Re: [xml-dev] XML spec and XSD

["Simon St.Laurent" <simonstl@simonstl.com>]

Mukul Gandhi wrote:
> On Sat, Nov 7, 2009 at 7:38 PM, Simon St.Laurent <simonstl@simonstl.com> wrote:
>>  Leaving aside the question of how damaging W3C XML Schema has
>> been
> 
> I am not sure, how to respond to this. I guess this statement
> certainly hurts the XSD community, and it certainly does hurt me.

It's supposed to hurt XSD.  If you're that attached to XSD that 
complaints about XSD hurt you, I'm afraid you may be too attached to the 
technology.

> I don't know, how a technology (i.e, XSD..) that is capable of doing
> XML validation (and XSD does this well), and is implemented by number
> of XML products, which is implemented widely in XML applications (I
> can see uncountable XML instances been validated by XSD every day),
> can be damaging.

XSD is good for exactly two reasons:

* It starts conversation.

* It's widely deployed.

Unfortunately, it's also brittle, barely able to represent some common 
structures, offers extensibility mechanisms that aren't very extensible, 
and has lots of corners that aren't implemented consistently.  The 
XQuery folks encountered yet another set of problems in creating models 
based on it.

Worst of all, its W3C-blessed status often ends conversation, which can 
be poisonous for projects that would have done better with DTDs, RELAX 
NG, Schematron, a combination of those, no schema whatsoever, or 
something else entirely.

>> I suspect that counting validation as a fourth component might have eased
>> some problems all around, but that wasn't clear at the outset. That kind of
>> change seems like a project for XML 2.0, not for an edition change.
> 
> I'll be happy with XSD being specified in XML 2.0, if it can be.

Hopefully not.

>> (And, of course, I'd argue hard against any effort to incorporate W3C XML
>> Schema explicitly into XML 2.0....)
> 
> I am asking only for a simple reference in the XML spec, pointing to
> the XSD spec and ideally saying somewhere in the XML spec (2.0
> perhaps), that XSD is another validation technology from W3C similar
> to DTD.
> I still cannot think, why anybody can disagree to this. XSD and DTD
> both belong to W3C, and both are W3C recommendations, so I don't think
> why this simple modification to XML spec cannot take place.

Politically, of course it's possible.  And maybe the W3C, which is 
normally (though not always) fond of its works, will decide to add such 
a reference.

That would strike me as a continuation of the mistakes they've already 
made, but wouldn't be surprising.

-- 
Simon St.Laurent
http://simonstl.com/