Re: Is a namesapce a resource? - was: duck

Hmmm... you got me musing.


Ignoring, for now, issues of relative and context-dependent URIs.  If a 
namespace is a resource, and a namespace name is a URI:  what resource is 
identified by that URI?  Logically, it is the namespace (which may be an 
abstract, non-retrievable entity).  But if one chooses a namespace name 
that can also be used (directly) to retrieve some schema bound to the 
namespace, then the resource identified by the URI ipso facto is the schema 
document.  (Or is it?)

Where now the 1:1 correspondence between URIs and resources?


<sidebar>
There is, I think, a related issue:  I had thought that content negotiation 
might be used to select different representations of a schema associated 
with a URI (e.g. text document specification vs RDF schema).  But if the 
schema-URI chosen is one that directly indicates a specific document, then 
how is the abstract schema concept to be distinguished from a specific 
descriptive document?

I have always been uncomfortable with the practice that http: URLs be used 
as abstract resource names -- here I think I am seeing some concrete 
reasons for this unease.
</sidebar>


(I think a basic formal algebra of URIs and resources might help to set 
some of these issues in place.  I have some early thoughts about this.  Dan 
Conolly mentioned at WWW9 doing some formal web modelling work with Larch.)

#g
--

At 02:32 AM 6/8/00 +0800, Rick JELLIFFE wrote:
>
> > From: Tim Berners-Lee (timbl@w3.org)
>
> > Maybe it is that he concpet of self-describing documents just does not
> > exist for many people.  While I can understand that not everyone would
> > put there energy I had not anticipated that there would be an actual
> > resistance to identifying namespaces as resources.
>
>But isn't the reason people don't want to think of a namespace as a
>resource because people they see it as a slippery slope to
>proprietorizing XML: when Microsoft said that BizTalk namespace URIs
>locate a schema in a particular format, that means that in order to use
>a Biztalk document one has to buy into the schema language (i.e., the
>products) that it requires.
>
>About a year ago, I wrote an posting to XML-DEV that "Namespaces is
>dead" trying to alert people to the problem of equating namespace with
>schema 1:1. As long as W3C prevaricates with variations on "the
>namespace URI should/can locate something which can/should
>define/describe the language", the chances of getting a workable, open
>system decreases.
>
>We need definite ways to discover and retrieve multiple resources keyed
>from a namepace URI: we need to be able to find if particular resources
>relevant to that namespace in some domain are there or not there. Having
>a simple relationship between namespace URI and some rendition of some
>definitional entity at the other end is little use: the current
>lucky-dip system where you just don't know what kind of thing may or may
>not be at the other end is no basis for a workable system.
>
>The constituency who is opposed to a simple retrieval from a namespace
>URI not only include those who don't feel keen on self-describing
>documents, but more importantly (and, I think, more numerously) includes
>those whose requirements for "self-description" are not satisfied by the
>current vague hand-waving.
>
>This is a point that has been made many times (e.g. by Tim Bray) on this
>list so far: so I hope when Tim BL is talking about people for whom "the
>concept of self-describing documents just do not exist" he does not
>blanket everyone who is against the simplistic method he has been
>putting forward.
>
>To the contrary, I would say that the biggest thing holding back the
>development of a "semantic web" at the moment is the failure of
>architecture at the W3C: that failure being that people need conventions
>to allow multiple resources in different domains to be retrieved, keyed
>by the namespace.
>
>
>Rick Jelliffe

------------
Graham Klyne
(GK@ACM.ORG)

Received on Thursday, 8 June 2000 06:11:58 UTC