.rdf"/>
<!-- more RDF here, using any RDF vocabularies -->
</Person>
</rdf:RDF>
http:
//w
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.w3.
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/01/
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#exa
mpl
e
THANKS!Resources and references > see handout!
Linked data applications
browsers – navigate/traverse data sources using links/RDF triples (connecting web of {documents, data})
search engines – start of the navigationhuman-oriented (like Google…)application-oriented (reuse indexing for different apps)
domain applicationsDbpedia Mobile, Revyu, DERI pipes, …
RDFa 1.0 Examplehttp://en.wikipedia.org/wiki/RDFa
RDFs and OWLRDF Schema > http://en.wikipedia.org/wiki/RDF_Schema
Web Ontology Language > http://en.wikipedia.org/wiki/Web_Ontology_Languagemore expressive
See also https://www.cambridgesemantics.com/de/semantic-university/rdfs-vs.-owl