W3C home > Mailing lists > Public > semantic-web@w3.org > April 2007

Re: xml:base (was Re: IRI meets RDF meets HTTP redirect)

From: John Cowan <cowan@ccil.org>
Date: Thu, 19 Apr 2007 11:14:49 -0400
To: Jeremy Carroll <jjc@hpl.hp.com>
Cc: John Cowan <cowan@ccil.org>, Sandro Hawke <sandro@w3.org>, semantic-web@w3.org, www-international@w3.org
Message-ID: <20070419151449.GL1262@mercury.ccil.org>

Jeremy Carroll scripsit:

> There is no inherent limit on the [base URI] Infoset property, 

The limit on it is that it's a URI.  There is no [base IRI] property,
and AFAIK no one has asked for one.

> motivating the restriction to URI rather than IRI. It seems to be a 
> requirement of a spec (XML Base?) that it be so.

Rather it is a requirement of the Infoset [base URI] property.
XML Base just specifies how to compute this property.

> Oh good. So a base-uri function, which doesn't do any fetching, also
> doesn't do any %-escaping?

If your base-uri function is expected to return a URI (that is, if it
returns the [base URI] property), then it had better do %-escaping.

Chris Lilley scripsit:

> I would need to spec-spelunk to be sure but that would be my interpretation
> of the intent of the PER, yes.
> 
> Specifically, two IRIs are the same if (following use of xml:base to do
> relative-to-absolute) they are the same Unicode strings.

XML Base, however, does not use the notion of IRI.  An implementation
of XML Base must behave as if it converted the xml:base attribute
value to a URI by expanding a subset of the %-escapes, and then 
did resolution in accordance with RFC 3986 (not 3987).

> SH> Of course, if you *want* the base end with "rÔ–’sumÔ–’" you're out of luck,
> SH> since XML Base [1] says you can only use a URI.
> 
> No, it doesn't.

[quotations from XML Base snipped]

Those quotations refer explicitly to the content of xml:base attributes;
they say nothing about the characters that can or cannot be in the
base URI.  Those are controlled by RFC 2396 (or 3986 in the PER).

The PER in no way changes the syntax or semantics of xml:base attributes,
only the way in which they are explained.

Note:  I'm a member of the XML Core WG, which owns the XML Base spec,
and I may speak in accordance with my best recollection of things
discussed there when making statements about intentions.  However,
I don't speak for the WG.

-- 
John Cowan    <cowan@ccil.org>     http://www.ccil.org/~cowan
But no living man am I!  You look upon a woman.  Eowyn I am, Eomund's daughter.
You stand between me and my lord and kin.  Begone, if you be not deathless.
For living or dark undead, I will smite you if you touch him.
Received on Thursday, 19 April 2007 15:15:25 GMT

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