X-Schema

Hunter, David dhunter at Mobility.com
Wed Jun 16 17:02:39 BST 1999


David Megginson [mailto:david at megginson.com] writes:
> Paul Prescod writes:
> 
>  > I am genuinely interested in improving XML usability, however, so I
>  > would like to hear counter-arguments.
> 
> In my opinion, the best counter argument is that you can include
> structured documentation as part of the schema itself.  In a DTD, an
> awful lot of useful information is stashed away in comments, and has
> to be copied into documentation using cut-and-paste.
> 
> 
> All the best,
> 
> 
> David

If I could throw in a point which is scarily reminiscent of the DOM+CSS vs.
XSLT and XSL-FO debate, I'm a little worried that we're inventing two
languages which do exactly the same thing.  Or rather, we've <em>got</em>
one language, and we're inventing <em>another one</em> to do the same thing.
Now in most cases, having multiple languages is a Very Good Thing.  (e.g. I
happen to love C++, but use Visual Basic almost exclusively for what I do.
And I'm itching to use more Java, so I will when I get the chance.)

However, in this case, when Schemas become a recommendation are all XML
parsers going to have to know how to validate against DTDs as well as
Schemas?  Are we going to have some parsers that only understand DTDs and
some that only understand Schemas?  Are DTDs going to become obsoleted, if
Schemas can do everything they can do and more?  If so, what happens to all
of the existing XML documents with DTDs?  Do we re-write them?

Don't get me wrong, I happen to like Schemas much better than DTDs, and the
data typing alone makes them a better choice for many things.  I'm just
wondering if we wouldn't be better off adding the extra functionality to
DTDs, instead of creating a new language.  Are there technical reasons why
we can't?  (Does it have something to do with SGML compatibility?  If so I'd
be willing to shut up right now.  :-)

David Hunter
david.hunter at mediaserv.com
MediaServ Information Architects
http://www.MediaServ.com

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