Re: The truth about SPARQL Endpoint availability

2011-03-05 Thread Andrea Splendiani
Hi, very nice!
I have a small suggestion:

why don't you ask count(*) where {?s ?p ?o} to the endpoint ?
Or ask for the number of graphs ?
Both information, number of triples and number of graphs, if logged and 
compared over time, can give a practical view of the liveliness of the content 
of the endpoint.

best,
Andrea Splendiani


Il giorno 28/feb/2011, alle ore 18.55, Pierre-Yves Vandenbussche ha scritto:

 Hello all,
 
 you have already encountered problems of SPARQL endpoint accessibility ?
 you feel frustrated they are never available when you need them?
 you develop an application using these services but wonder if it is reliable?
 
 Here is a tool [1] that allows you to know public SPARQL endpoints 
 availability and monitor them in the last hours/days. 
 Stay informed of a particular (or all) endpoint status changes through RSS 
 feeds.
 All availability information generated by this tool is accessible through a 
 SPARQL endpoint.
 
 This tool fetches public SPARQL endpoints from CKAN  open data. From this 
 list, it runs tests every hour for availability.
 
 [1] http://labs.mondeca.com/sparqlEndpointsStatus/index.html
 [2] http://ckan.net/
 
 Pierre-Yves Vandenbussche.

Andrea Splendiani
Senior Bioinformatics Scientist
Centre for Mathematical and Computational Biology
+44(0)1582 763133 ext 2004
andrea.splendi...@bbsrc.ac.uk





Re: The truth about SPARQL Endpoint availability

2011-03-05 Thread Hugh Glaser
NIce idea, but,... :-)

SELECT (count(*) as ?c) WHERE {?s ?p ?o}

is a pretty anti-social thing to do to a store.
At best, a store of any size will spend a while thinking, and then quite 
rightly decide they have burnt enough resources, and return some sort of error.

For a properly maintained site, of course, the VoiD description will give lots 
of similar information.
Best
Hugh

On 5 Mar 2011, at 13:06, Andrea Splendiani wrote:

 Hi, very nice!
 I have a small suggestion:
 
 why don't you ask count(*) where {?s ?p ?o} to the endpoint ?
 Or ask for the number of graphs ?
 Both information, number of triples and number of graphs, if logged and 
 compared over time, can give a practical view of the liveliness of the 
 content of the endpoint.
 
 best,
 Andrea Splendiani
 
 
 Il giorno 28/feb/2011, alle ore 18.55, Pierre-Yves Vandenbussche ha scritto:
 
 Hello all,
 
 you have already encountered problems of SPARQL endpoint accessibility ?
 you feel frustrated they are never available when you need them?
 you develop an application using these services but wonder if it is reliable?
 
 Here is a tool [1] that allows you to know public SPARQL endpoints 
 availability and monitor them in the last hours/days. 
 Stay informed of a particular (or all) endpoint status changes through RSS 
 feeds.
 All availability information generated by this tool is accessible through a 
 SPARQL endpoint.
 
 This tool fetches public SPARQL endpoints from CKAN  open data. From this 
 list, it runs tests every hour for availability.
 
 [1] http://labs.mondeca.com/sparqlEndpointsStatus/index.html
 [2] http://ckan.net/
 
 Pierre-Yves Vandenbussche.
 
 Andrea Splendiani
 Senior Bioinformatics Scientist
 Centre for Mathematical and Computational Biology
 +44(0)1582 763133 ext 2004
 andrea.splendi...@bbsrc.ac.uk
 
 
 

-- 
Hugh Glaser,  
  Intelligence, Agents, Multimedia
  School of Electronics and Computer Science,
  University of Southampton,
  Southampton SO17 1BJ
Work: +44 23 8059 3670, Fax: +44 23 8059 3045
Mobile: +44 78 9422 3822, Home: +44 23 8061 5652
http://www.ecs.soton.ac.uk/~hg/





Re: The truth about SPARQL Endpoint availability

2011-03-05 Thread Andrea Splendiani
Hi,

I think it depends on the store, I've tried some (from the endpoint list) and 
some returns a answer pretty quickly. Some doesn't and some doesn't support 
count.
However, one could have this information only for the stores that answers the 
count query, no need to try all time.

