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Re: URI: Name or Network Location?

From: Patrick Stickler <patrick.stickler@nokia.com>
Date: Wed, 28 Jan 2004 10:09:17 +0200
Message-Id: <44F093E6-5169-11D8-ACA1-000A95EAFCEA@nokia.com>
Cc: "Hammond, Tony (ELSLON)" <T.Hammond@elsevier.com>, www-rdf-interest@w3.org
To: "ext Phil Dawes" <pdawes@users.sourceforge.net>

On Jan 27, 2004, at 05:46, ext Phil Dawes wrote:

> Hi Tony,
> Nobody else has answered this, so I'll have a stab.
> Hammond, Tony (ELSLON) writes:
>>> I simply can't fathom any real benefit to having a URI
>>> which, by definition, cannot be used to access such knowledge.
>> The reason is to keep the barrier to entry as low as possible. By 
>> explicitly
>> excluding dereference we have devised a very simple, focussed 
>> registration
>> mechanism which requires almost zero maintenance and is consistent 
>> across
>> the whole INFO namespace with a predictable behaviour (i.e. 
>> disclosure of
>> identity). This is a baseline service - think of it as something like 
>> the
>> Model T.
>> I agree that it would be useful to have resource representations 
>> sitting out
>> there on some network endpoint - but that is just way too expensive 
>> for the
>> namespaces we are interested in fostering. There are no (human) 
>> resources
>> available to maintain such an undertaking. The conclusion is that we 
>> either
>> go this zero-resolution route or we accept that many of these 
>> namespaces
>> will continue not to be represented on the Web. Which means that we 
>> will
>> continue to be frustrated by not being able to 'talk' about well-known
>> public information assets in Web description technologies.
> At work we've been using tag uris for the last 6 months in our
> internal RDF knowledge base (which is still reasonably small: ~50000
> triples), for much the same reason as the info URI scheme was created
> - that we wanted to represent abstract concepts and physical things
> without the dereference baggage and confusion.
> However, I've recently been convinced by Patrick's and Sandro's
> arguments for using http uris to denote abstract concepts. It gives us
> more flexibility in the future, for practically no cost.
> (The fact that Sandro was one of the inventors of the tag uri scheme
> give his arguments additional weight.)
> We are in the process of transitioning thus:
> I've registered a subdomain (call it sw.foo.com for illustrative
> purposes), and put a static html page up there which explains that
> this URI space is for abstract URIs used on the semantic web.
> Job Done.
> Now anybody who attempts to resolve a URI
> (e.g. http://sw.foo.com/marketmaker/2004/01/trades#mytrade35) gets a
> web page explaining that this uri represents an abstract concept or
> physical object on the semantic web.
> This sorts out the initial confusion that relates to using http URIs
> for abstract things, since anybody who is confused is most likely to
> try to resolve the http URI in an HTML web browser.
> So the cost is one webpage (plus a bit of webserver config), and a DNS
> subdomain entry.


> Does this make sense


> or am I missing something?


This is exactly how I personally think it should be done.

Though I'd go one step further (eventually, even if not at first) and
make that server URIQA enlightened, so that, for those resources which
have RDF descriptions, if folks dereference the URI, they get a metadata
description of the resource, rather than just a boilerplate response.

E.g., when you do an HTTP GET on http://sw.nokia.com/VOC-1/Vocabulary
there is no "typical" representation available for that resource, so
the URIQA enlightened server falls back to trying to provide a
description of that resource. If there weren't any description either,
it would return a 404 response (or could return a friendly boilerplate
response such as you describe above) but in this case, there is a 
so it returns the description as the representation (which it is).

If there *were* some other representation provided for typical GET
requests, you could still obtain that description either using MGET
or via a direct request to the http://sw.nokia.com/uriqa? portal.

But as a first step (or even only step) the approach you've adopted
is IMO the way to go, and leaves the door open to adding functionality
in the future.




Patrick Stickler
Nokia, Finland
Received on Wednesday, 28 January 2004 06:38:59 UTC

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