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ISSUE-1: What happens when you can't dereference a profile document?

From: Manu Sporny <msporny@digitalbazaar.com>
Date: Thu, 11 Mar 2010 12:37:08 -0500
Message-ID: <4B992A44.5030908@digitalbazaar.com>
To: RDFa WG <public-rdfa-wg@w3.org>
"What happens when you can't dereference the profile document?"

Both Ben and Toby have been concerned about what happens when you cannot
dereference an RDFa Profile document. Both of them have expressed that
he would like to see a placeholder triple that is generated when a
profile document cannot be dereferenced. RDFa toolchains can then
dereference the profile document at a later time and re-write the triple
when the profile document becomes available.

So this:

<div profile="http://example.com/unavailable" property="foo">Bar</div>

would generate the following triples when the "unavailable" profile
cannot be dereferenced, perhaps in another RDF graph:

<>
   <http://example.com/unavailable#foo>^^DEREFERENCE_LATER
      "Bar" .

When the triple is de-referenced later, if the value doesn't appear in
the profile, the triple is discarded. Note that we may need a new
resource type to get this to work. If there are multiple profiles, you
generate multiple triples - one for each profile.

Toby has an alternate mechanism that uses @default-prefix and requires
RDFa processors to understand a subset of OWL. The proposal is explained
in more depth here:

http://lists.w3.org/Archives/Public/public-rdf-in-xhtml-tf/2010Jan/0019.html

Some argue that neither one of these approaches are necessary and that
they overly-complicate RDFa. If you can't dereference a profile
document, you keep processing. We could make RDFa Processors throw a
"Profile unavailable exception", which would allow applications to not
use any triples generated on the page... or make the decision to use all
triples before the "Profile unavailable exception". This approach seems
to fit with the way the web works now: If you can't dereference a URL,
too bad, try to keep going.

-- manu

-- 
Manu Sporny (skype: msporny, twitter: manusporny)
President/CEO - Digital Bazaar, Inc.
blog: PaySwarming Goes Open Source
http://blog.digitalbazaar.com/2010/02/01/bitmunk-payswarming/
Received on Thursday, 11 March 2010 17:37:36 GMT

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