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I think we hit a key point here.
On Thu, 2002-05-09 at 14:06, Matthew Gertner wrote:
> > XML is a wonderful foundation for building certain kinds of
> > information
> > interchange systems, and a key tool for making it clear that
> > information
> > interchange is in fact possible. XML is not an ideal tool for
> > exchanging all kinds of information, however. The metadata costs of
> > working with a text format spiral rapidly as more complex types than
> > element structures and attribute annotations are applied.
>
> Who is talking about adding more complex types than elements and attributes?
You are!
> I thought we were just talking about defining the datatype of attribute
> value and element leaf nodes more precisely than simply saying that they are
> "PCDATA".
And that's precisely where we diverge. XML 1.0 types use markup to
identify structures in content. For example there may be information of
type "quantity" that gets marked up as a "quantity" element. The
definition of such things is notably called an "element type
definition".
You're unhappy with the meager information these types provide, and want
to pile on an extra layer of metadata that connects the element name
"quantity" to something else - an integer, most likely.
From my perspective, you're crossing a line there. While integers
aren't particularly harmful in and of themselves, that's the leading
point of a much much larger wedge. As that wedge moves deeper (see for
example, XQuery/XPath) what was once a quantity is now an integer,
perhaps constrained with min and max values, perhaps given another name
to identify it as a particular type of integer.
Once you have that much metadata about "quantity" you can do an awful
lot of things you couldn't do when "quantity" was a textual type
identifer applied to text. You can optimize the representation of that
integer - which is what I've proposed - and you skip an awful lot of
intermediate processing to reach that number.
If all you really want is the number, why monkey around with text? You
can still mix your numbers with text if you want - storing text in
optimized binary formats is hardly a new idea - and you can do new
things like build editors which have a much more direct connection to
the information.
The more the XML world tries to accomodate a programmer's view of
information, the more I think we ought to just hand them that, and take
it seriously. XML's broken down some important walls. There are walls
ahead where I don't think it will be nearly as effective.
--
Simon St.Laurent
Ring around the content, a pocket full of brackets
Errors, errors, all fall down!
http://simonstl.com
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