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

Re: Why are relative NS identifiers used?

From: John Aldridge <john.aldridge@informatix.co.uk>
Date: Thu, 18 May 2000 12:01:04 +0100
Message-Id: <>
To: xml-uri@w3.org
At 13:31 16/05/00 -0400, Rick JELLIFFE wrote:
>Nor will it work to keep on avoiding this issue: if Tim BL thinks the 
>architecture of the WWW should involve directly dereferencing namespace 
>identifiers to get schemas...

>The Schema WG has not gone down this route. The reasons are
>  1) performance
>  2) it is not the XML Schemas job to say what a NS URI resolves to.

Bravo.  This more or less sums up my concerns.  To add a few notes...

>  1) performance

And reliability (my ISP is not 365/24 -- how about yours?).
And accessibility to offline users.

I suppose that both of these could be addressed by a caching system -- 
including the ability to populate this cache ahead of time on systems which 
are not and never have been connected to the internet -- but that does not 
seem to be a widely deployed technology.

>  2) it is not the XML Schemas job to say what a NS URI resolves to.

This is the crux.  The namespace URI will end up having lots of associated 
data.  A schema is one example.  HTML documentation is another.  Come to 
that, Schemas Version 2 in a few years time.  The problem of associating 
information with a namespace needs a more general solution.

This solution, morever, should be catalogue based, not derived from markup 
in the document itself.  The fact that a namespace is documented in some 
http://whatever file is a property of the namespace, not of the particular 
use of the namespace in some XML document.
Received on Thursday, 18 May 2000 07:01:32 UTC

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