What is a namespace ... really?

Terry Allen tallen at sonic.net
Sun Jan 17 02:35:48 GMT 1999

Tim Bray wrote, in two messages:
| At 01:24 PM 1/15/99 -0500, Roger L. Costello wrote:
| > It seems that people have
| >differing ideas on what it is. I would like to try to summarize the points
| >of view, and add my own two cents.
| >
| >(1) A namespace is just a URI.  It references some domain.  It is simply
| >there to tell an application/processor what domain the associated XML
| >elements hail from.
| This is the "view" that is expressed by the actual namespace spec.  Other
| views are simply incorrect.  There is not one word in the namespace spec
| that suggests that namespace URIs represent DTDs, and in fact specific
| language (look it up) that says that it's a non-goal that the URI
| actually points at anything.
| At 02:42 PM 1/16/99 -0500, Borden, Jonathan wrote:
| >The
| >question is whether a namespace has meaning outside of the name, or what
| >meaning does the namespace uri have?
| No meaning.  It's just a name.
| >
| >	some people suggest it is just a unique name. others suggest it 
| >ought to
| >point to a DTD, and others a schema. this issue is still under debate
| There are lots of interesting potential uses of the namespace URI.  None
| of them are either blessed or forbidden by the namespace spec.  For now,
| it's a name and that's all it is.

Now, RFC 2396 says (from the Abstract):

   A Uniform Resource Identifier (URI) is a compact string of characters
   for identifying an abstract or physical resource.  This document

and (from section 1.1):

         A resource can be anything that has identity.  Familiar
         examples include an electronic document, an image, a service
         (e.g., "today's weather report for Los Angeles"), and a
         collection of other resources.  Not all resources are network
         "retrievable"; e.g., human beings, corporations, and bound
         books in a library can also be considered resources.

So the "namespace" URI must identify a resource, which is anything
[any "thing"] that has identity.  (Obviously and tautologically,
the identity of any thing is itself; the thing makes its own identity
simply by existing.)  You say that it doesn't have to point to anything 
[any "thing"], and that it's "just a name".  So is the resource 
["thing"] identified by a "namespace" URI itself?  or is it the name 
of itself (maybe Kant could explain)?  How does something that is only 
itself or the name of itself encompass anything else?

Me, myself, I think this is a bogus use of URIs.  What you are
really using is DNS, and you don't need to use fake URIs to do so;
cf. the IOTP spec.  

Terry Allen				Veo Systems, Inc.
Business Language Designer              2440 W. El Camino Real
tallen[at]sonic.net                     Mountain View, Calif., 94040
Common Business Library - available at  http://www.veosystems.com/

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