Transcript What is the Semantic Web?

Princess Nora University
Net535
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What is the Semantic Web?
Background
Components of the Semantic Web
Why the Semantic Web is needed
Uses of the Semantic Web
Implementing the Semantic Web
Examples
Conclusion
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As we know today web is linked many
documents made with computer but is
intended to humans understanding only !!!
Even though the web documents are made with
computers, computers can NOT understand the
content of these documents. They can't read,
see relationships or make decisions like human
can. !!!
Most of the Search Engines are based on
keywords which return not accurate and
precise results !!!
The Semantic Web is "an extended web of
machine-readable information and
automated services that amplify the Web
far beyond current capabilities" (Daconta et
al., 2003)
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A framework that:
◦ Adds meaning to data
◦ Provides a mechanism for organizing, interpreting,
and making use of that meaning
Semantic means the study of the meaning
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“The Semantic Web is a major research initiative of the World
Wide Web Consortium (W3C) to create a metadata-rich Web of
resources that can describe themselves not only by how they
should be displayed (HTML) or syntactically (XML), but also by
the meaning of the metadata.”
W3C Semantic Web Page
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An enhancement to the current Web, not a replacement
“The Semantic Web is an extension of the current web in
which information is given well-defined meaning, better
enabling computers and people to work in cooperation.”
et al
The Semantic Web, Scientific American, May 2001 by Tim Berners-Lee
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The term “Semantic Web” refers to W3C’s
vision of the Web of linked data. Semantic
Web technologies enable people to create
data stores on the Web, build vocabularies,
and write rules for handling data. Linked data
are empowered by technologies such as RDF,
SPARQL, OWL, and SKOS.
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It is a vision for the future Web (a web of meaning —
semantics); originally defined by Tim Berners-Lee (aka
father of the Web).
It is not a separate web, but an extension of the current
one.
It provides a way for machines to get much better at being
able to process and understand the data that they merely
display at present.
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It is a web on which machine reasoning can become
ubiquitous and powerful.
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It describes an emerging set of standards, markup
languages, and related processing tools.
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1968 – Internet used as a communications
network by DOD
1989 – Tim Berners-Lee (and others) at CERN
develop HTML
Early 1990s – Web browsers created to
interpret HTML
1996 – XML developed
1990s+ – Tim Berners-Lee & W3C continue to
pursue development the Semantic Web
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The agent would do this not by looking at pictures and reading
descriptions like a person does, but by searching through
metadata that clearly identify and define what the agent
needs to know.
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Metadata are simply machine-readable data that describe other
data.
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In the Semantic Web, metadata are invisible as people read the
page, but they're clearly visible to computers.
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Metadata can also allow more complex, focused Web searches
with more accurate results. To paraphrase Tim Berners-Lee,
inventor of the World Wide Web, these tools will let the Web -currently similar to a giant book become a giant database.
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The current Web remains largely unstructured
(e.g., company)
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Large amounts of information remain
unavailable
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Wikipedia describes the purpose of the Semantic Web as
follows:
Humans are capable of using the Web to carry out tasks
such as finding the Arabic word for “cat”, reserving a
library book, and searching for a low price on a DVD.
However, a computer cannot accomplish the same tasks
without human direction because web pages are
designed to be read by people, not machines.
The semantic web is a vision of information that is
understandable by computers, so that they can perform
more of the tedious work involved in finding, sharing
and combining information on the web.
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Four major components:
1. XML )eXtensible Markup Language)
XML is a markup language likehypertext markup
language (HTML), which you're probably somewhat
familiar with from surfing the Web. HTML governs
the appearance of the information you look at on the
Web. XML complements (but does not replace) HTML
by adding tags that describe data. These tags are
invisible to the people who read the document but
visible to computers.
2. Resource Description Framework (RDF)
RDF does exactly what its name indicates -- using XML
tags, it provides a framework to describeresources.
In RDF terms, pretty much everything in the world is
a resource. This framework pairs the resource (any
noun, like Anakin Skywalker or the "Star Wars"
trilogy) with a specific item or location on the Web
so the computer knows exactly what the resource
is. Clearly identifying resources keeps the computer
from doing things like confusing Anakin Skywalker
with Sebastian Shaw or Hayden Christiansen, or the
original trilogy with the One-Man "Star Wars"
Trilogy.
3.Ontologies
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There are two related tools for helping a
computer understand human vocabulary. An
ontology is simply a vocabulary that
describes objects and how they relate to one
another.
A schema is a method for organizing
information.
4. Agents read all the metadata found at different
sites.
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In our original example, we talked about buying "Star Wars"
DVDs online. Here's how the Semantic Web could make the whole
process easier:
Each site would have text and pictures (for people to read) and
metadata (for computers to read) describing the DVDs available
for purchase on their site.
The metadata, using RDF and XML tags, would make all the
attributes of the DVDs (like condition and price) machinereadable.
When necessary, businesses would use ontologies to give the
computer the vocabulary needed to describe all of these objects
and their attributes. The shopping sites could all use the same
ontologies, so all of the metadata would be in a common
language.
Each site selling the DVDs would also use appropriate security
and encryption measures to protect customers' information.
Computerized applications or agents would read all the metadata
found at different sites. The applications could also compare
information, verifying that the sources were accurate and
trustworthy.
