The document discusses Resource Description Framework (RDF), a W3C standard for describing web resources. RDF uses a graph-based data model consisting of subjects, predicates, and objects, known as triples. It provides a common framework for describing resources, along with their properties and relationships. RDF Schema builds upon RDF by defining additional vocabulary terms like class, subClassOf, and domain to organize RDF vocabularies and semantically relate terms. While useful, RDF Schema has limitations, leading to the development of OWL as a more expressive ontology language.

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)