Just require URLs

Paul Prescod paul at prescod.net
Wed Jun 2 00:27:33 BST 1999

Jonathan Borden wrote:
> Interestingly 2396 defines 'resource' as
> either an abstract or physical entity, an example of an abstract entity
> would be a namespace. 

Tim claims that a namespace is not a resource of any sort. The namespace
mechanism uses a string that happens to be a URI. The existence of the URI
implies the existence of the resource but it does not imply that the
namespace *is* the resource. I have pointed to terminology in the
namespaces specification that could be used to support that view but it
clearly was not the intent of at least one of the editors.

It is clearly the intent of RFC 2396 that it be possible to differentiate
between URLs and URNs based on syntax, not on context.

Furthermore, 2386 does not claim to update or obsolete 2141 which says:
"this document sets forward the canonical syntax for URNs" and says: "all
URNs have the following syntax..."

>     Under the definition of URN in 2396, a URN is any URI whose intention is
> to reference an abstract resource, act primarily as a name, and/or not be
> retrievable via a network. Under the definition in 2396, "urn" defines a
> scheme/namespace (URI namespace) whose intention is to serve *only* for
> URNs, however the spec suggests that any scheme e.g. "http" can serve to
> define a URN, given the definition of URN in 2396 (part of which my earlier
> message quotes).

It does not suggest any such thing. Rather it goes out of its way to
justify its use of URLs as examples instead of URNs. If they could be
interepted either way, why bother? URN "identifiers [are] drawn from a set
of defined namespaces." *Defined URN Namespaces* -- as in

>     So, my reading of RFC 2396 and the XML namespace spec leads me to
> conclude that all URIs used as XML namespaces are properly URNs regardless
> of the URI scheme prefix.

As David Megginson said much more eloquently, you can read as much into
the RFCs and IDs as you can into the Bible. I have never heard a reading
compatible with yours before so it certainly isn't a basis for
interoperable behavior. If http://www.w3.org can be interpreted as a URN
without some explicit statement in the containing context but based rather
on the state of someone's neurotransmitters and "intent" then we have are
destined to have a big interoperability problem.

 Paul Prescod  - ISOGEN Consulting Engineer speaking for only himself

"Silence," wrote Melville, "is the only Voice of God." The assertion,
like its subject, cuts both ways, negating and affirming, implying both
absence and presence, offering us a choice; it's a line that the Society
of American Atheists could put on its letterhead and the Society of
Friends could silently endorse while waiting to be moved by the spirit
to speak. - Listening for Silence by Mark Slouka, Apr. 1999, Harper's

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