RE: The case against URNs

> -----Original Message-----
> From: Paul Prescod [mailto:paul@prescod.net]
> Sent: Sunday, October 06, 2002 6:30 PM
> To: Champion, Mike; www-tag@w3.org
> Subject: The case against URNs
> 

 
> So I stumble upon one of these URIs and I would like to know:
> 
>   * what type of thing is this?
>   * what is its current state?

I don't claim to have thought this all through, just wondering what the
arguments against URN-like URIs are.  Thanks for a the explanation.

Still, I guess my approach would be to say that there can be all sorts of
knowledge bases that refer to now://www.example.com/MyCar and they could
describe what type of thing it is, its current state, etc.  Or, for any
non-trivial abstract resource, they could describe various assertions, from
various people with various degrees of authority, about what it is or what
state it it's in.  (Think of now://www.whitehouse.gov/ ... the owner of that
site's assertion about the state of the thing it refers to is far, far less
interesting than other people's assertions about the resource.  That's why
the Google pays no attention to META tags, no?).

If the owner of a site does want to put metadata describing the state of the
abstraction it represents, it can always put it at
http://www.whitehouse.gov/index.htm (or index.rdf or index.rddl ...).  The
now:// scheme at least makes explicit that there's a difference between
www.whitehouse.gov the website and www.whitehouse.gov the Presidency (or the
residence at 1600 Pennsylvania avenue, or whatever).  

> they COULD 
> answer the question by putting up a little snippet of HTML and RDF 
> accessible through the URI, they SHOULD NOT because it would be 
> confusing to people.

I guess I don't understand this ... people are confused all the time and
Just Deal With It ... machines that are confused either do arbitrary things,
exploiting the fact that one contradiction in a logical system allows
anything at all to be "proved"  ... or (hopefully) start waving robot arms
around and babbling "that does not compute". [dates me back to the '60s,
eh!]

My assertion -- which I don't hold all that strongly, but would have to be
persuaded to drop -- is that the "name" http://www.whitehouse.gov is
fundamentally ambiguous -- it may be the site, or some abstraction -- and
hence automated inferencing systems will always get confused easily when
confronted with it.  Of course, some *convention* should be devised like
http://www.whitehouse.gov/President#Current but then we get into well-argued
territory (is that a label "Current" in a representation of the resource
retrieved by dereferencing http://www.whitehouse.gov/President or the
abstraction "Current President of the United States"? )  I suppose that
could be resolved by fiat ... but how are you going to get people to follow
it?  It seems better to start with something URI scheme that has not been
registered (now:// ???) so that any application that has no idea what
now://www.whitehouse.gov is all about will not attempt to do anything with
it, and applications that do understand the now:// scheme can treat it as an
abstract name for something that it might reason about, look up in a
meta-database, etc. 

For that matter, I don't think I would care if some small set of methods
*did* apply to now:// URIs, so long as those were appropriately specific to
the abstractess of the URI, i.e. GETing now://www.whitehouse.gov was defined
as retrieving the owner of the namespace's assertions about itself or
something like that.  But since the results of a GET on
http://www.whitehouse.gov are already understood by hundreds of millions of
pieces of software and millions of web developers, it seems too late to say
that it SHOULD be a way of describing the type, state, etc. of that abstract
resource. 

Anyway, I hesitate to get into this ... as you say, it's well-trodden
ground, Dr. Fielding has probably devoted thousands of times more thought to
it than I have.  I just observe that for whatever reason -- possibly the
profound denseness of the non-enlightened -- this "axiom" does not seem to
be fitting cleanly into a realistic description of the Web as it actually
exists, or (as near as I can tell from following the debate from a distance)
TimBL's vision of the Semantic Web either.  Not having an intellectual or
emotional stake in the argument, this leads me to suggest "drop the axiom"
(not sure exactly which!) and see if the rest of the system falls into place
more cleanly.

Received on Sunday, 6 October 2002 19:41:14 UTC