Search code examples
jenaarq

Jena UpdateFactory

I was wondering if it was possible to create a SPARQL UpdateRequest in Jena by using ARQ Op objects. I would be interested to create programmatically updates like this:

DELETE {?s :predicate <http://example.org#old> }    
INSERT {?s :predicate <http://example.org#toAdd>} 
WHERE  {?s :predicate <http://example.org#old> }

by creating the patterns in the DELETE, INSERT, and WHERE clauses from the ARQ API. So far the only ways I have found to create SPARQL Update requests require to parse a SPARQL string or to create a com.hp.hpl.jena.update.Update object (which uses QuadAcc objects for which I couldn't find examples of use.

My fear is that the management of SPARQL UPDATE requests and the one of SPARQL SELECT queries are separated and that ARQ cannot be used to 'assemble' queries on the fly.

Thanks in advance

Solution

  • I haven't tried this myself, but it looks like creating Update objects and assembling them into an UpdateRequest is indeed the way to go.

    After a short look, QuadAcc doesn't seem particularly difficult, just use addTriple() with triples that contain variables.

    The UpdateModify subclass of Update looks particularly interesting, it corresponds to the DELETE … INSERT … WHERE pattern in your example. Unfortunately the WHERE clause is initialised with an Element (syntactic representation of a query part) rather than an Op (algebraic representation).