Semantic Web Technologies
Definition: Semantic Web Technologies is an umbrella term used to describe both the infrastructure and
services provided by the Semantic Web, a framework that allows software applications to
automatically discover, access and execute web services.
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One of the largest problems in the development of IT systems within an enterprise is
integration between applications. Even today, there are few integration standards used
by software developers to allow their applications to effectively communicate with third
party software. The inevitable result is that
enterprise IT systems are cobbled together,
inefficient hulks – and IT budgets are drained in an effort to find some way of integrating
multiple disparate systems.
Development of SOA and Web Services
In an effort to alleviate these problems and their associated costs, software
developers and organisations such as the World Wide Web Consortium (W3C) worked to
design a number of standards by which software applications could become interoperable.
The result of this was the development of
Service-oriented Architecture (SOA), a
collection of interoperability standards that allow loosely coupled software services
to interconnect, regardless of platform or operating language.
Furthermore, markup languages such as
XML (and XML-based formats such as SOAP and WSDL)
extended this ability to include web services, allowing applications to exploit services over the Internet.
Development of the Semantic Web
Though the development of XML and its various formats was an important advance in the
development of interoperable web technology, the limitations of the language are all too evident.
The primary problem is that XML is not descriptive enough about the information it
describes for it to be adequately computer-understandable. While the foundations for
connectivity have been laid out in SOA standards and XML, there remains the simple
problem that, though computers can discover services and connect to them, they have
no way of understanding what these services actually do. For that we require a new language.
Semantic Web Technologies
In an effort to enable computers to understand semantic web services there have been
developed several technologies that will pave the way, including
Resource Description
Framework (RDF) and Web Ontology Language (WOL).
RDF is a metadata model (typically based on XML) that assigns data with a semantic
metadata description that can be understood by computers. The
RDF model is based on the RDF ‘triple’, a method of describing data using a ‘subject-predicate-object’ expression.
For example, a computer would have no way of understanding the statement ‘The couch has
the colour red’, as computers cannot use semantics to draw conclusions as to its meaning.
However, by describing the statement as ‘subject-predicate-object’ it is possible to tell
the computer what the statement means:
‘The couch’ = subject
‘has the colour’ = predicate
‘red’ = object
Based on these metadata, a computer could now infer the meaning of the complete statement,
rather than simply recognising the words themselves.
Applications in Web Services
The various semantic web standards (such as RDF and OWL) add an extra layer on top of
syntactic data to provide computers with a method to understand the semantics of information.
The implications this will have for web services are potentially enormous.
By providing computers with the means to understand the information held on the Internet the
online experience could become a single mashup – that is, an application that draws data from
multiple locations and presents them seamlessly in a single application. Computers could scour
the Internet for relevant data and present it automatically to our desktop computers.
Clearly this would be a great development in personal computing, allowing users to set their
personal preferences and entrust the computer to gather information they’re interested in.
However, it could have an even greater impact on business.
The Internet represents the largest repository of information on earth. Unfortunately, the
volume of data and the way in which it is presented prevents us from effectively
capitalising on that information at present. The development of the Semantic Web will
enable computers to automatically
gather valuable data from hundreds – or even thousands – of
web services, presenting them to the user for analysis.
With developments in semantic web technology, it seems the days of manual browsing could be
numbered. In the future, there may be no need to deal personally with the Internet at all.
We will instead use semantic web applications as our window to the web.
Further information regarding semantic web technologies can be found at the
University of
Southampton (pdf), the Open University and
CETIS.
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