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Re: Finding SPARQL endpoints

From: Hugh Glaser <hg@ecs.soton.ac.uk>
Date: Wed, 2 Oct 2013 12:41:01 +0000
To: Michael Brunnbauer <brunni@netestate.de>
CC: Hugh Glaser <hg@ecs.soton.ac.uk>, "semantic-web@w3.org" <semantic-web@w3.org>, "py.vandenbussche@gmail.com" <py.vandenbussche@gmail.com>
Message-ID: <A8B5F0DA-0951-4EA0-A937-E90487C9F314@soton.ac.uk>
Apropos rkb.*
Almost all the rkb stores are on the same technology, so it was the fact that some worked and some didn't that was strange.
It seems that some challenging queries or something had screwed up stores like citeseer a bit - they worked for what I tried, but not for that.
Thanks - I've hopefully sorted them.
They are actually based on http://www.w3.org/2001/sw/wiki/3Store , which hasn't been updated since 2008-04-09!, and was only ever meant as a proof of concept.
So you can probably work out which version of SPARQL they implement - more than 5 years ago.
But in fact they do support Graph, but not things like COUNT, as I recall.
Best
Hugh
On 2 Oct 2013, at 12:56, Michael Brunnbauer <brunni@netestate.de>
 wrote:

> 
> Hello Hugh,
> 
> On Tue, Oct 01, 2013 at 04:29:50PM +0000, Hugh Glaser wrote:
>> Did you know about http://labs.mondeca.com/sparqlEndpointsStatus/ ?
>> If so, can you give us some idea of the different sets or whatever please - I think they have 480 endpoints.
>> Maybe you could helpfully collaborate with Pierre-Yves to get a more comprehensive list between you?
> 
> I see that http://labs.mondeca.com/endpoint/ends is not in my list and will
> rerun my query with that additional endpoint. This should add those 480 
> endpoints to the list - if not already there.
> 
> Unfortunately, my query does not work any more after an update of Fuseki.
> I will have to check if the bug is in the new version or in the old version
> and in my SPARQL query.
> 
>> I notice that quite a few of the (RKB) endpoints are listed as "no", when they are in fact up, and have been all the time.
> 
> Can you give an example ?
> 
> My measurement method is sending this via federation:
> 
> select ?p where { { ?s ?p ?o } UNION { GRAPH ?g1 { ?s ?p ?o } } } limit 1
> 
> It will not work if the endpoint requires authentication or redirects to a new
> endpoint URL. The named graph part of the query also seems to be unsupported
> by some endpoints. For example, http://citeseer.rkbexplorer.com/sparql/ will
> give me this error message: 
> 
> SQL error in 'CREATE /* TMP */ TABLE uit (bm integer NOT NULL) 
> 
> Should I remove the named graph part ? How many endpoints are there in the 
> wild containing useful information in named graphs ?
> 
> Regards,
> 
> Michael Brunnbauer
> 
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Received on Wednesday, 2 October 2013 12:42:27 UTC

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