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Re: RDF/XML Syntax Specification (Revised) W3C Working Draft published

From: Dave Beckett <dave.beckett@bristol.ac.uk>
Date: Wed, 19 Dec 2001 13:48:14 +0000
To: Roland Schwaenzl <Roland.Schwaenzl@mathematik.Uni-Osnabrueck.DE>
cc: mmoran@netphysic.com, www-rdf-interest@w3.org
Message-ID: <27142.1008769694@tatooine.ilrt.bris.ac.uk>
>>>Roland Schwaenzl said:
> > >   - it is not used
> 
> we do....

I didn't write that summary, but would have said: it is not widely
used correctly.  Mostly due to the subsequent reasons

> > >   - it is not widely implemented
> 
> you're sure? 

Pretty much.  Again, it is not widely implemented completely and
correctly, mostly due to the reasons below - confusion and
difficulty.  I think there are around 1-2 complete and correct
implementations; most RDF systems either by default don't support it
except with some special flags, or don't support it at all.

I did a good look around when researching this issue and you can read
the things I found here:
  http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2001Nov/0470.html
where I looked at a dozen RDF systems or so for evidence.

> 
> > >   - it has confusing interactions with rdf:bagID
> > >   - it does not scale as parsers have to save state
> > >   - this is the wrong layer in which to implemenent such functionality
> 
> which layer is better in the view of rdf-core?

Layers above RDF where the data model has the notion of distributed
referrents so that it is more than just a syntax thing.  For example,
DAML+OIL has such things and CWM has log:forall that can do this too.

<snip/>

I quite like what Dan Brickey said during the RDF Core WG discussion:

  I for one will never enourage people to write down useful
  generalisations in aboutEach syntax, because I don't want to have
  them come back and ask me why those rules aren't accessible via the
  (graph-oriented) APIs, query languages, database interfaces etc
  that they'll have to use to access their content. In my experience
  of talking to RDF developers _and_ content producers, there's often
  misunderstanding about which features of the XML syntax are carried
  through to the abstract graph. So my problem with encouraging the
  use of aboutEach is that it risks creating a huge legacy problem:
  information loss as we go from the RDF/XML into databases, APIs
  etc. Because about aboutEach mechanism _appears_ to be RDF's way of
  making generalised claims about members of a collection, people
  will likely use it as such unless we attach a health warning. Once
  it becomes clear that aboutEach is just a wierd macro mechanism, I
  believe it'll lose its appeal to content producers.

  -- http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2001Nov/0532.html

Dave
Received on Wednesday, 19 December 2001 08:48:20 GMT

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