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RE: Namespaces, W3C XML Schema (was Re: ANN: SAX FiltersforNamespaceProcessing)
- From: "David E. Cleary" <email@example.com>
- To: xml-dev <firstname.lastname@example.org>
- Date: Tue, 31 Jul 2001 15:59:41 -0400
> By introducing unqualified child elements, XML Schemas has done for
> well-formed document processing (with respect to namespaces) what
> attribute defaults did to well-formed document processing (with respect
> to DTDs). This is not necessarily something to be proud of.
XML Schema has not introduced unqualified child elements. Also, it was not
in XML Schema's charter to only support a subset of XML. Unless there were
technical reasons something couldn't be done and there was a plausible
explanation for it, it had to be supported. Whether it is good or bad
practice, something I'm not arguing, is irrelevant. People were free to do
it before Schema and people are still free to do it after Schema.
> The net result is that, in the absence of a schema/DTD (or hard-coding
> schema/DTD information in your application), you can't correctly
> interpret the document. In other words, your document is not portable.
If every element stands on its own, then I agree with you. But this is not
true. You still have the hierarchy of the XML to interpret the element. All
Schema buys you is an easier way to determine this, and that is only after
the APIs catch up. Don't take this as arguing people should use unqualified
elements. I'm just arguing that Schema isn't to blame for this.
There are two reasons why someone would do this:
1. They have a reason to.
2. They do not know what they are doing.
Simon's filter will help those in camp 2, but will most likely cause serious
side-effects for those in camp 1.