W3C home > Mailing lists > Public > w3c-sgml-wg@w3.org > November 1996

Re: Simple solution? Pub. Idents. vs URN.

From: Paul Prescod <papresco@calum.csclub.uwaterloo.ca>
Date: Thu, 28 Nov 1996 06:35:33 -0500 (EST)
Message-Id: <199611281135.GAA22466@calum.csclub.uwaterloo.ca>
To: bosak@atlantic-83.Eng.Sun.COM (Jon Bosak)
Cc: w3c-sgml-wg@w3.org, bosak@atlantic-83.Eng.Sun.COM
> I personally believe that the parallel almost universally drawn
> between persistent identifiers and IP addresses is the single largest
> obstacle to understanding this entire problem.  In fact, document
> resolution and domain name resolution are almost exactly opposite
> problems.
> 
> Domain name resolution is when I'm given one of a possibly unlimited
> number of names for a machine and I need to find the one machine
> that it refers to.
>
> Document resolution is when I'm given the name of a document and I
> need to find one of its possibly unlimited number of copies.

Not so. The W3C Addressing/Activity page describes how it is already
possible for one domain name address to point to multiple IP addresses. So
domain name resolution is *also* sometimes a many to one, one to one, or 
one to many mapping. That this process is currently difficult, and underused
is a bug in DNS and DNS systems, not in the basic DNS problem space.

So I don't see  how these are opposites. In my message I should have said
that every document has *at least* one actual location, instead of "every
document has a location."

> To think of "the document" as a thing bound to a location in the same
> way that one thinks of "the machine" as a thing bound to a location
> is, in my opinion, to commit a category error that hopelessly muddles
> all further thought on the subject.  

The same is true of machines. If DNS does not allow me to set up a machine in
Tokyo and Johannesburg with the same name a one in California, to serve the
same information, then DNS (or DNS implementation) is incomplete.

>The notion that there is One True
> Copy of a text stopped being accurate with the invention of the
> printing press, and we stopped referencing documents that way even
> before then.  The biggest problem with URLs is that in attempting to
> implement hypertext they misrepresent the idea of text itself.

I don't understand that at all.  URLs point to *one of* the locations of a
document. That isn't a misrepresentation, it is just under-powered technology.
URNs will point to all of the locations of a document, but in the end, they
will resolve to URLs, just as domain names resolve to a particular IP 
address (Paul ducks) of potentially many that may be bound to a particular
domain name.

Am I still misunderstanding you?

 Paul Prescod
Received on Thursday, 28 November 1996 06:35:26 EST

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