W3C home > Mailing lists > Public > xml-uri@w3.org > May 2000

Re: Namespace-by-retrieval is consistent and coherent

From: Michael Mealling <michael@bailey.dscga.com>
Date: Sun, 28 May 2000 12:34:44 -0400
To: "Simon St.Laurent" <simonstl@simonstl.com>
Cc: xml-uri@w3.org
Message-ID: <20000528123444.I11042@bailey.dscga.com>
On Sun, May 28, 2000 at 10:52:18AM -0400, Simon St.Laurent wrote:
> At 06:19 PM 5/27/00 -0700, Tim Bray wrote:
> >>     DEFINE NAMESPACE EQUIVALENCE AS A BYTE-FOR-BYTE COMPARISON
> >>     OF THE RESOURCE AS RESOLVED *AND* RETRIEVED.
> >
> >I think this proposal is coherent and consistent.  I also think that
> >given enough caching smarts, it is viable and implementable.  I'm not
> >sure that it has a very good cost-benefit trade-off, but reasonable people
> >may differ on this.
> 
> I think it's pretty clear from previous discussion that reasonable people
> would differ on this.  I don't think namespace values by deferencing is
> coherent for a number of simple reasons:
> 
> 1) Retrieval costs and failures.  Many XML Namespaces currently in use
> point to nowhere - deliberately.  Some URI schemes (notably mailto: and
> URNs) may not return a resource directly anyway.  Even if it's possible to
> retrieve, this adds substantial overhead to processing, and requires
> parsers to handle lots of protocols well.  (HTTP redirects are a simple but
> ugly case for many XML parsers.)

Point of information: URNs are not required to resolve to anything.
RFC 2141 et al specifically say that a URN can simply identify and
need not have a resolvable resource behind them in order to be useful.
Specifically, potential URN namespaces such as GUID or OID never
define a way of resolving them within their own specifications...

So, yes, you can have URIs who's job is just to identify and not actually
resolve to anything...


-MM

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Received on Sunday, 28 May 2000 12:46:00 UTC

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