Re: URI-protocol mapping (was Re: How to add new "protocols" ?)

touch@isi.edu
Fri, 21 Feb 1997 07:54:43 -0800


From: touch@isi.edu
Date: Fri, 21 Feb 1997 07:54:43 -0800
Message-Id: <199702211554.AA05345@ash.isi.edu>
To: rdaniel@acl.lanl.gov, connolly@w3.org
Subject: Re: URI-protocol mapping (was Re: How to add new "protocols" ?)
Cc: liberte@ncsa.uiuc.edu, touch@isi.edu, uri@bunyip.com

> OK, I'll bite: how is it that "location-dependent" vs.
> "location-independent" is a technical distinction?
> What mechanism depends on or uses the distinction in
> any way? What's the test for "location dependent"?
> 
> For 20 points: tell me the location of http://www.w3.org/.

1. the protocol is completely specified in this, i.e.,
	HTTP over TCP on the default port of 80

2. www.w3.org is a fully-qualified DNS name 
	The fact that DNS round-robining maps this to different
	addresses depending on when the query is posed is no
	different from the fact that all DNS names are symbolic,
	and that the mapping to IP addresses is done at resolution
	time.

> The evidence you give -- that you would have a hard time calling
> it a URN -- is exactly the sort of _non-technical_ difference
> in perspective that I'm talking about.

It's very technical. The host requirements RFC specifies locations
as either fully-qualified DNS names or IP addresses. And that's what
you have here. I.e., you have as much of a location as the internet
allows.

Joe
----------------------------------------------------------------------
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/