W3C home > Mailing lists > Public > uri@w3.org > September 2001

Re: Excess URI schemes considered harmful

From: Sean B. Palmer <sean@mysterylights.com>
Date: Wed, 26 Sep 2001 16:59:27 +0100
Message-ID: <019c01c146a4$54055120$a8d993c3@y0r1d9>
To: "Graham Klyne" <GK@ninebynine.org>
Cc: <uri@w3.org>
> Because different URN nids don't require different handling
> by software that handles them (unlike different URI schemes,
> which MAY require different handling).

Hmm... I guess I agree with you there, although intuitively it doesn't feel
right. If I come across an arbitrary URI, and I am only told that it's a
URI, then I will handle it just the same as I would any URI, including
URNs. In other words, I don't particularly believe that the properties of
URNs are *inherently* different from that of any given URI. It just so
happens that due to the culture behind them, and the way in which they are
delegated, they all end up being registered as location independent
identifers. But they can still resolve, etc.

> [...] I believe a "very high shared knowledge of the properties
> of" URNs is already present, because they don't really have
> any significant properties other than being unique, persistent
> names.

Well, URIs are unique persistent names too. But it depends upon context...
for example:-

   http://example.org/

Assuming that some run-of-the-mill organization owned that domain name,
would the URI be persistent? Let's say example.org is a company selling
widgets, and they hand it over to a company making sprockets. Some people
may argue that the traditional usage of the identifier (the binding of the
identifier to a resource which is about widgets) has changed. However, what
if there is no context to the link, and I'm just demonstrating that there
is a domain called example.org? The URI is persistent in that context
because it always identifies the HTTP server on the domain example.org.
Even if there isn't an HTTP server there! [1]

So it always depends upon context, and I think that many of the problems in
arguing about persistence is that people disagree on what the context of
use of an identifier is. Some think that an HTTP URI identifies a document,
some think it identifies a concept, some think it identifies a location on
the internet...

The measure of any persistence of a URI is in the quality of service in
context over a period of time. Without the qualifying context, anyone can
argue convincingly that a URI is both persistent or non-persistent. Draw
whatever conclusions from that about URNs:URIs that you may :-)

[1] A lower level example rather than a higher level example would be if I
cited soemthing on the widget page, and then next week that material had
been removed, but the page was still about widgets. In that context, even
the W3C datespace area is not persistent!

--
Kindest Regards,
Sean B. Palmer
@prefix : <http://webns.net/roughterms/> .
:Sean :hasHomepage <http://purl.org/net/sbp/> .
Received on Wednesday, 26 September 2001 11:59:48 UTC

This archive was generated by hypermail 2.3.1 : Tuesday, 6 January 2015 21:25:03 UTC