VoID:
is this a good query:
select * where {?s http://rdfs.org/ns/void#numberOfTriples ?o } 

it doesn't seem viable if so.

ciao,
Andrea


Il giorno 05/mar/2011, alle ore 13.49, Hugh Glaser ha scritto:

 NIce idea, but,... :-)
 
 SELECT (count(*) as ?c) WHERE {?s ?p ?o}
 
 is a pretty anti-social thing to do to a store.
 At best, a store of any size will spend a while thinking, and then quite 
 rightly decide they have burnt enough resources, and return some sort of 
 error.
 
 For a properly maintained site, of course, the VoiD description will give 
 lots of similar information.
 Best
 Hugh
 
 On 5 Mar 2011, at 13:06, Andrea Splendiani wrote:
 
 Hi, very nice!
 I have a small suggestion:
 
 why don't you ask count(*) where {?s ?p ?o} to the endpoint ?
 Or ask for the number of graphs ?
 Both information, number of triples and number of graphs, if logged and 
 compared over time, can give a practical view of the liveliness of the 
 content of the endpoint.
 
 best,
 Andrea Splendiani
 
 
 Il giorno 28/feb/2011, alle ore 18.55, Pierre-Yves Vandenbussche ha scritto:
 
 Hello all,
 
 you have already encountered problems of SPARQL endpoint accessibility ?
 you feel frustrated they are never available when you need them?
 you develop an application using these services but wonder if it is 
 reliable?
 
 Here is a tool [1] that allows you to know public SPARQL endpoints 
 availability and monitor them in the last hours/days. 
 Stay informed of a particular (or all) endpoint status changes through RSS 
 feeds.
 All availability information generated by this tool is accessible through a 
 SPARQL endpoint.
 
 This tool fetches public SPARQL endpoints from CKAN  open data. From this 
 list, it runs tests every hour for availability.
 
 [1] http://labs.mondeca.com/sparqlEndpointsStatus/index.html
 [2] http://ckan.net/
 
 Pierre-Yves Vandenbussche.
 
 Andrea Splendiani
 Senior Bioinformatics Scientist
 Centre for Mathematical and Computational Biology
 +44(0)1582 763133 ext 2004
 andrea.splendi...@bbsrc.ac.uk
 
 
 
 
 -- 
 Hugh Glaser,  
  Intelligence, Agents, Multimedia
  School of Electronics and Computer Science,
  University of Southampton,
  Southampton SO17 1BJ
 Work: +44 23 8059 3670, Fax: +44 23 8059 3045
 Mobile: +44 78 9422 3822, Home: +44 23 8061 5652
 http://www.ecs.soton.ac.uk/~hg/
 
 

Andrea Splendiani
Senior Bioinformatics Scientist
Centre for Mathematical and Computational Biology
+44(0)1582 763133 ext 2004
andrea.splendi...@bbsrc.ac.uk






Re: The truth about SPARQL Endpoint availability

2011-03-05 Thread Hugh Glaser
Hi,
On 5 Mar 2011, at 14:22, Andrea Splendiani wrote:

 Hi,
 
 I think it depends on the store, I've tried some (from the endpoint list) and 
 some returns a answer pretty quickly. Some doesn't and some doesn't support 
 count.
 However, one could have this information only for the stores that answers the 
 count query, no need to try all time.
I am happy for a store implementor or owner to disagree, but I find it very 
unlikely that the owner of a store with a decent chunk of data ( 1M triples, 
say) would be happy for someone to keep issuing such a query, even if they did 
decide to give enough resources to execute it.
I would quickly blacklist such a site.
 
