Clerezza Yard setup and SPARQL

[Rajan Shah]

Hi,

In order to use Clerezza Yard setup, I tried very simple example outlined
at the end.

I would really appreciate, if someone can shed some light on

a. Is there anything I am just completely missing here pertaining to "Named
Graph" vs "Unions of Graphs" and reference? If that's the case, could you
please clarify what would be relevant URI/IRI?

b. What is the best way to debug such an issue? If SPARQL query fails,
where should I see the logs indicating any issue as it doesn't appear in
stdout logs?

c. Is there any other simple alternative compare to this to achieve similar
functionality? Is storing in Kiwi beneficial compared to this approach or
do I have to have Apache Maramotta installed in order to use Kiwi?

Thanks in advance,
Rajan


*1. Apache Stanbol Entityhub Yard: Clerezza Yard Configuration*

Set following parameters

ID: testYard
Graph URI: http://test.io/ns/friends#

*2. Setup Clerezza - SCB Jena TDB Storage Provider*

Jena TDB directory: /<stanbol_dir>/<tdb_store>
Default Graph Name: http://test.io/ns
Weight: 105

*3. Save the .ttl file into /<stanbol_dir>/<tdb_store>*

@prefix vcard: <http://www.w3.org/2006/vcard/ns#> .
@prefix rdfa: <http://www.w3.org/ns/rdfa#> .
@prefix friends: <http://test.io/ns/friends#> .

<http://test.io/ns/friends#AndrewSmith> a vcard:Individual;
                    vcard:fn "Andrew Smith";
                    vcard:title "Founder";
                    vcard:org "ABC LLC";
                    vcard:orgunit "Startup";
                    vcard:hasAddress [
                                        a vcard:Work;
                                        vcard:country-name "USA";
                                        vcard:locality "New York";
                                        vcard:region "New York"
                    ] .

*4. I do see that, upon startup, it creates necessary index files within *
/<stanbol_dir>/<tdb_store>
directory. In addition, within UI, it also registers following
TripleCollections in SPARQL Endpoint

http://test.io/ns/friends#

*5. SPARQL Query*
-- query1
PREFIX vcard: <http://www.w3.org/2006/vcard/ns#>
PREFIX friends: <http://test.io/ns/friends#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>

SELECT ?fn ?title ?org
WHERE {
  ?s vcard:fn ?fn ;
    vcard:title ?title ;
    vcard:org ?org .
}

OR

-- query2
PREFIX hmgr: <http://test.io/ns/friends#>
PREFIX vcard: <http://www.w3.org/2006/vcard/ns#>

SELECT ?Individual ?title
WHERE { ?title  vcard:title  "Founder" }


*Observations:*

The above queries work perfectly fine on either command-line or Jena Fuseki
as follows

a. tdbquery --loc /<stanbol_dir/<tdb_store> --query query1
b. using fuseki user interface

I tried couple alternatives such as GRAPH, NAMED, etc... however nothing
helps. Is there any specific syntax need to be used for the SPARQL stanbol
interface?