Overloaded URIs (was Re: XLink: behavior must go!)
John E. Simpson
simpson at polaris.net
Sun Jun 13 20:21:55 BST 1999
At 12:43 PM 06/13/1999 -0500, WorldNet wrote:
>Okay, two or more documents interacting with one another
>are determined to have exact element and or attribute names so the
>namespace identifier then acts as a differentiator. What next?
>Meaning, I thought namespaces were going to be like libraries
>of contextual data definitions?
It's understandable why someone might think so. But all a namespace is, in
my understanding, is an abstract bucket in which can be placed all the
"nouns" pertaining to a single XML universe of discourse. So if your
documents never stray from a single such universe, they don't need namespaces.
I think XSL is an interesting application in this case because the "nouns"
it's intended to process will almost never be from the XSL universe itself.
Some of XSL's own "nouns" (like apply-templates) are so distinctive in
their own right that the likelihood of name clashes with the processed
vocabularies, whatever they might be, is fairly small. Nonetheless, in the
XML spirit of no-such-thing-as-a-reserved-word, an XSL processor expects
you to declare that "in the context of this document [which just happens to
be an XSL stylesheet], all XSL-specific nouns will be expressly associated
with the XSL namespace." There's nothing magical about this. You could if
you wanted associate the "xsl:" prefix with some *other* namespace. That
would have to be almost calculatedly misleading on your part, though. :)
>>The URI scheme has been
>> suggested as a familiar way to accomplish this. I still haven't made up my
>> own mind about it, but (to me) its chief flaw is that it *suggests* to a
>> namespace-unaware human reader that There Is a "There" There.
>And I've become such an 'Accidental Tourist'.
Anne Tyler, well, I'm not so sure I can force-fit her into an XML namespace
discussion myself. But to return to the Gertrude Stein, er, namespace of
"there is no there there," for a given XML document instance, a rose is not
a sun:rose is not a midler:rose. That's all that namespaces are meant to
keep sorted out.
John E. Simpson | The secret of eternal youth
simpson at polaris.net | is arrested development.
http://www.flixml.org | -- Alice Roosevelt Longworth
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