wtf is semantic web?
TRANSCRIPT
Normal Web is about making information accessible to people.
Semantic Web is about making information more accessible
to software.
Thank you Wikipedians
(Thank you, Wikipedians)
oh well, it'll
http://en.wikipedia.org/wiki/Michael_Jackson_(footballer)
• Give important things identifiers
How?
407161495 ?
footballer_f285n ?
michael_jackson_27 ?
http://en.wikipedia.org/wiki/Michael_Jackson_(footballer)
URIs and URLs
• They look exactly like URLs
• In fact, URLs are a type of URI
URI: An identifier
URL: An identifier that points to a document
• They look exactly like URLs
• In fact, URLs are a type of URI
http://en.wikipedia.org/wiki/Michael_Jackson_(footballer)
URL
URI
URIs and URLs
• They look exactly like URLs
• In fact, URLs are a type of URI
http://milesworthington.com/Michael_Jackson(page does not exist)
URL
URI
URIs and URLs
URIs and URLs
• They look exactly like URLs
• In fact, URLs are a type of URI
Often the same.
But URIs do not always point to actual pages. Sometimes they are just names.
• Give important things identifiers
• Also give identifiers to the relationships between things
How?
http://jimsblog.com/michael_jackson_match.html
http://en.wikipedia.org/wiki/Michael_Jackson_(footballer)
Traditional Web links
http://jimsblog.com/michael_jackson_match.html
foaf:primaryTopic
http://en.wikipedia.org/wiki/Michael_Jackson_(footballer)
Semantic Web links
http://jimsblog.com/michael_jackson_match.html
foaf:primaryTopic
http://en.wikipedia.org/wiki/Michael_Jackson_(footballer)
(URI in disguise)
http://jimsblog.com/michael_jackson_match.html
http://xmlns.com/foaf/0.1/primaryTopic
http://en.wikipedia.org/wiki/Michael_Jackson_(footballer)
Jim’s blog post
has a the primary topic of
Michael Jackson the football player
Jim’s blog post
has a the primary topic of
Michael Jackson the football player
This is referred to as a “triple”
DBpedia.org
• The Semantic Web version of Wikipedia
• Contains all the same content from Wikipedia
• Everything is given a URI
• Relationships between things are also expressed with a URI
• Uses Tim’s Linked Data principles
MJ’s DBpedia URI
http://dbpedia.org/resource/Michael_Jackson
http://dbpedia.org/resource/Michael_Jackson http://dbpedia.org/page/Michael_Jackson
http://dbpedia.org/resource/Michael_Jackson http://dbpedia.org/data/Michael_Jackson.xml
Michael Jackson
was born in
Gary, Indiana
“Triples”
“Triples”
http://dbpedia.org/resource/Michael_Jackson
http://dbpedia.org/ontology/birthPlace
http://dbpedia.org/resource/Gary%2C_Indiana
“Triples”
SUBJECT
PREDICATE
OBJECT
“Triples”
http://dbpedia.org/resource/Michael_Jackson
http://dbpedia.org/ontology/birthDate
“1958-08-29”
http://www.imdb.com/name/nm0001391/
http://www.w3.org/2002/07/owl#sameAs
http://dbpedia.org/resource/Michael_Jackson
RDF
• “Resource Description Framework”
• Provides a way to add identifiers (URIs)to content
• Comes in many flavors
RDF
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .@prefix dc: <http://purl.org/dc/elements/1.1/> .@prefix ex: <http://example.org/stuff/1.0/> .
<http://www.w3.org/TR/rdf-syntax-grammar> dc:title "RDF/XML Syntax Specification (Revised)" ; ex:editor [ ex:fullname "Dave Beckett"; ex:homePage <http://purl.org/net/dajobe/> ] .
Turtle format
RDF
<http://www.w3.org/2001/sw/RDFCore/ntriples/> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> ↵ <http://xmlns.com/foaf/0.1/Document> .<http://www.w3.org/2001/sw/RDFCore/ntriples/> <http://purl.org/dc/terms/title> "N-Triples"@en-US .<http://www.w3.org/2001/sw/RDFCore/ntriples/> <http://xmlns.com/foaf/0.1/maker> _:art .<http://www.w3.org/2001/sw/RDFCore/ntriples/> <http://xmlns.com/foaf/0.1/maker> _:dave .
_:art <http://www.w3.org/1999/02/22-rdf-syntax-ns#> <http://xmlns.com/foaf/0.1/Person> ._:art <http://xmlns.com/foaf/0.1/name> "Art Barstow".
_:dave <http://www.w3.org/1999/02/22-rdf-syntax-ns#> <http://xmlns.com/foaf/0.1/Person> ._:dave <http://xmlns.com/foaf/0.1/name> "Dave Beckett".
N-triples format
RDF
<rdf:RDF xmlns="http://xmlns.com/foaf/0.1/" xmlns:dc="http://purl.org/dc/terms/" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"> <Document rdf:about="http://www.w3.org/2001/sw/RDFCore/ntriples/"> <dc:title xml:lang="en-US">N-Triples</dc:title> <maker> <Person rdf:nodeID="art"> <name>Art Barstow</name> </Person> </maker> <maker> <Person rdf:nodeID="dave"> <name>Dave Beckett</name> </Person> </maker> </Document></rdf:RDF>
RDF/XML
The Compromise: RDFa
• RDF that lives inside an HTML document
• The “a” stands for attributes
• Uses attributes on HTML tags to hold identifiers
The Compromise: RDFa
<p xmlns:dc="http://purl.org/dc/elements/1.1/" about="http://www.example.com/books/wikinomics"> In his latest book <cite property="dc:title">Wikinomics</cite>, <span property="dc:creator">Don Tapscott</span> explains deep changes in technology, demographics and business. The book is due to be published in <span property="dc:date" content="2006-10-01">October 2006</span>.</p>
RDFa
Geek Reason
When most of the Web is published with RDF/RDFa it becomes a giant database
that we can efficiently query.
... a unified API for the Web
Geek Reason
“Find all <type:blog_post> that are <type:book_review> for <My_Favorite_Book> published between <date:one_month_ago> and <date:now>”
Lots of new terms
• Linked Data: connecting data through identifiers
• triples: <MJ> <born in> <Indiana>
• RDF: A way to describe content using identifiers
• SPARQL: A query language for triples
• ontology: A big vocabulary that defines URIs for classifying things and relationships