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Re: Are *relative* URIs as namespace nemes considered harmful?

From: Liam Quin <liam@holoweb.net>
Date: Tue, 23 May 2000 17:31:11 -0400
To: xml-uri@w3.org
Message-ID: <20000523173111.A56490@dirk.holoweb.net>
James wrote, incorrectly:
> That's not the problematic case.  The problematic case is when you have
> two URI references that are identical when compared as strings but refer
> to different resources (because they have different base URIs).

URLs (specifically) do not guarantee that they will return teh
same octet stream when accessed each time. Many do not, in fact.

Therefore, there is *never* a guarantee that two URLs refer
to the same resource.  Consider a URL that, when dereferenced,
returns a random web page.  Or a document that is updated.

The only way to say that two URLs refer to the same thing is
to download them and look at what you got.  There is nothing else.

As a result, the only rational way forward is to define what lies
at the other end of a namespace URL, and to remind implementors
that they can use a cache to avoid fetching it every week, along
with the "Expires" http header where available.

If you do this, there is no long a problem with a relative URL,
because all that matters is the resource to which that URL refers,
not the byte sequence in the URL itself.


Liam Quin - Barefoot in Toronto - liam@holoweb.net - http://www.holoweb.net/
Ankh on irc.sorcery.net http://valinor.sorcery.net/
Co-author, The XML Specification Guide, Wiley, 1999
Forthcoming: The Open Source XML Database Toolkit
Received on Tuesday, 23 May 2000 17:31:12 UTC

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