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Official Response to ISSUE-121 from RDF Web Apps WG

From: Manu Sporny <msporny@digitalbazaar.com>
Date: Sat, 28 Jan 2012 13:47:39 -0500
Message-ID: <4F2442CB.2090005@digitalbazaar.com>
To: Sebastian Heath <sebastian.heath@gmail.com>
CC: RDFa WG <public-rdfa-wg@w3.org>
Hi Sebastian,

Thank you for your public feedback on the RDFa 1.1 documents. This is an
official response from the RDF Web Apps WG to your issue before we enter
the 3rd Last Call for the RDFa 1.1 work this coming Tuesday. The Last
Call will last for 3 weeks, so there is still time for you to discuss
your concerns if we have not fully addressed them.

Your issue was tracked here:

ISSUE-121: Using @id to set subject in RDFa
https://www.w3.org/2010/02/rdfa/track/issues/121

Explanation of Issue
--------------------

You had wanted us to consider allowing @id attribute to set the subject
when @typeof existed on the same element:

"""
Currently, RDFa processors do not take account of @id attributes in
host-languages. In particular, in (x)html the @id attribute is
ignored. In (x)html, this creates unnecessary complication in which
the value in @id needs to be prefixed by '#' and put in an @about
attribute in order to make semantic markup visible to both html agents
and rdfa processors.

Example:

  <p id="item1" typeof="ex:item" about="#item1">
    <span property="item_name">An interesting item (1)</span>
  </p>

I suggest that a combination of @typeof and @id cause the subject to
be set to the fully qualified URL implied by the value @id, according
to normal URL processing rules defined for HTML and related languages.
"""

Working Group Decision
----------------------

The Working Group had considered allowing this very early in the RDFa
1.0 days and decided that @id by itself would generate far too many junk
triples in the output. We re-opened the issue because we did not believe
that we had discussed @typeof and @id being used in concert to create a
triple. The full discussion can be found here:

http://www.w3.org/2010/02/rdfa/meetings/2011-12-08#ISSUE__2d_121__3a__Use___40_id_to_set_the_subject_in_RDFa

The WG felt that the following issues prevent us from adopting what you
propose:

1. There are a slew of non-trivial HTTP-Range-14 issues about which
    namespace @id refers to and which namespace @about refers to that
    would be raised. Document identifiers mixing with semantic item
    identifiers would be problematic at best.
2. It would break existing documents that use @typeof and @id on the
    same document.
3. It would make RDFa more complicated than it already is.
4. There are no compelling use cases - that is, most use cases can
    already be addressed using the attributes that exist right now.

So, in the end, the WG did the following:

RESOLVED: The @id attribute MUST NOT be used to identify a subject in RDFa.

http://www.w3.org/2010/02/rdfa/meetings/2011-12-08#resolution_4

Feedback
--------

Since this is an official Working Group response to your issue, we would
appreciate it if you responded to this e-mail and let us know if the
decision made by the group is acceptable to you as soon as possible.

-- manu

-- 
Manu Sporny (skype: msporny, twitter: manusporny)
Founder/CEO - Digital Bazaar, Inc.
blog: PaySwarm vs. OpenTransact Shootout
http://manu.sporny.org/2011/web-payments-comparison/
Received on Saturday, 28 January 2012 18:48:19 UTC

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