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   Re: [xml-dev] Objections to / uses of PSVI?

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On Wed, 2002-05-15 at 06:53, Ronald Bourret wrote:
> > There are lots of people who want to slap their existing typed data into
> > markup without switching from a OOP or RDBMS notion of types to a
> > recognition that "element type declarations" are what they say they
> > are.  To me, this suggests these people haven't thought through why
> > they're using markup in the least, and that seems plain old dangerous.
> I disagree. I think they have thought through what they want to do.

I think you must hang out with a wiser crowd than I do.

> They
> want, for example, to be able to validate that a quantity is a (string
> representing an) integer and not "abc". This strikes me as perfectly
> reasonable.

For validation only, fine.  I don't mind checking that something's an
integer.  Where I think they lack imagination is their insistence that
because it _is_ an integer in XYZ language, it _is_ an integer in
markup.  Then the markup technologies have to deal with such notions,
and suddenly things look very different.

Think about retrofitting the DOM or especially SAX to represent the
PSVI, and that difference is pretty plain.

> I think where the XML Schemas data types have missed the boat is in
> their degree of complexity, as Amy Lewis points out. If you want
> interoperability, you can't go much beyond saying that a number is an
> integer. It is the up to the recipient of the document to decide (a)
> whether they can represent that number in whatever language / system
> they are using and (b) what data type they choose to represent it in.

"It is up to the recipient" is fine by me - but that's not what I hear
discussed in ~90% of discussions of XML typing and schemas outside of
this list. 

> I agree about partial validity. What's partial well-formedness?

It's mostly an editing phenomenon where, for instance, there are lots of
start-tags but no end-tags.  It's a common scenario in HTML and
definitely in SGML, but something that kills XML.  It's another area
that could use some tools, and I think Rick's working on it.

It does happen in data situations most certainly, but it happens mostly
in cases where humans are actively "marking up" a document rather than
in cases where a program is just serializing whatever.

Simon St.Laurent
Ring around the content, a pocket full of brackets
Errors, errors, all fall down!


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