In the Linked Data world, how can i chain together two SPARQL queries to different SPARQL endpoints, such that the second one uses results from the first one as part of the query.

For example, @pezholio's example at http://www.pezholio.co.uk/2010/07/further-adventures-in-sparql/ suggests it might be possible to run a SPARQL query on the Ordnance Survey endpoint to return a district ward that a particular postcode is in, and a separate query on the National Statistics endpoint to find the Parliamentary constituency that the ward is in. That is, you can go from postcode to ward via OS, and ward to constituency via NS; but i want a single query to go from postcode to constituency via OS and NS...

Is it possible to write a single sparql query that somehow combines these two things and asks a compound query over the two endpoints?

asked 11 Dec '10, 19:45

psychemedia's gravatar image

psychemedia ♦♦
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edited 11 Dec '10, 19:47


You could download Jena and try the new SERVICE keyword http://jena.sourceforge.net/ARQ/service.html

Currently it is more common to put all the data you need in one store to query it.

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This answer is marked "community wiki".

answered 14 Jan '11, 23:46

keithalexander's gravatar image

keithalexander
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Is this available on the Talis platform?

(15 Jan '11, 09:19) kitwallace
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The SERVICE keyword is a SPARQL 1.1 keyword, so any endpoint that is SPARQL 1.1 conform can do that. Have a look at w3c working draft http://www.w3.org/TR/sparql11-federated-query/ . Talis seems to work on SPARQL1.1 at least since February 2011 so I would assume you can use SERVICE, give it a try :) https://talisplatform.zendesk.com/entries/439752-support-sparql-1-1

(30 Apr, 09:33) dr0i
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Asked: 11 Dec '10, 19:45

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Last updated: 10 May, 09:24

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