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Re: RDF Visualization

From: Eric Prud'hommeaux <eric@w3.org>
Date: Mon, 19 Aug 2002 09:44:12 -0400
To: Dan Brickley <danbri@w3.org>
Cc: Paul Prescod <paul@prescod.net>, www-rdf-validator@w3.org
Message-ID: <20020819094412.A2927@w3.org>

On Mon, Aug 19, 2002 at 01:30:25AM -0400, Dan Brickley wrote:
> +cc:eric@w3.org (re perllib parser)
> 
> Hi Paul,
> 
> On Sun, 18 Aug 2002, Paul Prescod wrote:
> > This works nicely but it uses POST not GET so I don't get a nice
> > GET-table URI which was my goal from the start. I want to be able to
> > point people at a URI where all they have to do is hit a button or even
> > better not even have to hit the button.
> 
> I *think* the servlet might be GET-happy, although the submission form isn't.
> 
> One RESTy issue here: running the visualiser creates a new resource
> (ie. the downloadable image file(s) from graphviz). Currently these get
> zapped periodically to avoid filling up limited disk resources. If the
> service was made to expose GET, we'd need to hack the servlet to
> transparently re-run graphviz if the cache'd output of the visualiser had
> been deleted. And we might get religious about whether GET was appropriate
> since it involves server-side changes. My hunch is that GET would be fine,
> since the server-side change is an optimisation, but I'm not 100% sure.

Ephemoral objects are allowed in the REST model, but the referring
entity (the RDF Visualizer) ought not be cached beyond the life of the
zapped referent. If you have no way of predicting this, you could move
the image generation to your own machine:
  algae -sClassdot -o foo.dot | dot -Tpng -o foo.png foo.dat

> >
> > #2:
> >
> > So I go back to the beginning and try some other data at rdfviz.org
> >
> >  * http://www.oreillynet.com/meerkat/?_fl=rss10
> >
> > I guess it can't parse that document. (it must not use a real XML
> > parser???)
> 
> >From a brief look, it seems to be a problem with entities.  I'm running an
> old version of EricP's Perllib RDF and XML parser.

Depending on the age, it might have the -p option to specify the
parser.  `-p W3C::SAX::ExpatXmlParser` specifies Expat. The default is
W3C::SAX::PerlXmlParser which does not support entities.

> >  *
> > http://snowball.ilrt.bris.ac.uk/rdf-viz/out/rdfviz-2002-08-19:37-2-46.rtab
> >
> > Anyhow, once I gave up on a GET interface, I just resigned myself to
> > cutting and pasting into the code text box and the SirPAC version works
> > well.
> 
> Yup, ARP seems pretty complete.
> 
> Sorry you had such a bumpy ride with all this Paul. I ought to take more
> care to gracefully retire old services, instead of leaving them hanging
> around where they can cause annoyance.
> 
> Best place to start for RDF visualisation at W3C is
> http://www.w3.org/RDF/Validator -- I hear there's a more i18n version in
> the pipeline too...
> 
> thanks for your patience and for the feedback,
> 
> Dan
> 

-- 
-eric

(eric@w3.org)
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Received on Monday, 19 August 2002 09:44:17 GMT

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