Star rising for the Semantic Web

by Edd Dumbill

One of the most striking differences between the href="http://www2002.org/">Eleventh International World Wide Web
conference (WWW2002) and its previous edition in 2001 is the large
increase in activity related to the Semantic Web. The premise of Tim
Berners-Lee's brainchild is that the Semantic Web fulfils the other half of
his dream for the Web: for computers to be able to communicate generally over
the web, thus making the vast amount of information out there a lot more
useful to human beings.



Let me give one of the more common examples: currently if you wish to book
a flight on the web, you need to look up several sources of information: your
own schedule, flight timetables, connecting transportation, frequent flyer
details. Through various means you juggle all this information and come up
with some candidate flights, which you then attempt to purchase. If all this
information were available to a program on your computer, it would be a
relatively simple matter for the computer, your "user agent", to come up with
the likely flights for you, just requiring you to choose between them.



In order to make this sort of thing possible in the general case, a lot of
infrastructure needs to be put into place. First, it will help if all the
sources of information are able to present the same syntax to the user agent.
The work to enable this is almost done, in the shape of XML and RDF: the W3C
RDF Core Working Group are now well advanced in their revision of the
original RDF specification, aimed at tidying up the first edition from 1998.
Second, all the sources of data need to be able to name and describe the
various shapes their data can take. This is where the semantics start to come
in. The fancy word for such descriptions is "ontologies" (practically a
synonym for "schema", but that word is somewhat overloaded by SQL and W3C XML
Schema these days). The W3C's WebOnt Working Group is charged with this piece
of the puzzle, and they're building on existing work such as href="http://www.daml.org/">DAML. As somebody remarked to me, there were
a surprisingly large number of papers focusing on ontologies at the WWW2002
conference. There is a lot of practical research work going on in the
field.




One other vital element is that of trust. If your computer's going out to
fetch flight schedules, you want to be able to trust it to return accurate
information about such a high cost purchase. If it is sending your personal
information out in order to do this, you also want to know it's being done
securely. Enter the work on XML Encryption and Signatures. This effort is in
a pretty mature state for XML itself, but work needs to be done to integrate
this technology with other Semantic Web technologies to create the "web of
trust" that will enable users to decide how trustworthy a source of
information is.



That Semantic Web development work is progressing is all well and good,
but clearly what matters to developers and users is the question of when all
this will emerge from the research lab. That it is research is undeniable,
something that makes many normal developers think it dusty and obscure. That
it is incomplete and emerging is also true, something that makes some experts
in knowledge management think it ill-conceived. However, Berners-Lee met with
these kinds of reactions on the creation of the Web itself: it isn't
difficult to imagine the same doubts being raised in the early 90s. Simply
because he pulled it off once is no indicator he can repeat the feat, but
other factors are pointing to a turning in the tide of opinion about the
Semantic Web.



Despite the official positions of their employers, I have noticed several
prominent members of the Web community taking a harder, more serious look at
the Semantic Web. They may not be on the road to Damascus just yet, but
there's a rise in credibility of the Semantic Web idea not seen last year.
Another significant activity is the creation of a European research project
specifically focused on delivering useful software components, which will
take into its sphere the excellent Java and C RDF frameworks, href="http://www.hpl.hp.com/semweb/">Jena and href="http://www.redland.opensource.ac.uk/">Redland.



The Semantic Web effort is not just Tim Berners-Lee. There are now a large
number of people committed to the idea and its development. While work
continues in research and specifications, these people also need to start
finding ways of making Semantic Web technology useful in everyday computing
scenarios. This is the critical issue: the Web succeeded because of the
problems it solved, and the aptness of the solution. The developers of the
Semantic Web need to see past their academic surroundings to address, however
simply, some of today's information management problems.



Related content:





What's your view on the Semantic Web? Share your opinion in the forum.