Re: XML Schema becomes a W3C Recommendation

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

At 05:01 AM 5/3/01 -0700, XML Everywhere wrote:
>I doubt it.  XML newbies will take XML Schemas
>for granted, and it will be useful to them, just like DTDs.

The 'XML newbies' I've met who started with schemas immediately ran for 
tools, or gave up on XML altogether.

>I don't see anyone on this list spewing on about
>the beautifulness of DTDs yet they are used
>substantially more than any other XML-based
>schema, because all real parsers and other
>tools support DTDs.

Sure.  They're much more widely supported - and far easier to support - 
than any flavor of XML Schema.  They're also a legacy we inherited for 
better or worse, not an attempt to remake the face of markup.

Another nice feature of DTDs is that you can represent the resulting 
document in XML, if entity and attributes features are used.  It isn't yet 
clear how the "PSVI" concept can do that, and there are plenty of real 
issues surrounding how this fits into existing practice.

Are DTDs perfect?  No.  Are schemas any cleaner than DTDs?  Maybe in a 
limited number of cases they are, but the associated costs for the rest of 
XML are pretty ugly.

If all you ever want to do with XML is run it through your Microsoft/IBM 
parser and feed it into your programs, XML Schema is great.  If you have an 
interest in processing XML in lighter-weight environments or multi-step 
pipelines, or need to do things like compare different versions of the same 
language, I think the best I can say is that XML Schemas are a distraction.

>A standard schema language in XML that
>has wide-spread parser and tools support *is*
>exciting, even if it isn't everyone's favorite flavor.

I guess tornados, hurricanes, and even droughts are exciting in their own ways.


Simon St.Laurent - Associate Editor, O'Reilly & Associates
XML Elements of Style / XML: A Primer, 2nd Ed.
XHTML: Migrating Toward XML
http://www.simonstl.com - XML essays and books