Symbolic vs Numeric identifiers (was Re: URL internationalization!)

Daniel LaLiberte (liberte@ncsa.uiuc.edu)
Mon, 24 Feb 1997 10:29:01 -0600 (CST)


From: Daniel LaLiberte <liberte@ncsa.uiuc.edu>
Date: Mon, 24 Feb 1997 10:29:01 -0600 (CST)
Message-Id: <199702241629.KAA04178@void.ncsa.uiuc.edu>
To: "Gregory J. Woodhouse" <gjw@wnetc.com>
Cc: uri@bunyip.com
Subject: Symbolic vs Numeric identifiers (was Re: URL internationalization!)
In-Reply-To: <Pine.SGI.3.95.970222104420.6939B-100000@shellx.best.com>
 <Pine.SGI.3.95.970222104420.6939B-100000@shellx.best.com>

 > > @ 09:17 21-02-97 -0800, Gregory J. Woodhouse a icrit :
 > > >i-nodes       filenames
 > > >IP addresses  domain names
 > > >URLs          ?????

 > On Sat, 22 Feb 1997, Francois Yergeau wrote:
 > > URLs are in the wrong place.  Applications do not deal with i-nodes, they
 > > deal with filenames.  

Gregory J. Woodhouse writes:
 > I'm not so sure they are. True, existing applications use URLs like
 > filenames, but then again, that's all we have. If there were no DNS, we
 > would use IP addresses [...]

Another way to describe this division is symbolic versus numeric
identifiers.  URLs are already symbolic, and as such, they belong in
the column with filenames and domain names.

Curiously, some people want URNs to be numeric to avoid all possible
semantic interpretations by humans.  Note that an i-node is the *real*
reference to a piece of data that may have many different file names,
and an IP address is the *real* identifier of a machine that may have
many different domain names.  Now a URN is the *real* identifier of a
resource that may have many different URLs.  But then shouldn't URLs
be mapped to URNs instead of the other way around?

People who want numeric URNs also envision a higher layer of human
friendly identifiers that would be mapped to the lower level numeric
URNs.  Where do URLs fit in this scheme then?  There are lower layers
of identifiers under i-nodes and IP addresses.

I should point out that it is not necessarily the case that "symbolic"
is to "numeric" as "name" is to "location", but people like to use
them that way.  At this point (in this message), I'm not saying which
way things should be - I would like to see this all brought out into
the open for discussion since there are some assumptions people are
making about how things should be done.

--
Daniel LaLiberte (liberte@ncsa.uiuc.edu)
National Center for Supercomputing Applications
http://union.ncsa.uiuc.edu/~liberte/