Public Identifiers

W. Eliot Kimber eliot at
Sat Sep 19 23:44:45 BST 1998

At 08:59 AM 9/19/98 -0400, david at wrote:
>Henry S. Thompson writes:
> > "W. Eliot Kimber" <eliot at> writes:
> > 
> > > [names without a public resolution mechanism can never be really
> > > universal]
> > 
> > So has the W3C, as the obvious entity with a budget and an interest in 
> > a solution to this problem, ever showed its hand wrt this issue?
>Internet hostnames have a distributed and efficient public resolution
>mechanism, so they easily meet Eliot's criterion (as do URLs, more
>generally but with a few limitations); the problem with hostnames is
>not that they are not universal, but that they are not persistent: a
>hostname may have only one owner and resolve to only one IP address at
>any given moment, but next week the owner and IP address can be

But doesn't "persistent" mean "when I request a thing, I get one"?
Persistence is defined by the resource owner--if I transfer ownership of to someone else and they serve it from a different machine with
a different IP address, it's still if we say it is, and if we
do, then the resource is persistent. If we say "no, it's a new
and different, then the resource isn't persistent.  But
changing the IP address and ownership of the resource doesn't necessarily
affect the persistence.

Of course, there can always be a mismatch between the expectations and
desires of resource users with regards to persistence and the expectations
and desires of resource owners. The owner of the LA Dodgers baseball team
probably considers the Dodgers to have exhibited persistence as a team
since it started life as the Brooklyn Dodgers--fans from Brooklyn may not

Persistence in a network environment can really only mean "it's more likely
to be there than not" or "I get what I expect to get". Nothing is truly
persistent.  I don't see much profit in getting too existential about the
term "persistence".  I think the real issue is about management of
persistence: how easy is it for resource owners to manage names so that the
use of a given name gives the appropriate result for the appropriate length
of time and how easy is it for resource users to invoke those names.


<Address HyTime=bibloc>
W. Eliot Kimber, Senior Consulting SGML Engineer
ISOGEN International Corp.
2200 N. Lamar St., Suite 230, Dallas, TX 75202.  214.953.0004

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