this lecture is about information technology.

1. UNIVERSITY OF AJDABIYA
Faculty of informationTechnology
informationTechnology Department Program
COURSE NAME SemanticWeb
COURSECODE IT302

2. INTRODUCTIONTOTHE
SEMANTICWEB
Introduction to the SemanticWeb 1

3. Agenda
What is the Semantic Web?
What is data in the SemanticWeb?
Storing and publishing semantic data
Querying the Semantic Web
What is there for developers?
How does the Semantic Web compare?
So who actually does the SemanticWeb?

4. What is the Semantic
Web?

5. What is the Semantic Web?
This course is about something we call the
Semantic Web. From the name, you can
probably guess that it is related somehow
to the World Wide Web (WWW) and that it
has something to do with semantics.
Semantics, in turn, has to do with
understanding the nature of meaning, but
even the word semantics has a number of
meanings. In what sense are we using the
word semantics? And how can it be applied

6. What is the Semantic Web?
perhaps more accurately, the World
Wide Web Consortium (W3C) has
provided these tools in the forms of
standard Semantic Web languages,
complete with abstract syntax,
model-based semantics, reference
implementations, test cases, and
so forth.

7. What is the Semantic Web?
Semantics = meaning (from Greek)
Set of practices and standards
Synonymous or related to:
Web of data
Linked data (cloud)
Giant Global Graph (GGG)
Web 3.0
Open Data
Big Data

8. So what is it about?
Allowing machines to understand
data
Ease sharing and mixing data
Extend the World Wide Web rather
than replace it

9. What Is a Web? The Web
architecture was built by standing on the
shoulders of giants. Writing in The Atlantic
magazine in 1945 [Bush and Wang 1945],
Vannevar Bush identified the problems in
managing large collections of documents
and the links we make between them.

10. What is web?
The Web architecture includes two important
parts: Web clients, the most well known being
the Web browser, and Web servers, which serve
documents and data to the clients whenever
they require it. For this architecture towork,
there have to be three initial essential
components. First, addresses that allow us to
identify and locate the document on theWeb;

11. What is web?
second, communication protocols that allow a
client to connect to a server, send a request, and get
an answer; and third, representation languages to
describe the content of the pages, the documents
that are to be transferred. These three components
comprise a basic Web architecture as described in
Jacobs and Walsh [2004], which the Semantic Web
standards.

12. Little bit of history
1969: paper Semantic Information Processing by
Ross Quillial
1980s: CYC and WordNet
mid- to late 1990s: Tim Berners-Lee coins the term
Semantic Web
Today: dbpedia: 1.2m triples

13. We go beyond only providing a coverage of the
fundamental tools to also show how they can be
used together to create semantic models,
sometimes called ontologies or vocabularies,
that are understandable, useful, durable, and
perhaps even beautiful.

14. SemanticWeb building blocks

15. URI/IRI
Uniform Resource
Identifier

16. It’s all about
resources

17.  Extensive use of URIs (and most
often URLs)
 (Almost) everyting is a URI
 Example URIs:
 http://infusion.com/people/tplu
skiewicz
 urn:isbn:1898432023
http://xmlns.com/foaf/0.1/firs
tName
It’s all about
resources

18. It’s all findable about resources
• Identifier
• Representation
• Resource itself
• URI (URL?)
•HTML, RDF
•Described object
Identifier URI should be different than the
representation URI
Identifiers should not change

19. Cool URIs
Resource and representation have different URIs
Hash URIs
 http://www.example.com/about#alice
 http://www.example.com/about.html
„Normal” URIs
http://www.example.com/id/bob
http://www.example.com/people/bob.html

20. Representing the data

21. Resource Description Format
 Facts and relations organized in triples
 Triples mimic natural language sentences
 Graphical representation is a directed
graph
My name is Tomasz Pluskiewicz.
My age is 26.
I work for Infusion.

22. Resource Description Format

23. Serializing RDF triples
Format
RDF/XML (.rdf)
Notation3 (.n3)
N-Triples (.nt)
Turtle (.ttl)
JSON-LD
TriG (.trig)
TriX (.trix)
MIME type
application/rdf+xml
text/n3
text/plain
text/turtle

24. RDF/XML vsTurtle
RDF/XML
Difficult to author
 Verbose
No cannonical
serialization
Turtle
Simple
 Concise
Has means of further
compressing content

25. There can be multiple graphs
Sets of triples form graphs
Graphs can be named with a URI
Named graph are also resources, hence there can
be triples describing those graphs

26. The basics of semantic data
Adding meaning

27. Representing the data

28. Basics of RDF(S) resources
classes
rdfs:Resource
rdfs:Class
rdfs:Property
rdfs:Datatype
rdfs:Literal
properties
rdf:type
rdfs:label
rdfs:subClassOf
rdfs:subPropertyOf
rdfs:range
rdfs:domain

29. Web Ontology Language
OWL: Lite, DL and Full
OWL 2: EL, QL and RL
Defining constraints
Enables defining complex rules
Uses specialized syntaxes
Base terms:
owl:Thing, owl:Nothing,
owl:DatatypeProperty,
owl:ObjectProperty, owl:sameAs