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

Re: Can everyone be happy?

From: Henrik Frystyk Nielsen <frystyk@microsoft.com>
Date: Thu, 22 Jun 2000 09:43:07 -0700
Message-ID: <00cd01bfdc68$f42a8500$83b11eac@redmond.corp.microsoft.com>
To: <keshlam@us.ibm.com>, "David Carlisle" <david@dcarlisle.demon.co.uk>
Cc: <abrahams@acm.org>, <xml-uri@w3.org>
> Having said all that: It still remains unclear that URIs do, in fact,
have
> the characteristics desired for use in identifying namespaces. The
behavior
> will not match most user expectations, and in fact the behavior must be
> constrained (stronger inequality) in a way that diverges somewhat from
the
> normal interpretation of URIs. I'm willing to accept those weaknesses if
> that's what it takes to put this debate behind us.

I depends on what URI space you use - it is the responsibility of the
generator of a document that the identifiers used are used in accordance
with the semantics of those names. If I choose to use MIME header fields
or DNS hostnames, I have to live with that they are case-insensitive.

This doesn't mean that the consumer of those names have to know these
rules but I as a generator of a document must know. Otherwise, there is no
way to enforce identification and we have the "case A" that James Clark
warned against.

> And I remain _extremely_ unconvinced that premitting relative references
to
> namespace names is desirable, even if this way of viewing the problem
makes
> the resulting breakage architecturally meaningful. The behavior will be
> excessively fragile, and the benefits seem excessively weak. Better to
> remove the land mines than to put up signs and maps.

It depends on where you think namespaces in practice are going to come
from:

* Only a few sites like http://www.w3.org will produce namespaces
* Everybody will produce their own namespaces

In the former case, relative URIs will be really rare, in the latter
really common. For example, generators of documents do not know the base
URI of where their documents are going to end up - they publish on ISP
sites and all kind of other places and without using relative URIs there
is no way they can do this. Relative URIs also allows "pre-publishing"
testing on non-production machines where they have to use relative URIs.

One thing that I am sure about is that if the latter case is going to be
the common case then people are going to use relative URIs regardless -
otherwise they can't do what they want to do.

Henrik
Received on Thursday, 22 June 2000 12:43:45 GMT

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