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Re: Microformats and URI based extensibility

From: Harry Halpin <hhalpin@ibiblio.org>
Date: Fri, 28 Sep 2007 10:19:21 -0400
Message-ID: <46FD0D69.10308@ibiblio.org>
To: David Orchard <dorchard@bea.com>
Cc: www-tag <www-tag@w3.org>

David Orchard wrote:
> Tantek has written a page on the microformats wiki where he explains
> how microformats are a URI based form of extensibility and how the
> generic terms are scoped to within a root element.
> It's at http://microformats.org/wiki/misconceptions

The grounding of microformats is of course of interest to GRDDL, which
crucially relies on profile URIs as defined by XHTML 1, i.e. using a
@profile attribute to discover a profile that in turn has the
transformation needed to extract RDF from XHTML. This is a great
use-case of "follow-your-nose" in action, and it's even mentioned
explicitly by on the web-page about "misconceptions"[1].

However, besides hCard and XFN, almost no microformats *have* profile
URIs, and many tools don't use them. The reason is two-fold. First,
no-one has created profile URIs for other microformats. However, it is
possible if some one created a series of profile URIs for microforamts,
the microformat community would accept them. Would the W3C be willing to
host such profile URIs?

 Another excuse is that using a @profile URI requires access to the head
element, which some tools  (like cutting and pasting HTML code into HTML
created by an automatic microformat generator) cannot assume.

This situation is made worse by the fact that it appears that the XHTML2
WG wishes to deprecate @profile URIs in the head, and then move the
profile to be under a "link" element. Furthermore, there is movement
within the HTML 5 WG to deprecate any notion of @profile as well. Of
course, the GRDDL WG has sent e-mails to both WGs asking to maintain
@profile on WebArch principles, and perhaps some nudge from the TAG
might help our case if the TAG considers URI-based extensibility to be

One possible "work-around" for profile URIs for microformats would be to
let the "profile URI" of microformats that do not use a profile URI be
the HTML namespace [2],and so ground them in the HTML URI space itself.
This is politically tricky since so many groups have their fingers in
that namespace and the process for altering it is a bit unclear to me.
For example, putting GRDDL transformations for microformts like
"rel-tag" in the HTML namespace would make them GRDDL-compatible.


[1] http://microformats.org/wiki/misconceptions
In particular: "The XMDP spec (http://gmpg.org/xmdp/description) and the
GRDDL (http://www.w3.org/2003/g/data-view) spec show how to make a
profile, and how generic data clients to follow, to either ground the
data into RDF, or use the data directly as microformats with terms
defined by their XMDP+ID URIs. This will maximize re-use of the data, in
combination wit other data. There is a growing class of grddl-aware
systems (http://esw.w3.org/topic/GrddlImplementations) which will use
GRDDL-enabled microformat data without any alteration."

[2] http://www.w3.org/1999/xhtml/

> Cheers,
> Dave


Harry Halpin,  University of Edinburgh 
http://www.ibiblio.org/hhalpin 6B522426
Received on Friday, 28 September 2007 14:19:45 UTC

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