Andy, Could you give an Java code illustrative example for the second case where ARQ.enableBlankNodeResultLabels(true) ; is used in Java code to configure SPARQL engine? I'm probably missing something here and believe the example may help. I assume the method is static configuration method and if used in any stage of init chain it should work (or any other moment before the SPARQL query is executed). Unfortunately, it has no effect in my case.
Thanks, Milorad >________________________________ > From: Andy Seaborne <[email protected]> >To: [email protected] >Sent: Monday, July 9, 2012 3:46 PM >Subject: Re: blank nodes in ARQ > >On 09/07/12 13:45, Milorad Tosic wrote: >> >> >> Hi, >> >> I am aware of some earlier discussions on the list about blank nodes as well >> as discussions on other places (e.g. [1]). So, my intention here is not to >> launch a general purpose theoretic discussion here. Instead, I would focus >> on the following question: >> >> In the paper [2], authors say: "For example, ARQ is a commonly (re)used >> SPARQL processor which supports a non-standard <_:b1> style syntax for terms >> in queries, indicating that the term can only be bound by a blank node >> labeled “b1” in the data." However, a simple query like the following >> >> >> SELECT DISTINCT ?pp ?oo >> WHERE { >> <_:b1> ?pp ?oo . > >This must the internal identifier,and "b1" is not that. > >You need to get the real internal identifier: > >1/ At the API, it's the AnonId from Resource.getId(); >2/ To get the protocol engine to expose internal identifiers, ensure the >server is running with these context settings > >Call >ARQ.enableBlankNodeResultLabels(true) ; > >The TSV format output outputs (encoded) bnodes internal identifiers anyway. > >> } >> >> gives an empty result set even though query >> >> SELECT DISTINCT ?s ?pp ?oo >> WHERE { >> ?s ?pp ?oo . >> FILTER (isBlank(?s)) >> } >> >> gives result set where _:b1 appears several times. > >Irrelevent :-) > >That "_:b1" is, I guess, the result-file-scoped translation, Normally >internal identifiers aren't exposed. > >> >> So, the question is whether I am using wrong syntax or something has changed >> in ARQ or else? > >What's your setup? How are you making the query? > >> >> Thanks, >> >> Milorad >> >> >> [1] http://www.w3.org/wiki/BnodeSkolemization >> [2] web.ing.puc.cl/~marenas/publications/iswc11.pdf >> > > > > >
