RE: Discovering a query endpoint associated with a given Linked Data resource

There is the SPARQL Service Description vocabulary.

http://www.w3.org/TR/sparql11-service-description/


From: Nandana Mihindukulasooriya [mailto:nmihindu@fi.upm.es]
Sent: Wednesday, 26 August 2015 6:46 PM
To: public-lod <public-lod@w3.org>
Subject: Discovering a query endpoint associated with a given Linked Data resource

Hi,

Is there a standard or widely used way of discovering a query endpoint (SPARQL/LDF) associated with a given Linked Data resource?

I know that a client can use the "follow your nose" and related link traversal approaches such as [1], but if I wonder if it is possible to have a hybrid approach in which the dereferenceable Linked Data resources that optionally advertise query endpoint(s) in a standard way so that the clients can perform queries on related data.

To clarify the use case a bit, when a client dereferences a resource URI it gets a set of triples (an RDF graph) [2].  In some cases, it might be possible that the returned graph could be a subgraph of a named graph / default graph of an RDF dataset. The client wants to discover if a query endpoint that exposes the relevant dataset, if one is available.

For example, something like the following using the "search" link relation [3].

------
HEAD /resource/Sri_Lanka
Host: http://dbpedia.org
------
200 OK
Link: <http://dbpedia.org/sparql>; rel="search"; type="sparql", <http://fragments.dbpedia.org/2014/en#dataset>; rel="search"; type="ldf"
... other headers ...
------

Best Regards,
Nandana

[1] http://swsa.semanticweb.org/sites/g/files/g524521/f/201507/DissertationOlafHartig_0.pdf

[2] http://www.w3.org/TR/2014/REC-rdf11-concepts-20140225/#section-rdf-graph

[3] http://www.iana.org/assignments/link-relations/link-relations.xhtml