 VoID:
 is this a good query:
 select * where {?s http://rdfs.org/ns/void#numberOfTriples ?o } 

I'm no SPARQL or voiD guru, but I think you need a bit more wrapping in the 
scovo stuff, so more like:

SELECT DISTINCT ?endpoint ?uri ?triples ?uris WHERE
   { ?ds a void:Dataset .
 ?ds void:sparqlEndpoint ?uri .
 ?ds rdfs:label ?endpoint .
 ?ds void:statItem [ scovo:dimension void:numberOfTriples ; 
rdf:value  ?triples ] .
  }

Try it at
http://kwijibo.talis.com/voiD/
or
http://void.rkbexplorer.com/

I guess Pierre-Yves might like to enhance his page by querying a voiD store to 
also give basic stats.
Or someone might like to do a store reporter that uses (a) voiD endpoint(s) 
plus Pierre-Yves's data (he has a SPARQL endpoint), to do so.
And maybe the CKAN endpoint would have extra useful data as well.
A real Semantic Web application that queried more than one SPARQL endpoint - 
now that would be a novelty!
Fancy the challenge, it is the weekend?! :-)

ciao
Hugh

 
 it doesn't seem viable if so.
 
 ciao,
 Andrea
 
 
 Il giorno 05/mar/2011, alle ore 13.49, Hugh Glaser ha scritto:
 
 NIce idea, but,... :-)
 
 SELECT (count(*) as ?c) WHERE {?s ?p ?o}
 
 is a pretty anti-social thing to do to a store.
 At best, a store of any size will spend a while thinking, and then quite 
 rightly decide they have burnt enough resources, and return some sort of 
 error.
 
 For a properly maintained site, of course, the VoiD description will give 
 lots of similar information.
 Best
 Hugh
 
 On 5 Mar 2011, at 13:06, Andrea Splendiani wrote:
 
 Hi, very nice!
 I have a small suggestion:
 
 why don't you ask count(*) where {?s ?p ?o} to the endpoint ?
 Or ask for the number of graphs ?
 Both information, number of triples and number of graphs, if logged and 
 compared over time, can give a practical view of the liveliness of the 
 content of the endpoint.
 
 best,
 Andrea Splendiani
 
 
 Il giorno 28/feb/2011, alle ore 18.55, Pierre-Yves Vandenbussche ha scritto:
 
 Hello all,
 
 you have already encountered problems of SPARQL endpoint accessibility ?
 you feel frustrated they are never available when you need them?
 you develop an application using these services but wonder if it is 
 reliable?
 
 Here is a tool [1] that allows you to know public SPARQL endpoints 
 availability and monitor them in the last hours/days. 
 Stay informed of a particular (or all) endpoint status changes through RSS 
 feeds.
 All availability information generated by this tool is accessible through 
 a SPARQL endpoint.
 
 This tool fetches public SPARQL endpoints from CKAN  open data. From this 
 list, it runs tests every hour for availability.
 
 [1] http://labs.mondeca.com/sparqlEndpointsStatus/index.html
 [2] http://ckan.net/
 
 Pierre-Yves Vandenbussche.
 
 Andrea Splendiani
 Senior Bioinformatics Scientist
 Centre for Mathematical and Computational Biology
 +44(0)1582 763133 ext 2004
 andrea.splendi...@bbsrc.ac.uk
 
 
 
 
 -- 
 Hugh Glaser,  
 Intelligence, Agents, Multimedia
 School of Electronics and Computer Science,
 University of Southampton,
 Southampton SO17 1BJ
 Work: +44 23 8059 3670, Fax: +44 23 8059 3045
 Mobile: +44 78 9422 3822, Home: +44 23 8061 5652
 http://www.ecs.soton.ac.uk/~hg/
 
 
 
 Andrea Splendiani
 Senior Bioinformatics Scientist
 Centre for Mathematical and Computational Biology
 +44(0)1582 763133 ext 2004
 andrea.splendi...@bbsrc.ac.uk
 
 
 

-- 
Hugh Glaser,  
  Intelligence, Agents, Multimedia
  School of Electronics and Computer Science,
  University of Southampton,
  Southampton SO17 1BJ
Work: +44 23 8059 3670, Fax: +44 23 8059 3045
Mobile: +44 78 9422 3822, Home: +44 23 8061 5652
http://www.ecs.soton.ac.uk/~hg/





Re: The truth about SPARQL Endpoint availability

2011-03-05 Thread Michael Hausenblas


I'm no SPARQL or voiD guru, but I think you need a bit more wrapping  
in the scovo stuff, so more like:

ROTFL, reading that Hugh claims to be *not* a VoID guru ;)
Note that SCOVO modelling of stats in VoID has been deprecated and  
simplified [1].



