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Re: What is at the end of the namespace?

From: Mark Nottingham <mnot@akamai.com>
Date: Fri, 16 Nov 2001 08:19:03 -0800
To: Patrick.Stickler@nokia.com
Cc: www-talk@w3.org, uri@w3.org
Message-ID: <20011116081850.E5078@akamai.com>

[ distribution trimmed as an act of mercy ]

On Fri, Nov 16, 2001 at 04:30:42PM +0200, Patrick.Stickler@nokia.com wrote:
> > >
> > SOAP Web Service endpoints can be named with http:* URIs, and
> > communicated with via XML representations shipped over HTTP. But
> > you can't download the service itself; that wouldn't make sense.
> 
> I would argue that the HTTP URI in that case does not denote the
> service, but a description of the service, if dereferencing the URI
> provides the SOAP instance.

I'm not following. SOAP probably isn't the best example, as it has
some odd properties, but its use of URIs to identify endpoints
clearly identifies services; service descriptions (e.g., IDLs like
WSDL) have separate identifiers. Both SOAP endpoints and URIs that
point at service descriptions will, when dereferenced, return a
representation of the resource in a format that the client is
presumed to be able to understand.


> Of course, there's a gray zone there. Does a CGI HTTP URI denote
> the service provided by the CGI application or the application
> itself, or just one access portal to that application (or service).
> Still, its a web-resource, and so it is reasonable to denote it
> with an HTTP URI.

Option two. The "CGI application" (which I'm interpreting as "a
bundle of code") might encompass one resource or many resources;
interactions with those resources might affect application state,
having follow-on effects to other resources exposed to the
application.

you may find
  http://search.ietf.org/internet-drafts/draft-baker-http-resource-state-model-01.txt
to be of interest.


> To use an HTTP URI to denote an abstract concept, such as "LOVE" or
> an ontological term, or a non-web resource such such as "The city
> of Paris" is quite odd. I fully agree.

But what is 'non-web'? The best definition of the Web is 'an
information space', which begs the question; how can you exclude a
concept from a global information space? HTTP does not define the
shape of the Web, or vice versa.

Whenever you use an HTTP URI in a Web browser, you use it for two
things; identifying the resource uniquely in a global namespace, and
dereferencing it to get a representation. 

Why is it so odd that some people only want to use it as an
identifier, without going off and dereferencing it? If it weren't
allowed to use a HTTP URI without dereferencing it, how would you
talk about the services available at those URIs without dereferencing
them? The HTTP itself uses URIs in this fashion (e.g. as index keys
in caches).


-- 
Mark Nottingham, Research Scientist
Akamai Technologies (San Mateo, CA USA)
Received on Friday, 16 November 2001 11:19:07 GMT

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