good evening, martynas;
On 29 Sep 2013, at 2:03 PM, Martynas Jusevičius wrote: > Hey, > > I want to do federation between to endpoints, both of which contain > named graphs. I'm trying a query of this shape: > > [...] this is one of the several aspects of federation semantics which the recommendations leave incomplete. the respective descriptions of algebra translations and semantics, below, suggest that the initial dataset for the remote query is the remote service's default dataset and that, in particular, the dataset restriction effected by a graph operation, via eval(D(D[IRI]), P) has no bearing on the interpretation of the service form, Invocation(IRI, P, SilentOp) in which, as the 'P' expression includes no provision to specify any dataset, it is necessarily applied to whatever dataset the remote service provides when a query does not describe the dataset. in the context of your use case, this which would mean that the first statement pattern would be executed against the default graph of that default dataset and the inner graph clause would restrict that dataset with its graph for its contained patterns. best regards, from berlin, ---- http://www.w3.org/TR/2013/REC-sparql11-query-20130321/#sparqlTranslateGraphPatterns http://www.w3.org/TR/2013/REC-sparql11-query-20130321/#defn_evalGraph http://www.w3.org/TR/2013/REC-sparql11-federated-query-20130321/#defn_service --- james anderson | [email protected] | http://dydra.com
