5 mins on RDF

Name: Mischa Tuffield

WebID: http://mmt.me.uk/foaf.rdf#mischa

mailto: [email protected]

Work: Garlik

The Semantic Web Layercake

The new Semantic Web Layercake!?

Semantic Web / The Web of Data 1/2

The Resource Description Framework (RDF) -triples. MIME-types:
- n3 text/rdf+n3
- ntriples text/plain
- turtle application/x-turtle
- RDF-XML application/rdf+xml
Shared Conceptualisations/domain models/ontologies
- A Cat is_a Mammal, Mammals give birth, ...
- Person is an Agent, Agents interact with their environment, A Person can have friends, A person has an age of type integer, with a cardinality of > 0

Semantic Web / The Web of Data 2/2

Uniform Resource Identifiers (URI)

Who knows what a URI is?

A URI is a compact sequence of characters that identifies an abstract concept or a physical resource - RFC3986
foo://bar.com:8001/boo/x?something=value#fragment
\___/\___________/\____/ \_____________/ \______/
scheme authority path query fragment
URIs are NOT merely URLs!
And I should stress that cool ones don't change
- http://
- mailto:
- tag:
- file://
- isbn:
- urn://
- ...

RDF isn't that bad ...

RDF is not simply a flavour of XML, but it can be serialised in XML, but it is very ugly

<?xml version="1.0" encoding="utf-8"?>
<rdf:RDF
	xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
	xmlns:foaf="http://xmlns.com/foaf/0.1/">
 <foaf:PersonalProfileDocument rdf:about="">
	<foaf:primaryTopic rdf:resource="http://mmt.me.uk/foaf.rdf#mischa"/>
 </foaf:PersonalProfileDocument>

 <foaf:Person rdf:ID="mischa">
	<foaf:homepage rdf:resource="http://mmt.me.uk/"/>
 </foaf:Person>
</rdf:RDF>

It can be serialised in other ways to make it easier to read ...

 @prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
 @prefix foaf: <http://xmlns.com/foaf/0.1/> .
  <> a foaf:PersonalProfileDocument ;
  	 foaf:primaryTopic <#mischa> .
  <#mischa> a foaf:Person ;
	foaf:homepage <http://mmt.me.uk/> .

It can even more verbose:

    <http://mmt.me.uk/foaf.rdf> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://xmlns.com/foaf/0.1/PersonalProfileDocument> .
    <http://mmt.me.uk/foaf.rdf> <http://xmlns.com/foaf/0.1/primaryTopic> <http://mmt.me.uk/foaf.rdf#mischa> .
    <http://mmt.me.uk/foaf.rdf#mischa> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://xmlns.com/foaf/0.1/Person> .
    <http://mmt.me.uk/foaf.rdf#mischa> <http://xmlns.com/foaf/0.1/homepage> <http://mmt.me.uk/> .

So what does all of this mean?

Represent your data in triples, use unique identifiers, and make use of as many shared conceptualisations as you can
So what are triples?: Subject Predicate Object
Implied semantics in column name in a class db
And this is very similar in form to the simplest of English sentences
some guy called X has a homepage Y

 <#personX> foaf:homepage <http://foo.com/bar> .

Need to be able to bung any Class/property URI into a web browser to get its description

Content Negotiation

Show /Music example on the BBC

curl -I http://www.bbc.co.uk/music/artists/cc197bad-dc9c-440d-a5b5-d52ba2e14234

Return "text/html"

curl -I -H "Accept: application/rdf+xml" http://www.bbc.co.uk/music/artists/cc197bad-dc9c-440d-a5b5-d52ba2e14234

Return "application/rdf+xml"

http://blog.dbtune.org/post/2009/03/24/A-sneak-peek-at-the-BBC-Music-RDF via Yves Raimond
I generate my homepage from my FOAF file, I just edit it in our foaf builder thing and I write back via webdav, and to OAuth (for private data)

Knowledge Representation and shared conceptualisations

AI winter
CYC project
Wikipedia ... DBpedia the consensus vote ...
Could this be leading us to a Universal Vocabulary?

The Picture 2 Years ago ...

The Picture as of last year ...

The Picture Now

So how does Personal Information fit into all this

Associative Querying
My favourite TimBL picture :

Get involved

Tracks at WWW conferences (Linked Data on the Web 2009) is a good place to start
International Semantic Web Conferences
ESW wiki at the W3C
#swig on irc.freenode.com
This talk can be found at this URL http://mmt.me.uk/slides/london011209
Questions ?