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Just to be clear. So in your world view a URI is an HTTP URL used as an identifier and not just a location?
-----Original Message-----
From: Paul Prescod [mailto:paul@prescod.net]
Sent: Mon 8/12/2002 9:23 AM
To: Simon St.Laurent; xml-dev@lists.xml.org
Cc:
Subject: Re: [xml-dev] quarantining namespaces
"Simon St.Laurent" wrote:
>
> Paul Prescod wrote:
> > When you ask Google for a cached page, it is not looking up the page
> > (that's the whole point). It is using the URI as an identifier and
> > checking what information it has associated with that identifier.
>
> But that re-use is tightly bound to the original locating power of
> retrieving documents using HTTP URLs.
We're in agreement!
First you said in another message that a Web with too many URI schemes
is not really integrated. That's true. That's why I am in favor of
standardizing on HTTP URIs and the HTTP protocol. (let's leave aside for
a second the issue of thing that are not primarily intended to be looked
up, like URIs)
Now you say that *identification* is much more powerful when it is
linked with *location*. I agree again. Insofar as there are no widely
deployed ways to do this indirectly, I think that the fact that HTTP
URIs do so *directly* is a very important strength.
> ... Using Google to look up
> information on URNs isn't nearly as useful unless someone's built a
> URL-based description.
I agree. That's why I strongly discourage the use of URNs!
> In short, while using URLs as identifiers may be a good tactic in some
> situations, taking that use as grounds to claim that the Web is built on
> URIs rather than URLs is a grotesque overreach.
I think that our problem is terminology. Some people say that URIs are a
set containing the union of the set of locators (URLs) and identifiers
(URNs). Let's call this the classical view: "Some things are waves and
some are particles."
"During the early years of discussion of web identifiers (early to mid
90s), people assumed that an identifer type would be cast into one of
two (or possibly more) classes. An identifier might specify the location
of a resource (a URL) or its name (a URN) independent of location. Thus
a URI was either a URL or a URN."
I say that *each* HTTP URI is *both* a locator *and* an identifier.
Mozilla uses it as a locator when you click the link. Google uses it as
an identifier when it looks up a cached page by URI. This is the
"contemporary" or "duality view". This view seems more powerful.
"Further according to the contemporary view, the term "URL" does not
refer to a formal partition of URI space; rather, URL is a useful but
informal concept: a URL is a type of URI that identifies a resource via
a representation of its primary access mechanism (e.g., its network
"location"), rather than by some other attributes it may have. Thus as
we noted, "http:" is a URI scheme. An http URI is a URL"
I agree with you that there were problems with the classical view in
general and URNs in particular. The only places I see URNs emanating
from are the IETF and Microsoft, an unholy union if I've ever heard of
one. ;) A URN is half of a URI.
--
"When I walk on the floor for the final execution, I'll wear a denim
suit. I'll walk in there like Willie Nelson, John Wayne, Will Smith
-- Men in Black -- James Brown. Maybe do a Michael Jackson moonwalk."
Congressman James Traficant.
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