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At 2:26 PM -0500 11/25/03, Betty Harvey wrote:
>If DTD's are what we work with, I would agree that we have made it easier.
>However, I believe that DTDs may be on their deathbed and are now
>considered deprecated or legacy. The reality is that most organizations
>are using schema's for all "new" projects. The U.S. Government recommends
>the use of W3C Schemas
>
I do not consider DTDs at all deprecated or legacy. I know the
opposite opinion is out there, but it's wrong. I wrote about this in
Chapter 24 of Effective XML (not online yet, sorry), and I have been
careful in all my talks about schemas to make sure that everyone
knows they are not a replacement for DTDs.
I also see a lot of evidence that the W3C XML Schema Language is
losing the schema wars to RELAX NG. Many high profile groups have
chosen to adopt RELAX NG for their schema needs rather than the W3C
XML Schema Language. The prime reason for the W3C XML Schema
Language's current and, I think, transitory prominence is merely the
W3C imprimatur. Among developers who realize they have a choice, the
choice is increasingly likely to be RELAX NG.
I also suspect that the majority of XML doesn't have any any schema
at all in any language. Certainly very little of my own does, and
what does is more likely than not invalid. The assumption that some
form of schema is necessary is a common flaw in many developers'
initial assumptions about XML. The real innovation of XML was not
making the DTDs simpler. It was making them optional. Documents that
do not have document type declarations are incredibly interoperable,
with almost no room for parser differences in interpretation. All the
different possible parsings of an XML document arise only in the
presence of a DTD or some other schema. Without a schema, the
document is simply what it is, no ifs, ands, or buts.
--
Elliotte Rusty Harold
elharo@metalab.unc.edu
Effective XML (Addison-Wesley, 2003)
http://www.cafeconleche.org/books/effectivexml
http://www.amazon.com/exec/obidos/ISBN%3D0321150406/ref%3Dnosim/cafeaulaitA
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