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

Re: When are 2 URI's the same?

From: <keshlam@us.ibm.com>
Date: Fri, 19 May 2000 11:17:16 -0400
To: "Anthony B. Coates, ESL +61 2 9373 7972 Sydney" <tony.coates@reuters.com>
cc: xml-uri@w3.org
Message-ID: <852568E4.0053FACF.00@D51MTA03.pok.ibm.com>
>When are two URI's the same?

When they're the same string. Really.

>When do two relative URI's refer to the same thing?

There's no such thing as a relative URI.

Relative URI _References_ are the same when absolutizing them in terms of
the appropriate base URI yields the same string.

However, two URI References whcih are not "the same" may refer to the same
data after they have been canonicalized. For example, expansion of
character escapes, or relative references embedded deeper in the URI, or
server-side processing of the URI (directory links and so on) may all cause
two URIs which are formally different to point to the same resource.

>If they are compared as strings, surely the spec should say
>that namespace identifiers are strings, and are not URI's, even if
>they often look like URI's.

We've been told by folks who participated in the Namespace design that this
was the intent. The statement that they're to be compared literally
confirms this. The statement that the values "are" URIs was an editing

The debate now raging is between those who want to correct the conflict by
preserving the intended meaning, those who want to correct the conflict by
adopting the typo, and those who want to eliminate the problem by
forbidding any syntax which exposes differences between the other two

That should give you enough background to start evaluating the conflicting
demands and proposals...
Received on Friday, 19 May 2000 11:17:43 UTC

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