SPARQL queries with functions "contains" and "regex" don't work

[Christian Schwaderer]

Hi there!

I've encountered a strange behaviour of ARC2.

I run a fuseki server and want to run sparql queries from a PHP application. I start the query the way the documentation demonstrates:

include_once("arc2/ARC2.php");
 $config = array(
'remote_store_endpoint' => 'http://localhost:3030/my_dataset/query',
);
$store = ARC2::getRemoteStore($config);
$results_as_array = $store->query($query_string, 'rows');

So far, everything is alright. The problem starts when I use the SPARQL functions "contains" or "rand". For example this simple query:

PREFIX rdfs:  <http://www.w3.org/2000/01/rdf-schema#>

SELECT ?name

WHERE
{
 ?s rdfs:label ?name .
 FILTER (contains(?name,"Richard"))
}

It doesn't work at all.

var_dump($results_as_array);

only results in "array(0) { } ".

The very same query works in the Fuseki webinterface and with the PHP libraries Easy RDF and RAP (RDF API for PHP).

It works again with ARC, as soon as I remove "contains" or replace it with "regex" or something else.

So, I'm quite sure this is a bug in ARC2.

[Ryfa]

Hi,

Contains is a primitive of sparql 1.1 and arc doesn't implemented it.

[Christian Schwaderer]

Just as an addition: As I said, the query with "contains" works with RAP (RDF API for PHP). I use version 0.9.6 which dates back from 2008-02-29, while SPARQL 1.1 became a W3C recommendation in March 2013. That means at least, that the SPARQL 1.1 elements do not necessarily cause problems if they are not supported by the API.

[Christian Schwaderer]

Thanks for the information.

But why are SPARQL 1.1 functions a problem here?
Maybe, I don't understand, what arc does. I thought, arc works just as a wrapper here and Fuseki (resp. ARQ) interprets the SPARQL query. So, I assumed, it doesn't matter whether arc has implemented SPARQL 1.1 or not.