- From: Eric van der Vlist <vdv@dyomedea.com>
- Date: Thu, 20 Sep 2001 20:34:55 +0200
- To: Rich Salz <rsalz@zolera.com>
- Cc: Marc Hadley <marc.hadley@sun.com>, Jacek Kopecky <jacek@idoox.com>, xml-dist-app@w3.org
Rich Salz wrote:
> Also, isn't it Official
> W3C Opinion that DTD's are declasses -- schema is the way to go?
>
This is a hoax that's difficult to kill!
W3C XML Schema covers only one third of the functionalities of the DTDs.
To simplify, DTDs include 3 different areas:
1) Schema (for which W3C XML Schema may be seen as an alternative).
2) External parsed entities (for which XInclude may be seen as an
alternative).
3) Internal parsed entities for which, AFAIK, there is no official
replacement project).
Also, we must differentiate internal and external DTDs.
Internal DTDs cannot be replaced by W3C XML Schema which doesn't provide
this kind of facility.
The problem with external DTDs (and with external parsed entities) is
that they create a dependency between the file that is transmitted and
external resources.
This can be an obvious problem when these resources are located using
relative URIs, this can also be a problem when they are defined through
absolute URIs since the response to the request to reference them often
varies in the time and can also depend on the headers used in the request.
A resource can be updated or be unavailable. In both case, the infoset
of the document (and its meaning) will be affected and this, IMHO, is a
serious problem that would need to be addressed if DTDs were allowed in
SOAP requests.
My 0,02 Euros.
Eric
--
See you in Scottsdale, Arizona.
http://xmlconnections.com/xml/xmlfall2001/speakers.asp#evandervlist
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Eric van der Vlist http://xmlfr.org http://dyomedea.com
http://xsltunit.org http://4xt.org http://examplotron.org
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Received on Thursday, 20 September 2001 14:34:54 UTC