W3C home > Mailing lists > Public > uri@w3.org > September 2001

Re: Excess URI schemes considered harmful

From: Sean B. Palmer <sean@mysterylights.com>
Date: Wed, 26 Sep 2001 16:35:44 +0100
Message-ID: <016e01c146a1$05c59b80$a8d993c3@y0r1d9>
To: "Roy T. Fielding" <fielding@eBuilt.com>, "Harald Alvestrand" <harald@alvestrand.no>, "Al Gilman" <asgilman@iamdigex.net>
Cc: "Eastlake III Donald-LDE008" <Donald.Eastlake@motorola.com>, "'Rob Lanphier'" <robla@real.com>, <uri@w3.org>, "Dan Connolly" <connolly@w3.org>, "Tim Berners-Lee" <timbl@w3.org>, "Larry Masinter" <LMM@acm.org>, "Dan Zigmond" <djz@corp.webtv.net>, "Rich Petke" <rpetke@wcom.net>
> AG:: Because the standard syntax is only safe (recognizable)
> the RFC-822 header context.  The point of URIs is that they
> creates a single non-colliding space for "references outside
> this context" which is not aware of what is a type, what is an
> instance, or much of anything else.

It depends really upon the context of use of the identifier, and how useful
it is to refer to (in this case) the content type as a first class object
with a single identifier, rather than creating some machinery to identify
it as an unambiguous term within the system.

For example, RDF doesn't particularly need a URI scheme to identify media
types, because it's much easier to just invent a predicate relationship
between some node and a literal value, which is to the effect that the
literal value is the unique MIME type for the subject.

   :mimeType a daml:UniqueProperty .
   <http://example.org/> :mimeType "text/html" .

The benefit there is that it's a 30 second hack using DAML, rather than a
consensus based registration process that may take months, and for the
payoff that you have to have systems that recognize DAML. In the RDF
context, that isn't much of a setback.

So I disagree that MIME content type labels are only safe in the context of
RFC 822 headers, but I do agree that on many occasions a URI scheme/URN
namespace for them would be more than helpful.


Kindest Regards,
Sean B. Palmer
@prefix : <http://webns.net/roughterms/> .
:Sean :hasHomepage <http://purl.org/net/sbp/> .
Received on Wednesday, 26 September 2001 11:41:30 UTC

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