Fancy the challenge, it is the weekend?! :-)


Indeed!

Cheers,
Michael
[1] http://www.w3.org/TR/void/#statistics
--
Dr. Michael Hausenblas, Research Fellow
LiDRC - Linked Data Research Centre
DERI - Digital Enterprise Research Institute
NUIG - National University of Ireland, Galway
Ireland, Europe
Tel. +353 91 495730
http://linkeddata.deri.ie/
http://sw-app.org/about.html

On 5 Mar 2011, at 15:14, Hugh Glaser wrote:


Hi,
On 5 Mar 2011, at 14:22, Andrea Splendiani wrote:


Hi,

I think it depends on the store, I've tried some (from the endpoint  
list) and some returns a answer pretty quickly. Some doesn't and  
some doesn't support count.
However, one could have this information only for the stores that  
answers the count query, no need to try all time.
I am happy for a store implementor or owner to disagree, but I find  
it very unlikely that the owner of a store with a decent chunk of  
data ( 1M triples, say) would be happy for someone to keep issuing  
such a query, even if they did decide to give enough resources to  
execute it.

I would quickly blacklist such a site.


VoID:
is this a good query:
select * where {?s http://rdfs.org/ns/void#numberOfTriples ?o }


I'm no SPARQL or voiD guru, but I think you need a bit more wrapping  
in the scovo stuff, so more like:


SELECT DISTINCT ?endpoint ?uri ?triples ?uris WHERE
  { ?ds a void:Dataset .
?ds void:sparqlEndpoint ?uri .
?ds rdfs:label ?endpoint .
?ds void:statItem [ scovo:dimension  
void:numberOfTriples ; rdf:value  ?triples ] .

 }

Try it at
http://kwijibo.talis.com/voiD/
or
http://void.rkbexplorer.com/

I guess Pierre-Yves might like to enhance his page by querying a  
voiD store to also give basic stats.
Or someone might like to do a store reporter that uses (a) voiD  
endpoint(s) plus Pierre-Yves's data (he has a SPARQL endpoint), to  
do so.

And maybe the CKAN endpoint would have extra useful data as well.
A real Semantic Web application that queried more than one SPARQL  
endpoint - now that would be a novelty!

Fancy the challenge, it is the weekend?! :-)

ciao
Hugh



it doesn't seem viable if so.

ciao,
Andrea


Il giorno 05/mar/2011, alle ore 13.49, Hugh Glaser ha scritto:


NIce idea, but,... :-)

SELECT (count(*) as ?c) WHERE {?s ?p ?o}

is a pretty anti-social thing to do to a store.
At best, a store of any size will spend a while thinking, and then  
quite rightly decide they have burnt enough resources, and return  
some sort of error.


For a properly maintained site, of course, the VoiD description  
will give lots of similar information.

Best
Hugh

On 5 Mar 2011, at 13:06, Andrea Splendiani wrote:


Hi, very nice!
I have a small suggestion:

why don't you ask count(*) where {?s ?p ?o} to the endpoint ?
Or ask for the number of graphs ?
Both information, number of triples and number of graphs, if  
logged and compared over time, can give a practical view of the  
liveliness of the content of the endpoint.


best,
Andrea Splendiani


Il giorno 28/feb/2011, alle ore 18.55, Pierre-Yves Vandenbussche  
ha scritto:



Hello all,

you have already encountered problems of SPARQL endpoint  
accessibility ?

you feel frustrated they are never available when you need them?
you develop an application using these services but wonder if it  
is reliable?


Here is a tool [1] that allows you to know public SPARQL  
endpoints availability and monitor them in the last hours/days.
Stay informed of a particular (or all) endpoint status changes  
through RSS feeds.
All availability information generated by this tool is  
accessible through a SPARQL endpoint.


This tool fetches public SPARQL endpoints from CKAN  open data.  
From this list, it runs tests every hour for availability.


