Re: Mechanism, not policy [was: Attribute uniqueness...]

David Carlisle wrote:
> 
> > Huh? Joe's statement isn't the literal interpretation; it's
> > the absolutize interpretation, no?
> 
> Joe answered already, but this:
> >    > It explains the fact that ..\light lights a bulb in one case and a
> >    > fuse in another as being an _intentional_ result of the decision to use a
> >    > context-dependent reference in the first place. The answer "if it hurts
> >    > when you do that, don't do that" really is consistant with this model.
> 
> Is essentially the rationale for the literal interpretation.
> 
> If someone uses "../light" as a namespace name then they either don't
> care what if anything it refers to (this is the case for any namespace
> processing), and if they intend, after namespace processing, to use
> the namespace name to reference some resource then they presumably
> _intended_ the resource to depend on context.

Huh? I thought Joe was saying:

	If someone writes a namespace declaration ala
		xmlns="../light"
	then the fact that this denotes
	a namespace name of http://example.com/switches/light
	given one base URI, and a namespace name of
	http://example.com/weights/light given another base URI,
	is as intended.

> This is what the literal interpretation gives you.
> 
> Saying that the namespace name produces different resources depending
> on context is exactly the same (by definition) as saying a relative
> URI will, depending on the context dereference a different resource.
> 
> In the absolute interpretation the namespace name is for some
> unexplained reason not taken as the supplied string but as
> the absolute URI that it resolves to. This means that despite
> the author having specified a relative URI the same resource is
> always located by the namespace name in all contexts.

Not so; see elaboration above.

> This is
> just bizarre, if that had been the intention then an absolute URI
> could have been used in the first place.
> 
> Basically the absolute proposal comes from a fundamental
> misunderstanding of the namespace rec:

I don't think so...

> That a namespace with name a particular URI _is_ the resource
> identified by that URI.

That's a tautology, no? By analogy:

	A person with a name "Fred Smith" *is* the thing identified
	by "Fred Smith".

(subject to definite descripton errors... i.e. two persons
named "Fred Smith" in the universe of discourse...
the phrase "the resource with a particular
URI" is problematic; it's always safe to talk about "the resource
identified by a URI")

> That is just false. If it were true then you would need the forbid
> option as relative URI don't refer (in themselves) to resources.

I'm getting lost; it a very narrow technical sense, you're right:
relative URI references refer to absolute URIs, and absolute URIs
refer to resources.

> If
> the namespace with _was_ the resource with URI equal to the namespace
> name then clearly xmlns="foo" would be undesirable as the namespace is
> (at most) one thing

no, in the absolute interpretation, that namespace declaration denotes
a different namespace name (absolute URI) and hence refers to
a different thing, depending on the context.

Just like
	<a href="foo">...</a>
shows different target URIs at the bottom of your browser
window, depending on the base URI of the document where
your browser found it.

> but the relative URI refernce "foo" identifies
> different things depending on context.
> 
> But that is not the situation. Namespaces have names which are URI
> references.

In the absolute interpretation, namespace names are absolute URIs
(plus optional fragment identifiers).

> That does not mean that they are the resources identified
> by those references, anymore than (to reuse an example I used before)
> than machines in nag which are named after english towns _are_ towns.
> 
> The namespace name in
> 
> <x xmlns="http://www.w3.org" />
> 
> just is the URI of the W3C home page. That resource doesn't aquire any
> properties of a namespace just because I used it's identifier as a
> namespace name.

Yes, it does. That is: to use http://www.w3.org/ as a namespace name
is to claim that it refers to a namespace.

> David

-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/

Received on Wednesday, 7 June 2000 17:18:22 UTC