Thank you for your reply. I am working towards an extension of sparql which would make possible to make "nice looking" OLAP queries over RDF data. When I first noticed property functions, they seem to be a nice way to do it. Unfortunately Jena TDB seem to be performing quite poorly in comparison to e.g. Virtuoso, which lead me to look at a combination of Jena and Virtuoso.
The OLAP extension does not have to be through property functions, it may be more viable to do through regular functions (in a FILTER clause). Is it possible to define such in Virtuoso? If so, I may simply discard Jena and use only Virtuoso. I should probably notice that this is work for my master thesis at Aalborg University. 2014-03-09 23:39 GMT+01:00 Hugh Williams <hwilli...@openlinksw.com>: > Hi Alex, > > To use these Jena specific functions they would need to be implemented in the > Jena provider or Virtuoso Server. But as Andy Seaboure indicates in you > stackoverflow post, "The apf:str functionality is better done nowadays as > FILTER or BIND and STR()" , thus would this suffice for your use case ? > > Best Regards > Hugh Williams > Professional Services > OpenLink Software, Inc. // http://www.openlinksw.com/ > Weblog -- http://www.openlinksw.com/blogs/ > LinkedIn -- http://www.linkedin.com/company/openlink-software/ > Twitter -- http://twitter.com/OpenLink > Google+ -- http://plus.google.com/100570109519069333827/ > Facebook -- http://www.facebook.com/OpenLinkSoftware > Universal Data Access, Integration, and Management Technology Providers > > On 6 Mar 2014, at 15:55, Alex Bondo Andersen <abon...@gmail.com> wrote: > >> Hi everyone, >> >> This question is related to virt-jena, but it is my understanding that >> it is also developed by Virtuoso, hence directing the question to you >> guys. >> >> I also posted the question on stackoverflow: >> http://stackoverflow.com/questions/22229302/property-functions-in-virtuoso >> >> I am planning to have Jena as the interface and Virtuoso as the >> backend storage, since Jena seems to be easier to extend and Virtuoso >> have some nice features such as conversion of relational data into >> RDF. My problem is that the property functions that are in Jena, and >> the ones that I want to implement, does not seem to have any effect >> when virtuoso is used as the underlying storage. >> >> Example of query working when using TDB (TDBFactory.createDataset) to >> make a dataset but not working when using Virtuoso (VirtGraph, >> VirtDataset, and also tried QueryExecutionFactory.sparqlService): >> >> PREFIX apf: <java:com.hp.hpl.jena.sparql.pfunction.library.> >> SELECT * >> WHERE >> { ?s apf:str "Test" } >> LIMIT 5 >> >> I am looking for a way to make Jena/ARQ pre- or post process the >> results of a query sent to Virtuoso. >> >> If that is not possible, please point in alternative directions. >> Implementing property function in Virtuoso or use Sesame or other >> easily extendable system instead are my own initial thoughts. >> >> >> -- >> Med venlig hilsen / Best Regards >> Alex Bondo Andersen >> >> ------------------------------------------------------------------------------ >> Subversion Kills Productivity. Get off Subversion & Make the Move to >> Perforce. >> With Perforce, you get hassle-free workflows. Merge that actually works. >> Faster operations. Version large binaries. Built-in WAN optimization and the >> freedom to use Git, Perforce or both. Make the move to Perforce. >> http://pubads.g.doubleclick.net/gampad/clk?id=122218951&iu=/4140/ostg.clktrk >> _______________________________________________ >> Virtuoso-users mailing list >> Virtuoso-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/virtuoso-users > -- Med venlig hilsen / Best Regards Alex Bondo Andersen ------------------------------------------------------------------------------ Learn Graph Databases - Download FREE O'Reilly Book "Graph Databases" is the definitive new guide to graph databases and their applications. Written by three acclaimed leaders in the field, this first edition is now available. Download your free book today! http://p.sf.net/sfu/13534_NeoTech _______________________________________________ Virtuoso-users mailing list Virtuoso-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/virtuoso-users
