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

Re: When are two URIs equivalent?

From: Eric van der Vlist <vdv@dyomedea.com>
Date: Tue, 23 May 2000 16:43:42 +0200
Message-ID: <392A991E.E219BA55@dyomedea.com>
To: xml-uri@w3.org
So the confusion was between "comparing absolutized URI references"
which you are explaining below and is described in RFC 2396, chapter 5
and URI normalization and equivalence quoted by Josef which is chapter

Absolutization isn't scheme dependent while normalization is and may
even require network access.



keshlam@us.ibm.com wrote:
> Note that string equality works for URIs ... but (arguably) not for URI
> References. It is argued that they should be compared after being converted
> into absolute URIs.
> The process for doing so is described in the RPC which describes URI
> References; basically, it says that if the URI Reference is relative it
> should be combined with the base URI in effect at that point, and that any
> /. and /..  should be resovled (by removing /., and by removing /..
> together with the last /-delimited section of the base URI).
> Note that /. and /.. are only removed if the original reference was
> relative. If it was absolute, the absolutizing code leaves them alone. Thus
> "http://foo/bar/./baz/../murph" is left unchanged by this process; it is
> _not_ considered the same URI as "http://foo/bar/murph" even after
> absolutizing.
> Also note that character escapes are _not_ converted by this process.
> "http://foo/%61" is left unchanged; it is _not_ considered the same URI as
> "http://foo/a"  even after absolutizing.
> Reminder: We have not yet agreed on whether Namespace Names are or aren't
> URI References. The Namespace spec currently says they are URI Refs but
> that they're compared as literal strings, which some folks feel is a
> conflict. The question is which of the three portions of that statement
> should be considered an error:
> LITERAL: That they _are_ URI references, as opposed to being expressed in
> reference syntax.
> FORBID: That they are URI _references_ (which can be relative) as opposed
> to URIs (which can't).
> ABSOLUTIZE: That they are compared as literals.
> ______________________________________
> Joe Kesselman  / IBM Research

Eric van der Vlist       Dyomedea                    http://dyomedea.com
http://xmlfr.org         http://4xt.org              http://ducotede.com
Received on Tuesday, 23 May 2000 10:42:31 UTC

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