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

["Rick Jelliffe" <ricko@allette.com.au>]

 From: James Robertson <jamesr@steptwo.com.au>
 
>At 01:44 31/07/1999 , David Megginson wrote:
 
>>RDF is a general format for serializing entities and their
>>relationships -- sure it's useful for metadata, but it's main use (I
>>think) is as a more abstract layer on top of XML for exchanging
>>objects.
>
>Wouldn't a validatable format with a DTD
>be more useful for storing data?
>
>ie. plain vanilla XML?

RDF allows us to make the implicit relationships in vanilla XML
explicit.  This enables may enable explicit RDF tools and provides
a discipline or framework for data modeling.  

If you look at many RDF files (RPM for example) it is easy to 
think "so what...this does not have any type of information that
we have not been doing (e.g., in SGML) for years!"  

With XML we standardizing a syntax (and information set):
but that gave us no extra ability to model new kinds of data; 
it has allowed generic tools, more synergistic uncordinated 
development, and focussed attention away from peripheral 
implementation desicions.  RDF may be the same: the 
benefit is largely in the agreement and the explicitness
rather than in novelty.

>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 don't see that using RDF (serialized in XML) prevents 
verification.  My RDF DTD can be trivially augmented to 
allow particular DTDs, for example 
(http://www.ascc.net/xml/en/utf-8/schemas.html)

Verification is a tricky work, anyway.

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

The approach I have been suggesting here is this:
 1) make DTD/schemas that give you as specific markup
as possible, consonant with all your constraints;
  2) treat RDF as just another possible output formats.

Also there is the secret step:
  3) make sure that your specific DTD/schema has enough 
detail to allow generation of RDF as and when you need it.
For some kinds of flatter data, you may find it more convenient
to use RDF directly.

Rick Jelliffe



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