Re: Semantic Web: Beyond Metadata

From: J. R. Molloy (
Date: Fri Oct 19 2001 - 09:34:57 MDT

From: "Robert Coyote" <>
> WHat role could XML play in this?

Probably an extensive role. <g>

On 29 October, Tatsuya Hagino gives a talk on the Current Situation and
Perspective of Semantic Web and XML at the INTAP Semantic Web Conference in
Tokyo, Japan. (News archive)

Semantic Web on XML
You probably have a lot of people using XML by now. You should have someone
looking at the next level - RDF. Tell them not to worry about the syntax, but
check out the model. This is a question of looking the data your company is
storing and transferring, and making sure that it can be represented in that
simple circles-and-arrows RDF way. This is very simple. An important trick is
that you use URIs to identify the arrows as well as the circles. Doing this
homework will ensure that you have a well-defined data model, which will allow
you data to be combined, merged with any other RDF-model data. It will mean
you will be able to multiply the power of separate application areas by
running RDF queries and new RDF-based applications across both areas. It will
mean that you will be there with talent which understands the basic model as
the Semantic Web becomes all-important.
Other things to watch: SVG - Scalable Vector Graphics - at last, graphics
which can be rendered optimally on all sizes of device. The user interface
world is rapdly becoming comptent at voice input and output an W3C has
standards in that area coming along. XML Signature will let you to digitally
sign XML documents - find out how. But in general, always check out the W3C
home page for what's new.

XML and Semantics
The eXtended Markup Language is accepted as THE emerging standard for data
interchange on the Web. XML allows authors to create their own markup (e.g.
<AUTHOR>), which seems to carry some semantics. However, from a computational
perspective tags like <AUTHOR> carries as much semantics as a tag like <H1>. A
computer simply does not know, what an author is and how the concept author is
related to e.g. a concept person. XML may help humans predict what information
might lie "between the tags" in the case of <trunk></trunk>, but XML can only
help. For an XML processor, <trunk> and <i> and <bookTitle> are all equally
(and totally) meaningless. Yes, meaningless.
This has direct consequences for economy on the web.

The XML Cover Pages
XML and 'The Semantic Web'
By: Robin Cover
Two important technologies for developing the Semantic Web are already in
place: eXtensible Markup Language (XML) and the Resource Description Framework
(RDF). XML lets everyone create their own tags -- hidden labels such as or
that annotate Web pages or sections of text on a page. Scripts, or programs,
can make use of these tags in sophisticated ways, but the script writer has to
know what the page writer uses each tag for. In short, XML allows users to add
arbitrary structure to their documents but says nothing about what the
structures mean . Meaning is expressed by RDF, which encodes it in sets of
triples, each triple being rather like the subject, verb and object of an
elementary sentence. These triples can be written using XML tags. In RDF, a
document makes assertions that particular things (people, Web pages or
whatever) have properties (such as 'is a sister of,' 'is the author of') with
certain values (another person, another Web page). This structure turns out to
be a natural way to describe the vast majority of the data processed by
machines. Subject and object are each identified by a Universal Resource
Identifier (URI), just as used in a link on a Web page. (URLs, Uniform
Resource Locators, are the most common type of URI.) The verbs are also
identified by URIs, which enables anyone to define a new concept, a new verb,
just by defining a URI for it somewhere on the Web... this is not the end of
the story, because two databases may use different identifiers for what is in
fact the same concept, such as zip code. A program that wants to compare or
combine information across the two databases has to know that these two terms
are being used to mean the same thing. Ideally, the program must have a way to
discover such common meanings for whatever databases it encounters. A solution
to this problem is provided by the third basic component of the Semantic Web,
collections of information called ontologies.

XML and the Second-Generation Web
As XML spreads, the Web should become noticeably more responsive. At present,
computing devices connected to the Web, whether they are powerful desktop
computers or tiny pocket planners, cannot do much more than get a form, fill
it out and then swap it back and forth with a Web server until a job is
completed. But the structural and semantic information that can be added with
XML allows these devices to do a great deal of processing on the spot. That
not only will take a big load off Web servers but also should reduce network
traffic dramatically.

--- --- --- --- ---

Useless hypotheses, etc.:
 consciousness, phlogiston, philosophy, vitalism, mind, free will, qualia,
analog computing, cultural relativism, GAC, Cyc, Eliza, cryonics, individual
uniqueness, ego, human values, scientific relinquishment

We move into a better future in proportion as science displaces superstition.

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