Namespaces and XML validation

[Peter Murray-Rust]

At 12:27 10/08/98 -0700, Murray Altheim wrote:
[...]
>
>Peter,
>
>You speak with great optimism about the compatibility issues of the 
>current namespace draft. I think it would be sobering for anyone to read

I am known to be overoptimistic.  It occasionally has virtues. I think a
lot of it comes from being an experimentalist - if most things work most of
the time we are doing very well. I am also a believer in the value of
kludges and (occasionally) communal self-discipline. 

I compare XML with C++. I went through the midnight blood with that... C++
now works - it's not pretty, but it works. It paved the way for Java. So I
see XML1.0 working and being made to work. Perhaps it's just a station on
the road... who knows in 5 years time?

>over the working group archives to see that compatibility is not a given.

These are not generally available...

>In all but trivial DTDs namespaces have been shown to be incompatible with
>XML 1.0 validation (or at very least more manual effort than would be 
>worth the trouble*). The solution for validating moderately complex 
>structures using qualified names without wholescale rewriting of existing
>DTDs has not yet been found. It is a given that any such alternative 
>validation solution would be inherently incompatible with existing the
>validation methodology (ie., the SGML-compatible declaration syntax in
>XML 1.0). This (as I mentioned to Charles Frankston) is not a matter of
>imagination but of compatibility and interoperability.

I think we are in the experimental phase of XML where we are asking the
wider world whether validation is valuable. To many established SGML people
the lack of validation is near heresy. [In the same way I suspect many
people couldn't envisage a useful OO language without multiple inheritance.
But Java works. Only very occasionally do I think "it would be nice to have
MI at this point". I suspect it will be the same for XML. As I have often
(probably boringly) said, I think my community is far more interested in
semantic than syntactic validity. (Actually they probably don't care about
either much...)

>
>We can all hope that some new schema language solves all the problems 
>that arise in XML's nascent life, but we cannot do so at the expense of
>incompatibility with XML 1.0. Unfortunately, I do not believe 
>compatibility with XML 1.0 validation is on the minds of all participants
>and see a schism arising: XML 1.0 compatible, and XML-subset compatible.

Subset? 

	P.

Peter Murray-Rust, Director Virtual School of Molecular Sciences, domestic
net connection
VSMS http://www.nottingham.ac.uk/vsms, Virtual Hyperglossary
http://www.venus.co.uk/vhg

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