I just re-read your message more carefully and realized that you are using a version of Jena <3. In this case, I believe you will want to use, instead of the type Function<>, the older type Map1<> if you want to use my suggestion. I am sorry for any confusion.
--- A. Soroka The University of Virginia Library > On Oct 15, 2015, at 12:00 PM, Enrico Daga (enridaga) <[email protected]> > wrote: > > Thank you for your reply. > Actually the problem is not really about the representation - for example I > might use the DataCube vocabulary - but is more about how to use the Jena > serialisers to stream custom triples adapted from a ResultSet efficiently. > The ResultSetFormatter.toModel approach is not the one I like, as it requires > the RDF to be generated in memory before serialisation. > I posted my solution to SO: > http://stackoverflow.com/questions/33136916/streaming-a-resultset-as-rdf-using-a-custom-vocabulary/33153024#33153024 > > <http://stackoverflow.com/questions/33136916/streaming-a-resultset-as-rdf-using-a-custom-vocabulary/33153024#33153024> > (Are there better ways of doing that?) > > However, it looks like the streaming features do not support all RDF syntax, > as I got a RIOT exception when I ask for RDF/XML or RDF/JSON formats. > So now my problem is how to support all serialisations. > Or maybe my version of Jena is outdated (2.12.1) and I should use Jena 3? > > Thanks, > > Enrico > > >> On 14 Oct 2015, at 18:53, A. Soroka <[email protected]> wrote: >> >> Perhaps you could say more about the representation you want to use? >> ResultSetFormatter does feature methods that (to my understanding) do stream >> using Jena serialization: >> >> https://jena.apache.org/documentation/javadoc/arq/org/apache/jena/query/ResultSetFormatter.html#output-java.io.OutputStream-org.apache.jena.query.ResultSet-org.apache.jena.sparql.resultset.ResultsFormat- >> >> <https://jena.apache.org/documentation/javadoc/arq/org/apache/jena/query/ResultSetFormatter.html#output-java.io.OutputStream-org.apache.jena.query.ResultSet-org.apache.jena.sparql.resultset.ResultsFormat-> >> >> --- >> A. Soroka >> The University of Virginia Library >> >>> On Oct 14, 2015, at 6:39 PM, Enrico Daga (enridaga) <[email protected] >>> <mailto:[email protected]>> wrote: >>> >>> Hi, >>> >>> in my use case I need to stream a ResultSet obtained from a query to a >>> remote endpoint converted into an RDF output format. >>> I know Jena provides a ResultSetFormatter.toModel facility for that, >>> however I have the following constraints: >>> - I want to use a different representation/vocabulary and not the one >>> provided by Jena, and >>> - I don't want to load the data in memory. In other words I don't want to >>> create a Model and fill it with the ResultSet, but streaming out the >>> triples while I iterate on it, to control memory consumption. >>> - I still want to benefit by the Jena serializers >>> >>> I have seen the StreamRDF interface, but I am not very clear about how to >>> use it effectively. >>> What could be a correct approach in this scenario? >>> >>> Thank you, >>> >>> Enrico >>> >>> — >>> Enrico Daga (enridaga) >>> http://www.enridaga.net <http://www.enridaga.net/> >>> <http://www.enridaga.net/ <http://www.enridaga.net/>> >>> Il budda e’ nel parco. >