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Semantic Web data is represented using a
technology standard called Resource
Description Framework (RDF).
RDF is a graph (web-like) structure that links
data elements together in a self-describing
way
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Supplemental components
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Uniform Resource Identifiers (URIs)
Web services
Inference rules
Service discovery
Semantic aware applications
Security and trust
XML and RDF schemas
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URI/IRI: URI is an acronym for Uniform Resource Identifier; a
compact string of characters used to identify or name a resource.
The URL to a web site (e.g. http://www.semanticfocus.com) is a
popular example of a URI. IRI is an acronym for Internationalized
Resource Identifier which is a form of URI that uses characters
beyond ASCII, thus becoming more useful in an international
context.
Unicode :Unicode is the universal standard encoding system and
provides a unified system for representing textual data. 1 million
characters can be encoded to specify any character in any
language without a single escape sequence or control code.
Before Unicode, there were several different encoding systems
which made communication and integration across borders a big
pain. (semanticfocus.com)
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XML: XML is an acronym for Extensible Markup
Language. With XML, we have a standard way to
compose information so that it can be more easily
shared. At the same time, it still affords the freedom
to structure that information however the heck we
want. It's kind of like HTML - only, you get to make
up your own tags and attributes. How cool is that?
Namespaces: Namespaces (aka XML Namespaces) are
integral to XML. Namespaces provide a means to
qualify the tags and attributes in an XML document
with URIs which then makes them truly unique on the
Web and thus, universal (among other things).
(semanticfocus.com)
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XML Schema XML Schema describes the structure of XML
documents just like DTDs, only better. An XML Schema is
known as an XML Schema Definition (XSD). Basically, if
you're going to use XML to invent your own document
structures, XSD provides the way to define your rules (like
guidelines) so that people and machines can understand
them, adhere to them, and integrate with them. XML
Query XML Query (aka XQuery) is a standardized language
for combining documents, databases, Web pages and
almost anything else. It is very widely implemented,
powerful, and easy to learn. XQuery is replacing
proprietary middleware languages and Web Application
development languages. XQuery is replacing complex Java
or C++ programs with a few lines of code.
(semanticfocus.com)
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RDF is a common framework for describing
resources.
It is primarily intended to represent metadata that
can be parsed and processed by machines rather than
just displayed to people. While the resources it
describes may be content or services that exist on the
Web, they don't have to be; they can be real-world
objects like you and I. Anything with identity can be
described in RDF and, in this sense, RDF is a good
candidate for recording and sharing knowledge on
the Web
With RDF, we can model information by describing
concepts in a way that is consistent enough for
machines to process uniformly. (semanticfocus.com)
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Ontology formally represents knowledge as a set
of concepts within a domain, and the
relationships among those concepts. It can be
used to reason about the entities within that
domain and may be used to describe the domain.
In theory, an ontology is a "formal, explicit
specification of a shared conceptualization".[1] An
ontology renders shared vocabulary and
taxonomy which models a domain with the
definition of objects and/or concepts and their
properties and relations (wikipedia.org)
“the common words and concepts (the
meaning) used to describe and represent
an area of knowledge" (Daconta et al.,
2003)
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Provide the repositories for meaning
interpretations
Provide a mechanism for defining the
relationship among different words and for
the Semantic Web, relationships among
different resources
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Consist of:
◦ Taxonomies
 “An organized set of terms.” (McComb, 2004)
 A classification and a tree (Daconta et al., 2003)
 Hierarchal, tree-like structures similar to
organizational charts
 Example
◦ Sets of inference rules
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Used to organize semantics
Next
Back
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Also known as software agents
Provide automation services
Should not be designed to replace humans or
to make decisions
Examples: Web spiders and crawlers
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scenario illustrates functionalities that can be
implemented based on Semantic Web
technologies
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Uniform Resource Identifiers (URIs)
◦ Provide a mechanism for identifying available
resources
◦ The super-set of URNs, URLs and URCs
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Web services
◦ Allow computer applications to communicate directly
with each other over the Internet
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Inference rules
◦ Define the relationships and rules between data
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Service discovery
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Semantic aware applications
◦ Allows applications to find ontologies and agents
◦ Applications that can make use of semantic
information
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Security and trust
XML schema
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RDF schema or OWL
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◦ Define the structure of XML documents
◦ Standardizes the communication between systems
◦ Can be used to define the language used in
ontologies and RDFs
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Improve e-business processes
Improve business-to-business (B2B)
communication
“assist human users in their day-to-day online
activities” (Antoniou & van Harmelen, 2004)
“build knowledge and understanding from raw
data” (Daconta et al., 2003)
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Improve knowledge management
Improve information retrieval
Automate tasking
Integrate data
Maximize customer value and profits
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Convert data to XML format according to
defined XML schemas
Expose applications as Web services
Build ontologies that specify semantic
meanings and the relationships between data
Create agents that make use of the semantic
data, automate search processes, and
automate other business processes
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Cost
Security
Nonstandard technology issues
Semantic precision
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http://www.foaf-project.org/
http://www.cs.rpi.edu/~hendler/
http://www.mindswap.org/
http://www.daml.ri.cmu.edu/
http://www.semanticwebsearch.com/query/