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From Alexander Dutton <>
Subject Re: Jena and PostGIS (à la LARQ)
Date Tue, 13 Sep 2011 15:14:29 GMT

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On 13/09/11 15:52, Paolo Castagna wrote:
> Which kind of queries you would like/need to run?

Probably just (non-BB) containment and distance to start with.

> Ideally, it would be good to have something pure Java which keeps
> things very simple to install. Ideally, zero installation cost:
> download, unzip, load data, run (as it is for Fuseki).

I agree. I've previously done some GeoDjango stuff, and even just
creating the PostGIS DB template was 'fun'. The minimum requirement
would be to set up a blank Postgres DB, provide {host, user, password}
details in the assembly and have it take it from there…

> What would be the best way to integrate|use such extensions into
> Fuseki? Ideally, with 0 changes to Fuseki code base... is that
> currently possible?

I've previously written a custom describe handler that IIRC uses
ja:loadClass to hook itself in, so it's certainly possible…

> Also, I have not been following the progress around GeoSPARQL:
> ... is
> there anything interesting/relevant there? Code? :-)

Me neither, I'm afraid.

> Finally, things to think about are:
> - how to you initially build your geo indexes [and] keep those
> indexes up-to-date as you add/remove triples|quads?

I would be happy with a manual cmd (again, following how LARQ does it
atm). Mind you, our data changes infrequently, so I'm happy for them
to get out-of-sync for short periods. Other people might be less happy ;).

Does Fuseki/TDB currently fire off some kind of signal when updates

> Ideally, I'd like to have a way to add property functions to ARQ
> (and use them with TDB datasets or Fuseki) without changing ARQ or
> TDB nor Fuseki source code. You drop a jar in your class path and
> the property function as well as keeping indexes up-to-date is
> there.

Is this not possible with the ja:loadClass approach?

- - Alex

- -- 
Alexander Dutton
Metamorphoses Project Developer, Claros
Oxford University Computing Services, ℡ 01865 (6)13483
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