W3C home > Mailing lists > Public > uri@w3.org > September 2003

RE: URNs for 'naming authority assignment', not 'permanent'

From: Daniel R. Tobias <dan@tobias.name>
Date: Wed, 17 Sep 2003 11:13:22 -0400
Message-Id: <4.2.0.58.J.20030917111317.06b2e270@localhost>
To: uri@w3.org




On 17 Sep 2003 at 12:30, Patrick.Stickler@nokia.com wrote:

 > The HTTP protocol seems only to be telling you how to obtain
 > representations of whatever is denoted by the URI, not how to
 > obtain the actual semantics/denotation of the URI.

Well, it's a URL (Uniform Resource Locator) rather than a URN
(Uniform Resource Name), after all.  Its intent has always been to
tell you how to obtain something rather than to define exactly what
it is.  Webmasters find this out to their dismay when links in their
site to relevant resources suddenly turn into links to porn sites
because a domain name expired and was picked up by an adult site
operator (this has happened with links in my site several times).
I'd say that, by definition, the URI http://foo.example/some/junk/
denotes whatever can be retrieved by the HTTP protocol using this
host and path.  It might lead to a Web page, a raw directory listing,
a redirect to another URI, a 404 Not Found error, or a domain lookup
error, and it may change to something else tomorrow, but the URI
refers to the abstract contents of the particular address.
Similarly, a postal address like "3 Maple Street" refers to a postal
delivery location, and perhaps to whatever building happens to be
there now, but doesn't tell you anything about who is actually at
that address, which is subject to constant change.  The building
there might even get torn down and replaced with something else, so
maybe there was a residence at 3 Maple Street 10 years ago but an
office building today.  The city might also decide to rename or
renumber their streets and addresses so that next year "3 Maple
Street" refers to a location across town from where it did this year.

These sorts of addresses can be used to designate where some resource
can be found at present, but have no definitional quality to
permanently and unambiguously define what the resource is.

Some other scheme, otherwise defined, is needed if you need such a
designation for permanent reference to an entity.

This is not to say that the manager of a particular group of URIs,
within a scheme that is a locator rather than a permanent name, can't
announce particular semantics for addresses, like to say that
http://foo.example/newsletter/latest.html will always have the latest
issue of their newsletter, while http://foo.example/newsletter/2003-
09-11.html has the September 11, 2003 issue, but that's not part of
the definition of the scheme and is not guaranteed to work
permanently; the manager could change his/her mind about the naming
structure, or be replaced by a new manager who rearranges everything,
or the site owner could go out of business altogether.

--
== Dan ==
Dan's Mail Format Site: http://mailformat.dan.info/
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Received on Wednesday, 17 September 2003 12:11:13 UTC

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