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Re: [XRI] XRI-as-Relative-URI proposal (ACTION-189 refers)

From: Henry S. Thompson <ht@inf.ed.ac.uk>
Date: Thu, 13 Nov 2008 11:40:55 +0000
To: "Drummond Reed" <drummond.reed@cordance.net>
Cc: <www-tag@w3.org>, "'Peter Davis'" <peter.davis@neustar.biz>, <jbradley@mac.com>
Message-ID: <f5bbpwjj1ko.fsf_-_@hildegard.inf.ed.ac.uk>

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Drummond Reed writes:

> [There's] a new proposal for how XRIs can better fit with AWWW
> architecture.
> . . .
> The proposal is written up on an XRI TC wiki page at:
>
> 	http://wiki.oasis-open.org/xri/XriAsRelativeUri


I've looked at this in some detail, and agree with others' comments
that it looks like a very good direction to move in.

I think the clarifications that have emerged in this thread wrt what
you call the concrete/abstract distinction are important, and should
be included, very carefully, in the eventual full specification.

I have two remaining concerns:

 1) Very little is said about where the necessary base URIs are going
    to come from.  This is almost certainly corrigible going forward,
    that is, in a new specification, although it will have to be done
    carefully, and, I hope, with reference to either the Infoset [base
    URI] property [1] or XML Base [2] insofar as XML-expressed
    languages are concerned.  Retrospective cleanup, for example wrt
    OpenID's usage of 'short' old-style XRIs such as =jbradley, will
    be more challenging, but should none-the-less be attempted I
    think.

 2) I think the list of candidate schemes which may be used in
    XRI-signalling base URIs is too ambitious, unnecessarily so as far
    as I can see.  Including e.g. ftp: is surely to miss the 80-20
    point by a long way.  More seriously, including urn: is a big
    mistake.  There is no well-defined notion of relative URN, or of
    absolutisation for URNs.  URNs are not what RFC 3986 calls
    'hierarchical identifiers', and the RFC says explicitly [3]:

       "relative references can only be used within the context of a
        hierarchical URI"

    Please just don't go there!

ht

[1] http://www.w3.org/TR/xml-infoset/#infoitem.element
[2] http://www.w3.org/TR/xmlbase/
[3] http://www.apps.ietf.org/rfc/rfc3986.html#sec-1.2.3
- -- 
       Henry S. Thompson, School of Informatics, University of Edinburgh
                         Half-time member of W3C Team
      10 Crichton Street, Edinburgh EH8 9AB, SCOTLAND -- (44) 131 650-4440
                Fax: (44) 131 651-1426, e-mail: ht@inf.ed.ac.uk
                       URL: http://www.ltg.ed.ac.uk/~ht/
[mail really from me _always_ has this .sig -- mail without it is forged spam]
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Received on Thursday, 13 November 2008 11:41:43 GMT

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