[1] http://labs.mondeca.com/sparqlEndpointsStatus/index.html
[2] http://ckan.net/

Pierre-Yves Vandenbussche.


Andrea Splendiani
Senior Bioinformatics Scientist
Centre for Mathematical and Computational Biology
+44(0)1582 763133 ext 2004
andrea.splendi...@bbsrc.ac.uk





--
Hugh Glaser,
   Intelligence, Agents, Multimedia
   School of Electronics and Computer Science,
   University of Southampton,
   Southampton SO17 1BJ
Work: +44 23 8059 3670, Fax: +44 23 8059 3045
Mobile: +44 78 9422 3822, Home: +44 23 8061 5652
http://www.ecs.soton.ac.uk/~hg/




Andrea Splendiani
Senior Bioinformatics Scientist
Centre for Mathematical and Computational Biology
+44(0)1582 763133 ext 2004
andrea.splendi...@bbsrc.ac.uk





--
Hugh Glaser,
 Intelligence, Agents, Multimedia
 School of Electronics and Computer Science,
 University of Southampton,
 Southampton SO17 1BJ
Work: +44 23 8059 

Re: The truth about SPARQL Endpoint availability

2011-03-05 Thread Hugh Glaser

On 5 Mar 2011, at 15:23, Michael Hausenblas wrote:

 
 I'm no SPARQL or voiD guru, but I think you need a bit more wrapping in the 
 scovo stuff, so more like:
 ROTFL, reading that Hugh claims to be *not* a VoID guru ;)
Tee hee.
Very kind, but
 Note that SCOVO modelling of stats in VoID has been deprecated and simplified 
 [1].

sort of proves my assertion :-)
And perhaps this little interchange proves the assertion in [1]
Statistics would be verbose, and querying them with SPARQL was difficult.

I was looking at our voiD docs.
Seems we have not updated them, and they still do scovo.
Better make sure the boys get to work :-)
 
 Fancy the challenge, it is the weekend?! :-)
 
 Indeed!
Cheers
 
 Cheers,
   Michael
 [1] http://www.w3.org/TR/void/#statistics
 --
 Dr. Michael Hausenblas, Research Fellow
 LiDRC - Linked Data Research Centre
 DERI - Digital Enterprise Research Institute
 NUIG - National University of Ireland, Galway
 Ireland, Europe
 Tel. +353 91 495730
 http://linkeddata.deri.ie/
 http://sw-app.org/about.html
 
 On 5 Mar 2011, at 15:14, Hugh Glaser wrote:
 
 Hi,
 On 5 Mar 2011, at 14:22, Andrea Splendiani wrote:
 
 Hi,
 
 I think it depends on the store, I've tried some (from the endpoint list) 
 and some returns a answer pretty quickly. Some doesn't and some doesn't 
 support count.
 However, one could have this information only for the stores that answers 
 the count query, no need to try all time.
 I am happy for a store implementor or owner to disagree, but I find it very 
 unlikely that the owner of a store with a decent chunk of data ( 1M 
 triples, say) would be happy for someone to keep issuing such a query, even 
 if they did decide to give enough resources to execute it.
 I would quickly blacklist such a site.
 
 VoID:
 is this a good query:
 select * where {?s http://rdfs.org/ns/void#numberOfTriples ?o }
 
 I'm no SPARQL or voiD guru, but I think you need a bit more wrapping in the 
 scovo stuff, so more like:
 
 SELECT DISTINCT ?endpoint ?uri ?triples ?uris WHERE
  { ?ds a void:Dataset .
?ds void:sparqlEndpoint ?uri .
?ds rdfs:label ?endpoint .
?ds void:statItem [ scovo:dimension void:numberOfTriples ; 
 rdf:value  ?triples ] .
 }
 
 Try it at
 http://kwijibo.talis.com/voiD/
 or
 http://void.rkbexplorer.com/
 
 I guess Pierre-Yves might like to enhance his page by querying a voiD store 
 to also give basic stats.
 Or someone might like to do a store reporter that uses (a) voiD endpoint(s) 
 plus Pierre-Yves's data (he has a SPARQL endpoint), to do so.
 And maybe the CKAN endpoint would have extra useful data as well.
 A real Semantic Web application that queried more than one SPARQL endpoint - 
 now that would be a novelty!
 Fancy the challenge, it is the weekend?! :-)
 
 ciao
 Hugh
 
 
 it doesn't seem viable if so.
 
