Resource description framework

1. Resource Description Framework
STANLEY WANG
SOLUTION ARCHITECT, TECH LEAD
@SWANG68
http://www.linkedin.com/in/stanley-wang-a2b143b

2. • RDF is a W3C standard, which
 provides tool to describe Web resources
 provides interoperability between applications that exchange machine-
understandable information
• Composed of three basic elements
 Resources – the things being described
 Properties – the relationships between things
 Classes – the buckets used to group the things
Resource Description Framework
The elements are combined to make simple statements in the form of Triples:
<Subject> <Predicate> <Object>
Men In Black stars Will Smith  <MenInBlack> <hasStar> <WillSmith>

3. Mary
Director
Secretary
to_be_in_
love_with
has_job
has_job
John
has_homepage
has_homepage
Ontology
RDF – Describe Semantic Web Resources

4. • Subject of an RDF statement is a resource
• Predicate of an RDF statement is a property of a resource
• Object of an RDF statement is the value of a property of a resource
RDF Statement
RDF Properties: type, subClassOf, subPropertyOf, range , domain, label,comment
Subject (resource) http://www.w3.org/Home/Lassila
Predicate (property) Creator
Object (literal) “Ora Lassila”
Ora Lassila is the creator of the resource
http://www.w3.org/Home/Lassila.

5. RDF Example
Ora Lassila is the creator of the resource
http://www.w3.org/Home/Lassila.
<rdf:RDF>
<rdf:Description about=
"http://www.w3.org/Home/Lassila">
<s:Creator>Ora Lassila</s:Creator>
</rdf:Description>
</rdf:RDF>
Predicate

6. RDF for Semantic Annotation
• RDF provides metadata about Web resources
• Object -> Attribute-> Value triples
• It has an XML syntax
• Chained triples form a Graph
http://sepang.nottingham.edu.my/~bpayam/images/payam-barnaghi.png
has_image
#Payam payam@nottingh
am
has_emailUNiM
has_teaching
http://www.nottingham.edu.my/CSIT/G53ELC
has_owner
<rdf:Description rdf:about=“#Payam”>
<has_email>payam@nottingham</has_email>
</rdf:Description>
http://sepang.nottingham.edu.my/~bpayam/#Payam

7. RDF Schema
• RDF Schema augments RDF to allow you to define
vocabulary terms and the relations between those terms;
• “extra meaning” to particular RDF predicates and
resources e.g., Class, subClassOf, Property, domain, range
• These terms are the RDF Schema building blocks
(constructors) used to create vocabularies;
• RDF semantically extends RDF by providing a means to
describe RDF Vocabularies;
RDF Schema is a W3C standard which defines vocabulary for RDF
organizes this vocabulary in a typed hierarchy capable to explicitly
declare semantic relations between vocabulary terms

8. What does RDF Schema add?
• Defines vocabulary for RDF
• Organizes this vocabulary in a typed hierarchy
• class, subClassOf, type
• property, subPropertyOf
• domain, range
AlanTom
Staff
Lecturer Research Assistant
subClassOf
subClassOf
type
supervisedBy
domain range
type
supervisedBy
Schema(RDFS)
Data(RDF)

9. Limitation of RDF
• RDF Schema is a vocabulary description language for
describing properties and classes of RDF resources, with a
semantics for generalization hierarchies of such properties
and classes.
• RDFS is useful, but does not solve all possible requirements.
• Complex applications may want more possibilities:
o similarity and/or differences of terms such as properties or classes
o construct classes, not just name them
o can a program reason about some terms? e.g. “if «Person» resources
«A» and «B» have the same «foaf:email» property, then «A» and «B»
are identical”
This lead to the development of OWL (Web Ontology Language)