xml-dev - RE: RDF Sample, ICAO Airport Codes

["Didier PH Martin" <martind@netfolder.com>]

Hi David,

After reading your comments it appeared to me that tacitly you have this
model (please correct me if this is wrong, I just guessed it from trying to
understand your position)

a) XML DTD based documents are more documents in the classical sense like
for instance a report, a book, etc...
b) RDF based document are more for data exchange and more particularly for
data base data exchange.

The former allows you to add meta-information in your documents by adding
meaningful tags in your text. The latter, because of a more formal schema
definition, and also because rdf has to the notion of record (implicitly),
it is more suited to data base exchange which, by the way, is also record
based and these records are defined by a formal schema.

Is this what you have in mind?

regards
Didier PH Martin
mailto:martind@netfolder.com
http://www.netfolder.com
-----Original Message-----
From: owner-xml-dev@ic.ac.uk [mailto:owner-xml-dev@ic.ac.uk]On Behalf Of
David Megginson
Sent: Saturday, July 31, 1999 6:50 AM
To: xml-dev@ic.ac.uk
Subject: Re: RDF Sample, ICAO Airport Codes


James Robertson writes:

 > Wouldn't a validatable format with a DTD
 > be more useful for storing data?
 >
 > ie. plain vanilla XML?

Why not just ASCII?

 > Otherwise, aren't we advocating abandoning XML for a
 > another format? One that loses the ability to be
 > verified, except with the use of custom-written software.

I could write a DTD for my airport example if I wanted, but I see
little value; instead, I'd probably use the W3C's proposed RDF-schema
language, since it works at the right semantic level.

Besides, while DTDs are useful, they allow validation of only a tiny
subset of business rules: as I mentioned in a recent discussion within
the W3C, a DTD can ensure that HTML <h1> doesn't appear within <p>,
but it cannot ensure that the text in it is actually a descriptive
section title.

 > In other words, if RDF is intended for storage of data,
 > what's XML for?

If XML is intended for the representation of documents, what's ASCII
for?

Good application design (like good system design) requires a layered
approach:

- if a lot of people need to extract a stream of characters from many
  different byte encodings, you invent a standard (like Unicode) so
  that they can all refer to a common set of characters in the
  abstract;

- if a lot of people need to extract a tree structure from a
  stream of characters, you invent a standard (like SGML or XML) so
  that they can all use standard software tools rather than rolling
  their own;

- if a lot of people need to relabel the tree nodes with
  universally-identifiable and unique names, you invent a standard
  (like Namespaces in XML or Architectural Forms) so that they can all
  use standard software tools rather than rolling their own;

- if a lot of people need to extract a set of objects from the tree,
  you invent a standard (like RDF or XMI) so that they can all use
  standard software tools rather than rolling their own.


All the best,


David

--
David Megginson                 david@megginson.com
           http://www.megginson.com/

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