Enabled federated queries on my local stand-alone, but bindings don't 'take' - Wikidata-tech

11 Apr 2016

I posted this last week to wikidata(a)lists.wikimedia.org, but perhaps 
this is a better forum for this problem. Re-posting it here.

Federated queries are disabled on the stand-alone code out-of-the-box.

I followed the advice on this post to un-disable federated queries for 
my local installation: 
https://lists.wikimedia.org/pipermail/wikidata/2016-March/008444.html

(Thanks Mr. Malyshev!)

I did have one problem with the build: I found myself having to remove 
the checkstyle plugin from the pom.xml file to get the maven build to go 
to completion.

Now on my local installation I can get this query to work just fine:

(Current namespace: wdq)
Select *
Where
{
   Service <http://localhost:9999/bigdata/namespace/test/sparql>
   {
     Bind ("Algeria"@en as ?countryLabel)
   }
}

Also this:

(current namespace: test)
prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>
Select *
Where
{
   Service <http://localhost:9999/bigdata/namespace/wdq/sparql>
   {
     Bind ("Algeria"@en as ?countryLabel)
     ?country rdfs:label ?countryLabel.
   }
}

But this query (and every variation I could think of) unfortunately 
times out:
(current namespace: wdq)
prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>
Select *
Where
{
   {
     Select ?countryLabel
     {
       Service <http://localhost:9999/bigdata/namespace/test/sparql>
       {
         Bind ("Algeria"@en as ?countryLabel)
       }
     }
   }
   ?country rdfs:label ?countryLabel.
}

This is also the case when addressing a Jena service I have set up on a 
different port.

I would appreciate any guidance you could give me.

Thanks and regards,