 ciao,
 Andrea
 
 
 Il giorno 05/mar/2011, alle ore 13.49, Hugh Glaser ha scritto:
 
 NIce idea, but,... :-)
 
 SELECT (count(*) as ?c) WHERE {?s ?p ?o}
 
 is a pretty anti-social thing to do to a store.
 At best, a store of any size will spend a while thinking, and then quite 
 rightly decide they have burnt enough resources, and return some sort of 
 error.
 
 For a properly maintained site, of course, the VoiD description will give 
 lots of similar information.
 Best
 Hugh
 
 On 5 Mar 2011, at 13:06, Andrea Splendiani wrote:
 
 Hi, very nice!
 I have a small suggestion:
 
 why don't you ask count(*) where {?s ?p ?o} to the endpoint ?
 Or ask for the number of graphs ?
 Both information, number of triples and number of graphs, if logged and 
 compared over time, can give a practical view of the liveliness of the 
 content of the endpoint.
 
 best,
 Andrea Splendiani
 
 
 Il giorno 28/feb/2011, alle ore 18.55, Pierre-Yves Vandenbussche ha 
 scritto:
 
 Hello all,
 
 you have already encountered problems of SPARQL endpoint accessibility ?
 you feel frustrated they are never available when you need them?
 you develop an application using these services but wonder if it is 
 reliable?
 
 Here is a tool [1] that allows you to know public SPARQL endpoints 
 availability and monitor them in the last hours/days.
 Stay informed of a particular (or all) endpoint status changes through 
 RSS feeds.
 All availability information generated by this tool is accessible 
 through a SPARQL endpoint.
 
 This tool fetches public SPARQL endpoints from CKAN  open data. From 
 this list, it runs tests every hour for availability.
 
 [1] http://labs.mondeca.com/sparqlEndpointsStatus/index.html
 [2] http://ckan.net/
 
 Pierre-Yves Vandenbussche.
 
 Andrea Splendiani
 Senior Bioinformatics Scientist
 Centre for Mathematical and Computational Biology
 +44(0)1582 763133 ext 2004
 andrea.splendi...@bbsrc.ac.uk
 
 
 
 
 -- 
 Hugh Glaser,
   Intelligence, Agents, Multimedia
   School of Electronics and Computer Science,
   University of Southampton,
   Southampton SO17 1BJ
 Work: +44 23 8059 3670, Fax: +44 23 

Re: The truth about SPARQL Endpoint availability

2011-03-05 Thread Bill Roberts
Thanks Hugh - as someone running a couple of SPARQL endpoints, I'd certainly 
prefer if people don't run a global count too often (or at all). It is indeed 
something that makes typical SPARQL implementations work very hard.

But it's a good reminder we should provide an alternative and i'll look into 
providing triple counts in voiD.

Bill


On 5 Mar 2011, at 15:14, Hugh Glaser wrote:

 Hi,
 On 5 Mar 2011, at 14:22, Andrea Splendiani wrote:
 
 Hi,
 
 I think it depends on the store, I've tried some (from the endpoint list) 
 and some returns a answer pretty quickly. Some doesn't and some doesn't 
 support count.
 However, one could have this information only for the stores that answers 
 the count query, no need to try all time.
 I am happy for a store implementor or owner to disagree, but I find it very 
 unlikely that the owner of a store with a decent chunk of data ( 1M triples, 
 say) would be happy for someone to keep issuing such a query, even if they 
 did decide to give enough resources to execute it.
 I would quickly blacklist such a site.
 
