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- From: David Brownell <david-b@pacbell.net>
- To: David Megginson <david@megginson.com>
- Date: Wed, 01 Sep 1999 15:08:04 -0700
As someone said (and it wasn't Bill Joy who said it first,
despite what someone said here the other day!) there are
only three interesting numbers in computer science: zero,
one, and many (including an infinity).
If the XHTML WG doesn't want one namespace (like us rational
folk on this list :-), and we don't like to see an unbounded
number of namespace IDs ...
Perhaps the right answer is zero: just take the namespace
URI out of the XHTML spec completely.
- Dave
p.s. I think the actual formula is a bit less than N-squared;
N, plus N-1 combinations of the namespaces that are "all
but one of them", and so on. Regardless of what the real
formula is, it's clearly a nonlinear growth.
David Megginson wrote:
>
> Hunter, David writes:
>
> > In other words, any application which is working with XML can just
> > look for that namespace and say "oh, this element is using XHTML.
> > I'll hand it off to the XHTML application to process". If we use
> > separate namespaces, then any application which may have XHTML to
> > process will have to know about all of those namespaces. Perhaps
> > not a big deal, if only those three namespaces are ever used, but
> > perhaps a huge deal if more flavours of XHTML are created, or the
> > namespaces are versioned.
>
> In fact, there could end up being an exponential explosion of
> XHTML-related Namespaces, depending on how the HTML WG intends to
> proceed (it's not explicit in the publicly-available XHTML documents,
> and I hear contradictory things from the WG members).
>
> What happens when a vendor wants to create a new element that will
> appear in, say, an HTML paragraph? Obviously the new element itself
> (such as <ms:spreadsheet> or <ra:videoclip>) will have to be in a
> different Namespace -- that's the whole point -- but will the
> containing paragraph have to be in a different Namespace as well? In
> other words (assuming that XHTML is the default Namespace) can we have
>
> <p>Today, President Clinton visited the finger lakes.
> <ra:videoclip src="clinton.ram" />.</p>
>
> <p>Economic indicators are down.
> <ms:spreadsheet src="stuff.xls" />.</p>
>
> or does it have to be this?
>
> <ra:p>Today, President Clinton visited the finger lakes.
> <ra:videoclip src="clinton.ram" />.</ra:p>
>
> <ms:p>Economic indicators are down.
> <ms:spreadsheet src="stuff.xls" />.</ms:p>
>
> (And, of course, an <ms:li> to hold the <ms:p>, and an <ms:ul> to hold
> the <ms:li>, and an <ms:body> to hold the <ms:ul>, and an <ms:html> to
> hold the <ms:body> -- it will always necessarily bubble to the top
> <html> element).
>
> If the HTML WG takes this (terrifying) path, then what happens when a
> Web author wants both extensions in the same paragraph? <ra:p>
> doesn't allow <ms:spreadsheet>, and <ms:p> doesn't allow
> <ra:videoclip>, so it looks like she's somehow expected to invent yet
> another Namespace herself:
>
> <my:p>Today, President Clinton visited the finger lakes.
> <ra:video-popup src="clinton.ram" />. Economic indicators are
> down. <ms:spreadsheet src="stuff.xls" />.</my:p>
>
> My math sucks, but as far as I can figure out, that means that the
> number of possible HTML-related Namespace URIs will end up being not
> only three, but about two to the power of the number of parties who
> decide to create extensions (and that's assuming that each vendor
> creates only a single Namespace).
>
> That means that if only 20 parties create extensions for use in XHTML
> documents, we will necessarily end up with over 1,000,000 variants of
> the <html> element.
>
> That's an awful lot more than three extra lines of code, whatever the
> software infrastructure.
>
> All the best,
>
> David
>
> --
> David Megginson david@megginson.com
> http://www.megginson.com/
>
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