W3C home > Mailing lists > Public > xml-uri@w3.org > May 2000

RE: Namespaces and namespace names: a new synthesis?

From: Larry Masinter <masinter@attlabs.att.com>
Date: Fri, 26 May 2000 23:33:48 -0700
To: "John Cowan" <cowan@locke.ccil.org>, <xml-uri@w3.org>
Message-ID: <NDBBKEBDLFENBJCGFOIJIEFMCMAA.masinter@attlabs.att.com>

> 1) Namespaces are resources (they have identity and can be referenced
> by URIs).


> 2) Every namespace has a string property called its namespace name.

It's not clear that the quantifier "every namespace" is finite, but sure,
I think this is included in the namespec space.

> 3) A URI which identifies a namespace can be constructed by prepending
> "data:," to the namespace name.  (The namespace named "foo" has the URI
> "data:,foo".  The namespace named "http://www.w3.org/2000/xyz" has the
> URI "data:,http://www.w3.org/2000/xyz".)

Oh, no! That's nonsense. The only resource a data URI identifies is the
data contained in the data URI. Trying to say that a data URI can also
be used to identify a resource is just nonsense. If a namespace is a
then a URI must be used to identify it. I think it's a silly idea to
use 'http' URIs to identify resources, since they're already used to
the resource which is "what's served by this web server when you give it
this path in the HTTP request".

Maybe the problem we got into was because all of the W3C recommendations
use http URLs to identify resources that aren't really served by http

> 4) Namespace names MUST match the production "URIreference" in RFC 2396,
> except that the empty string is not a valid namespace name.
> 5) Namespace names SHOULD match the production "absoluteURI" in RFC 2396.

I think these are fine.

> 6) Two URIs identify the same namespace if they are string-equal
> (but the converse may or may not be true.  A fortiori, no two namespaces
> can have the same namespace name.)

You have to define what it means for two namespaces to be "the same".
There's no obvious, unique, equivalence relationship.

> 7) Namespaces are declared in XML documents using their namespace
> names (not their URIs).

This is the same thing you said before, I think. I'm not sure what it means
when you say 'not their URIs' -- not the URI of the XML document, or
not the URI of the namespace (which might not have a URI)

> 8) Clients of the Namespace Rec MAY interpret namespace names as
> URI references for whatever purposes they desire.

Funny use of the word "client" here.

> ###
> With this compromise:
> 	all existing namespace-legal documents are still namespace-legal;
> 	namespaces are resources that have URIs and so can be the subjects
> 	and objects of RDF statements, though they don't have the
> 	same URIs that they were (assumed to) have before;

oh, no

> 	namespace comparison is based on string-equality between
> 	namespace declarations.
> I think this may produce at least an equality of dissatisfaction.
> Is there anyone who absolutely can't live with this scheme?

I can't live with using "data" URLs for a purpose so different than the
one they were intended for; there are lots of problems with it.

Received on Saturday, 27 May 2000 02:34:14 UTC

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