# Re: URNs and Meta-Information

Peter Deutsch (peterd@bunyip.com)
Sun, 17 Oct 1993 00:30:55 -0400

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    Message-Id: <9310170430.AA15346@expresso.bunyip.com>

    From: Peter Deutsch <peterd@bunyip.com>

    Date: Sun, 17 Oct 1993 00:30:55 -0400

    In-Reply-To: "Rob Raisch, The Internet Company"'s message as of Oct 16, 14:03

    To: "Rob Raisch, The Internet Company" <raisch@internet.com>, uri@bunyip.com

    Subject: Re: URNs and Meta-Information

[ Rob wrote: ]

[* speaking of URNs *]
. . .
> I would suggest we take the following steps.
>
> 1. Define what the URN looks like *WITHOUT* considering any other
> function than it be considered a unique and authoritative reference
> to a publisher's product. It is a name or an identifier which is
> assigned by the agency which maintains authority over it and it
> names or identifies what the agency determines.

Personally, I think the current format of
"prefix:authority:publisher:id" fits the bill nicely
(modulo the final debate on syntax). I also think that it
is perfectly feasible to build a dereferencing system
based upon this and known technologies such as DNS (see
below).

. . .
> I'd like to suggest that, without encoding the location of the authority
> which maintains pointers to the meta-information, we must rely on a central
> "authority of first resort." I don't think that this is a very good idea.

This is the approach taken by DNS and it seems to work
fine. In fact, I suspect that DNS can help us out on this.
In fact, right now I think I'd like to see us assign naming
authorities in a brand new domain just for this
(counter-arguments most welcome).

> In the previous example, if we encode the location of the ISBN number
> authority in the URN,
>
> urn:urn.isbn.org:0000-0000000000 rather than
>
> urn:isbn:0000-000000000
>
> we know where to go to find out who maintains the meta-information. The
> urn server at isbn would be queried with the opaque identifier, and would
> return the proper service to contact to retrieve the necessary meta-info.

Hmmm, encoding the full FQDN name here does makes the
string longer. Also, perhaps we don't want to hang such
servers under the .org domain. I suspect we'd be better off
with a ".urn" domain, with each new authority registered
getting its own subdomain. Thus:

isbn.urn
iso.urn

and so on.

We could even have further subdivision, by geography, by
organization, etc, as appropriate.

. . .
> This looks like four seperate transactions to retrieve data from a URN. No?
>
> At the very least, we need three seperate transactions: isbn-authority,
> meta-authority, and repository. But, this assumes that the location of the
> isbn authority is included in the URN.

Resolving a DNS query could easily take this many queries
(although to be fair they tend to be cheap searches).

> Either that, or we must encode the location of the authority for each
> namespace into each client. This also seems like a very bad idea for
> obvious reasons.
>
> Or am I way off track here?

I don't think so, although I'd tend to leave more of the
resolving work to the network and encode less into the URN
itself. Glad to see people considering the mechanics of
this, though...

- peterd

    --

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- Maybe in reply to: Rob Raisch, The Internet Company: "URNs and Meta-Information"
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