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Re: Significant W3C Confusion over Namespace Meaning and Policy

From: Patrick Stickler <patrick.stickler@nokia.com>
Date: Wed, 16 Feb 2005 11:46:22 +0200
Message-Id: <d43b6190f5b61773c444b4b966f900e3@nokia.com>
Cc: <www-tag@w3.org>, "ext Norman Walsh" <Norman.Walsh@sun.com>
To: "ext Dare Obasanjo" <dareo@microsoft.com>


On Feb 15, 2005, at 23:16, ext Dare Obasanjo wrote:

>> -----Original Message-----
>> From: www-tag-request@w3.org [mailto:www-tag-request@w3.org]
>> On Behalf Of Patrick Stickler
>> Sent: Tuesday, February 15, 2005 1:52 AM
>> To: ext Norman Walsh
>> Cc: www-tag@w3.org
>> Subject: Re: Significant W3C Confusion over Namespace Meaning
>> and Policy
>>
>>
>> Exactly. Applications need to operate in terms of
>> vocabularies, document models, ontologies, etc. not in terms
>> of namespaces.
>>
>> There is the XSLT 1.0 vocabulary.
>>
>> There is the XSLT 2.0 vocabulary.
>>
>> Those two distinct vocabularies happen to share common terms;
>> but do not employ the exact same set of terms.
>>
>> Those shared terms happen to be defined with the same namespace name.
>>
>> The namespace name does not identify either vocabulary.
>
> Then what does the namespace name identify?

It depends on which interpretation you mean. What the
URI used as a namespace name identifies *as a URI*
cannot be known insofar as its use as a namespace name.

What that URI identifies *as a namespace name* is, well,
a namespace; a space of names.

What's important is to not confuse those two interpretations
of the URI used as a namespace name.


> XML namespaces seem to grow
> more and more useless by each passing day.

Not at all. Rather, the utility of XML namespaces has
remained constant since their introduction -- but folks
who have mistakenly presumed certain meaning or function
of namespace names which is not licensed by the specs
are simply finding that their presumptions were wrong,
and thus, their solutions are not built on solid ground.

A good many hacks and tricks based on interpeting namespace
names in the web context, as URIs, are simply starting
to unravel.

Agents that presume that they can take the URI used as
a namespace name, dereference it, and obtain any information
relating to the namespace, or any terms grounded in that
namespace, or any schemas/models/etc. relating to those
terms, etc. are not going to function reliably for
arbitrary content encountered on the web; because such
presumptions are not licensed by the specifications and,
at best, simply reflect localised practices.

Well...  that's probably beneficial in the long run,
since it is making clear what essential functionality
is actually provided by namespace names, and which
erroneous presumptions will not scale over time;
ultimately leading to better applications and solutions
(hopefully).

>
>> Applications are free to use either vocabulary, and any
>> differences in the set of terms employed by either vocabulary
>> should be irrelevant to a particular application using a
>> particular vocabulary, since the application is concerned
>> with the vocabulary -- and not the syntactic details of how
>> the identifiers for terms are constructed.
>>
>> The confusion arises if/when folks presume that namespace =
>> vocabulary and/or namespace = document model and then
>> (understandably) worry about how applications are impacted
>> when new terms are minted using a particular namespace --
>> presuming (wrongly) that doing so introduces those new terms
>> into an existing vocabulary. If the existing version of the
>> vocabulary does not include those terms, and the application
>> is clear which version of a vocabulary some data is presumed
>> to conform to, then it should simply not care about namespaces at all.
>
> So how does one identify a vocabulary?

This is a very important question, and one that still requires
some work, experimentation, and thought (not necessarily in
that order ;-)

Best to pursue that discussion in another forum.

> Passing the buck by claiming that
> XML namespaces do not identify vocabularies doesn't change the fact 
> that
> the problem exists.

Clarifying a misunderstanding and identifying the real problem
is not "passing the buck".

Better to spend time working on real problems than non-problems
percieved to exist due to a misunderstanding.

> Going back to the root of this discussion
> application scenarios broke when the W3C introduced xml:base and the
> same will happen with the introduction of xml:id. What process will be
> put into place to prevent this from happening in the future in across
> the family of XML specifications produced by the W3C?
>

I'm afraid I don't entirely follow what you are referring to here.
Break how? I would suspect that if applications are breaking, then
they are making presumptions about the significance of the namespace
that are not strictly licensed by the specs.

Cheers,

Patrick
Received on Wednesday, 16 February 2005 09:52:35 GMT

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