W3C home > Mailing lists > Public > uri@w3.org > February 1997

Re: URI-protocol mapping

From: <touch@isi.edu>
Date: Tue, 25 Feb 1997 10:48:09 -0800
Message-Id: <199702251848.AA13026@ash.isi.edu>
To: touch@isi.edu, liberte@ncsa.uiuc.edu
Cc: uri@bunyip.com
> From liberte@sdgmail.ncsa.uiuc.edu Fri Feb 21 08:16:57 1997
> touch@isi.edu writes:
>  > At some point you must know
>  > 	who you're talking with
>  > 	what protocol to use
> If you are resolving a URN, you need to do the same thing, as you also
> pointed out (i.e. you need a protocol to find out what the protocol is).
> And when resolving a URL, you might be given that same information as
> a redirection.  Perhaps what you meant to say is:
>   At some point, you must know when you have the thing you requested
>   rather than an indirection to something else.

Nope - I was thinking the other way around. That to get to the 
first item you have to have a protocol and a fixed name. More
of a bootstrapping issue, with the observation that the overhead
of changing protocols is of little benefit thereafter.
>  > A URL is a context-independent absolute identifier.
> Consider all the ways I listed for how URLs can, in fact, be resolved
> that make them context dependent and relative.  What is wrong with any
> of them?

Precisely that there are many different ways. There should be exactly one.

> Here are several ways in which a URN can resolve directly to the object.
> The first looks almost like what people imagine, but there is an
> important distinction from the perspective of the client.  The client
> hands off a URN to be resolved by a proxy.  The proxy gets a URL back
> and resolves the URL and returns the result to the client.  Note that
> the client never saw the URL.

That level, and several others, is equivalent to application layer translation.
There is nothing I can do to prevent that; if it's invisible, I need
never know it, and I should not consider it part of *my* protocol, in
that case.

> Now let's get rid of the URL altogether.  The client sends a URN to a
> URN resolver.  The URN resolver maps the URN to some
> Now let's get rid of the necessary indirection in the URN resolver.

Where do you send the request now?
With what protocol?

THis is the basis of my objection.

Joe Touch - touch@isi.edu		    http://www.isi.edu/~touch/
ISI / Project Leader, ATOMIC-2, LSAM       http://www.isi.edu/atomic2/
USC / Research Assistant Prof.                http://www.isi.edu/lsam/
Received on Tuesday, 25 February 1997 13:48:19 UTC

This archive was generated by hypermail 2.4.0 : Sunday, 10 October 2021 22:17:34 UTC