Re: Fixed base

At the time that John Cowan first proposed this, I was struck by an 
additional thought that I suggested only privately, as I didn't 
expect that even a fixed-base proposal would fly.

We can almost entirely preserve literal comparison by using a base 
URI that is the null string. In this case, relative URI references 
absolutize to syntactically illegal absolute URIs. This means that 
it's crystal clear that they aren't suitable for retrieval, since 
they're not legal absolure URIs.

They can be compared just fine, however, so the namespace 
identification function is not impaired.

Because internal occurrences of ../ and ./ can be rewritten, it's not 
identical to the current namespace spec, but the chances of causing 
problems are vanishingly small.

Your proposal is fine by me, though. It's quite clear that the 
"contextdependent:" scheme can be interpreted by any application any 
way that it wants to, and that anyone that actually wants a 
retrievable name must use an absolute URI.

    -- David

At 12:50 PM +0700 6/20/00, James Clark wrote:
>I've been quite surprised to find that this debate has actually
>changed my views.  I now believe the right solution is to absolutize
>namespace names relative to a fixed base URI of something like
>"contextdependent:/" and then perform a character-for-character
>comparison (I'll call this solution "fixed base" for short).  Several
>people have already voiced their support for similar proposals:
>
>    http://lists.w3.org/Archives/Public/xml-uri/2000Jun/0347.html
>    http://lists.w3.org/Archives/Public/xml-uri/2000Jun/0601.html
>    http://lists.w3.org/Archives/Public/xml-uri/2000Jun/0647.html
>
>The effect of "fixed base" is very similar to the "literal" solution;
>except for URIs containing "." and ".." it will be the same.  However,
>it avoids the key problem of the "literal" approach: with "fixed base"
>there's never a case where two URIs are namespace equal but refer to
>different resources; thus an application such as RDF that needs to
>dereference namespace URIs can be consistently layered on top of
>"fixed base".  It also avoids the key problem with the "deprecate"
>solution, which is to specify what happens when documents use relative
>namespace URIs despite their being deprecated.
-- 
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David Durand              dgd@cs.bu.edu  \  david@dynamicDiagrams.com
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Received on Tuesday, 20 June 2000 12:20:05 UTC