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Re: Namespace squatting: please don't

From: Dan Connolly <connolly@w3.org>
Date: Fri, 15 Sep 2000 17:48:01 -0500
Message-ID: <39C2A721.11BCA543@w3.org>
To: Jonathan Borden <jborden@mediaone.net>
CC: www-rdf-interest@w3.org, melnik@db.stanford.edu
Jonathan Borden wrote:
> 
> Dan Connolly asserted:
> 
> >
> > I just noticed the following:
> >
> > [[[
> >  <!ENTITY rdf  'http://www.w3.org/1999/02/22-rdf-syntax-ns#'>
> >  <!ELEMENT section ANY>
> >  <!ATTLIST section rdf:instance CDATA "">
> > ]]]
> >
> > --
> > http://www-db.stanford.edu/~melnik/rdf/examples/text.xml.rdf
> > Fri, 17 Dec 1999 00:17:04 GMT
> >
> > That's inconsistent with the intended use of the namespace name
> > http://www.w3.org/1999/02/22-rdf-syntax-ns#
> >
> > So... like...
> >
> > Hey, You Kids, Get Off My Lawn!
> >
> > -- http://www.goddamn.com/content/lawn.cfm
> 
>     Since you include a URI, is this an RDF assertion?

Er... huh?

>     And since you bring up the topic:
> 
>     What specification constrains the contents of a namespace?

If you mean "what specification constraints the content
you get back when dereferencing a namepace name" then
the answer is the same as the answer to
"what spec constrains the content
you get back when you dereference an HTML href?"
There is no spec for what you get back in the general case.


> It is logical
> that the owner of a namespace (whatever that means) may restrict the ability
> of others to add elements to the namespace but where is this precisely
> specified?

That ends with a question mark but parses as a declarative
sentence. Help? Do you mean "is it logical ..."?

Absolutely, it's logical for the issuer of a namespace
name, like any other URI, to say what that URI means,
and what it doesn't mean.

W3C has stated both:

	The formal namespace name for the properties and
	classes defined in this specification is
	http://www.w3.org/1999/02/22-rdf-syntax-ns#. 

	-- Resource Description Framework (RDF) Model and Syntax Specification
	http://www.w3.org/TR/1999/REC-rdf-syntax-19990222/
	Wed, 24 Feb 1999 14:45:07 GMT
	aka http://www.w3.org/TR/REC-rdf-syntax

and

[[[
This is the RDF Schema for the RDF data model as described in
the Resource Description Framework (RDF) Model and
Syntax Specification http://www.w3.org/TR/REC-rdf-syntax
]]]

--  http://www.w3.org/1999/02/22-rdf-syntax-ns#
Wed, 24 Feb 1999 00:54:18 GMT

And W3C has promised, by way of the RDF schema spec,
never to change the content of
http://www.w3.org/1999/02/22-rdf-syntax-ns#

I don't suppose we have explicitly stated that
the inteded usage of http://www.w3.org/1999/02/22-rdf-syntax-ns#
will never change, but I think that is the case.

>     The URI in question dereferences an RDF Schema. Are you saying that RDF
> Schemas constrain namespaces?

Yes, I am saying that RDF schema can be used to state
the intended use of namespace names.

> If yes, then how can we assert that the Schema
> model is closed?

i.e how can we say, in a schema "and there are
no other properties in this namespace"?
Fair question.

But many of the thingies in the RDF namespace
aren't RDF properties/classes; things like
rdf:RDF, rdf:about, rdf:resource are strictly
syntactic gizmos. And I think it's clear
that the RDF 1.0 spec says how many of them there
are, and that there aren't any others; the syntax of the
language is specified by a grammar, and grammars
have that closed nature.

i.e. it says how to parse RDF 1.0 documents
and get a model, and for those purposes,
rdf:instance isn't special in any way;
it's just a property like rdf:type
or rdf:value.


>     Isn't a major point of RDF that Properties are first class objects, and
> that Properties can have multiple rdf:domains ... this whole long discussion
> about models ... so what's the deal? If you are using an RDF Schema to
> specify the RDF Namespace URI (a good thing IMHO BTW)

no, rdf:RDF and rdf:resource and rdf:about and the
other bits of syntactic magic aren't specified by
any RDF schema.

> then you are on shaky
> ground with your complaint (that is to say if the URI pointed to a DTD you
> would be on firm ground).
> 
>     Do you have the same issue with TimBL's rdf:for
> (http://www.w3.org/DesignIssues/Syntax)?

No, TimBL doesn't say that rdf:for is short for
http://www.w3.org/1999/02/22-rdf-syntax-ns#for .
At least I hope he doesn't mean it that way.

I have a different issue with that document: namely,
that he doesn't give a URI to bind to his
rdf: prefix. If he did, I could use that URI
in XSLT transformations, etc. to refer to his idea.

Contrast with

[[[
If the URI of this page is used as a namespace name then
it refers to the namespace which contains these classes
and properties (prefixed by "u" above).
]]]

-- Web Architecture: Generic Resources
http://www.w3.org/DesignIssues/Generic
Fri, 08 Sep 2000 21:17:54 GMT

-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Friday, 15 September 2000 18:50:20 GMT

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