xml-dev - Content negotation in namespace URI resolution was RE: Treaty of Wulai

[Jonathan Borden <jborden@mediaone.net>]

Uche Ogbuji wrote:
> [from namespace REC]
> "URI references which identify namespaces are considered identical when
> they are exactly the same character-for-character.
> Note that URI references which are not identical in this sense may in fact
> be functionally equivalent. Examples include URI references which
> differ only in case, or which are in external entities which have
> different effective base URIs."
>
> And that's all I see there.  Am I missing something?  I don't see the
> rider WRT relative URIs.  I don't even see that the latter quoted
> sentence has been modified to reflect this prohibition.
>
> But anyway, this shows that there is no contradiction in the spec itself.
> The contradiction seems to be in the interpretations of the spec given by
> its editor and other very respectable parties in discussions by the spec.

From my previous post:

"Usage of relativeURIs as namespace names
while conformant to the namespace rec, results in such document having no
defined Infoset (i.e. it is not Infoset conformant)."

The namespace REC hasn't been changed. See the current Infoset draft for
language describing the deprecation of relativeURIs as namespace names.

>
> What I would like to be hashed out is a structure for defining
> the semantics
> one attaches to namespaces.

	e.g. RDF Schema?
>
> At its most basic, this could just be a distinction similar to that of
> well-formed/valid in XML 1.0.  Processors could be placed at two
> distinct layers: one that only treats namespaces as syntax and one that
> allows using the information represented by the URI itself for processing.

	yep. the user agent gets to choose how a namespace URI is interpreted
*beyond* as a namespace name.

>
> Within the latter layer, hopefully there would be some mechanism (even if
> just prose guidelines) for clearly expressing what semantics are intended
> by the XML application itself (I mean "application" in the strict sense,
> what is often called "vocabulary").  This way one processor could operate
> on both RDF and SOAP and be able to handle the very distinct ways in
> which they apply semantics to namespaces.

	Content negotiation has been suggested. Personally I think it is a good
idea because the responsibility for how semantics are applied lies with the
user agent.

	For example:

User agent desires to see a human readable description of namespace
vocabulary:

	Accept: text/html, text/plain, application/pdf

User agent desires to view a diagram of the directed graph describing the
ontology

	Accept: text/xml+svg, image/gif

User agent desires an XML Schema:

	Accept: text/xml+xsd ... or whatever the official content type of XSD
becomes

User agent desires an RDF Schema

	Accept: text/xml+rdf-schema

Jonathan Borden
The Open Healthcare Group
http://www.openhealth.org