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calendars in RDF and HTML: implicit/default values

From: Dan Connolly <connolly@w3.org>
Date: Fri, 21 Apr 2006 14:42:32 -0500
To: Ben Adida <ben@mit.edu>
Cc: www-archive@w3.org, "Ralph R. Swick" <swick@csail.mit.edu>, Eric Miller <em@w3.org>
Message-Id: <1145648552.27608.688.camel@dirk.w3.org>

Thinking about RDF/A and GRDDL in concrete terms...

One of the things that makes RDF/XML hard to deal with
is that you can make up a vocabulary of terms, but
you can't play any syntax tricks beyond that. You can't
have defaults or syntactic shortcuts.

In fromIcal.py, when we convert from .ics format
to RDF, we fill in the defaults:

    # fill in defaults
    if not obj.has_key('interval'):
        obj['interval'] = 1

(it's actually in
http://www.w3.org/2002/12/cal/icslex.py )

I haven't implemented that in glean-hcal.xsl, but
I have implemented things like "if the datetime
value ends with a Z, use a different datatype".

In fact, glean-hcal.py implements UTC offsets.
So you can write
  <abbr class="dtend" title="2006-04-25T09:50:00+0200">0950</abbr>

and in the .rdf , it ends up as:

<c:dtend
r:datatype="http://www.w3.org/2001/XMLSchema#dateTime">2006-04-25T11:50:00Z</c:dtend>

Another one is that <abbr class="geo" title="lat;long">...</>
gets split into 2 properties.

As far as I can tell, RDF/A is subject to all the constraints that
RDF/XML is, in this respect. You can use any URI-terms you want
(and bnodes and literals) but you can't play syntactic shortcut
tricks the way you can with an XSLT transformation.

I thought we could sorta enhance RDF/A so that it just happens
to include hCalendar and hCard syntax, but there's a remarkable
amount of domain-specific stuff in the syntactic details.

I think it's feasible to find some middle ground between RDF/A
and Embedded RDF for encoding RDF graphs in general, but I still
think we're going to need specific syntactic support for important
classes of information like calendars.

-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
D3C2 887B 0F92 6005 C541  0875 0F91 96DE 6E52 C29E
Received on Friday, 21 April 2006 19:42:37 GMT

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