 VoID:
 is this a good query:
 select * where {?s http://rdfs.org/ns/void#numberOfTriples ?o } 
 
 I'm no SPARQL or voiD guru, but I think you need a bit more wrapping in the 
 scovo stuff, so more like:
 
 SELECT DISTINCT ?endpoint ?uri ?triples ?uris WHERE
   { ?ds a void:Dataset .
 ?ds void:sparqlEndpoint ?uri .
 ?ds rdfs:label ?endpoint .
 ?ds void:statItem [ scovo:dimension void:numberOfTriples ; 
 rdf:value  ?triples ] .
  }
 
 Try it at
 http://kwijibo.talis.com/voiD/
 or
 http://void.rkbexplorer.com/
 
 I guess Pierre-Yves might like to enhance his page by querying a voiD store 
 to also give basic stats.
 Or someone might like to do a store reporter that uses (a) voiD endpoint(s) 
 plus Pierre-Yves's data (he has a SPARQL endpoint), to do so.
 And maybe the CKAN endpoint would have extra useful data as well.
 A real Semantic Web application that queried more than one SPARQL endpoint - 
 now that would be a novelty!
 Fancy the challenge, it is the weekend?! :-)
 
 ciao
 Hugh
 
 
 it doesn't seem viable if so.
 
 ciao,
 Andrea
 
 
 Il giorno 05/mar/2011, alle ore 13.49, Hugh Glaser ha scritto:
 
 NIce idea, but,... :-)
 
 SELECT (count(*) as ?c) WHERE {?s ?p ?o}
 
 is a pretty anti-social thing to do to a store.
 At best, a store of any size will spend a while thinking, and then quite 
 rightly decide they have burnt enough resources, and return some sort of 
 error.
 
 For a properly maintained site, of course, the VoiD description will give 
 lots of similar information.
 Best
 Hugh
 
 On 5 Mar 2011, at 13:06, Andrea Splendiani wrote:
 
 Hi, very nice!
 I have a small suggestion:
 
 why don't you ask count(*) where {?s ?p ?o} to the endpoint ?
 Or ask for the number of graphs ?
 Both information, number of triples and number of graphs, if logged and 
 compared over time, can give a practical view of the liveliness of the 
 content of the endpoint.
 
 best,
 Andrea Splendiani
 
 
 Il giorno 28/feb/2011, alle ore 18.55, Pierre-Yves Vandenbussche ha 
 scritto:
 
 Hello all,
 
 you have already encountered problems of SPARQL endpoint accessibility ?
 you feel frustrated they are never available when you need them?
 you develop an application using these services but wonder if it is 
 reliable?
 
 Here is a tool [1] that allows you to know public SPARQL endpoints 
 availability and monitor them in the last hours/days. 
 Stay informed of a particular (or all) endpoint status changes through 
 RSS feeds.
 All availability information generated by this tool is accessible through 
 a SPARQL endpoint.
 
 This tool fetches public SPARQL endpoints from CKAN  open data. From this 
 list, it runs tests every hour for availability.
 
 [1] http://labs.mondeca.com/sparqlEndpointsStatus/index.html
 [2] http://ckan.net/
 
 Pierre-Yves Vandenbussche.
 
 Andrea Splendiani
 Senior Bioinformatics Scientist
 Centre for Mathematical and Computational Biology
 +44(0)1582 763133 ext 2004
 andrea.splendi...@bbsrc.ac.uk
 
 
 
 
 -- 
 Hugh Glaser,  
Intelligence, Agents, Multimedia
School of Electronics and Computer Science,
University of Southampton,
Southampton SO17 1BJ
 Work: +44 23 8059 3670, Fax: +44 23 8059 3045
 Mobile: +44 78 9422 3822, Home: +44 23 8061 5652
 http://www.ecs.soton.ac.uk/~hg/
 
 
 
 Andrea Splendiani
 Senior Bioinformatics Scientist
 Centre for Mathematical and Computational Biology
 +44(0)1582 763133 ext 2004
 andrea.splendi...@bbsrc.ac.uk
 
 
 
 
 -- 
 Hugh Glaser,  
  Intelligence, Agents, Multimedia
  School of Electronics and Computer Science,
  University of Southampton,
  Southampton SO17 1BJ
 Work: +44 23 8059 3670, Fax: +44 23 8059 3045
 Mobile: +44 78 9422 3822, Home: +44 23 8061 5652
 http://www.ecs.soton.ac.uk/~hg/