KDBQueries

kDBQueries is a kDB extension which allows to generate API to execute queries in kDB and return them as high-level structures.

Queries Description

@prefix dc: <http://purl.org/dc/elements/1.1/> .
@prefix foaf: <http://xmlns.com/foaf/0.1/> .
@prefix askcore_queries: <http://askco.re/queries#> .
@prefix askcore_graphs: <http://askco.re/graphs#> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
@prefix xsi: <http://www.w3.org/2001/XMLSchema-instance#> .
@prefix geo: <http://www.opengis.net/ont/geosparql#> .
 
 
<salient_object_insert> dc:description "Insert a salient object in a graph" ;
                 foaf:name "salient_object_insert" ;
                 askcore_queries:query """PREFIX example: <http://example.org/>
PREFIX w3cGeo: <http://www.w3.org/2003/01/geo/wgs84_pos#>
 
INSERT DATA { GRAPH %graph_uri  { example:%object_id a %object_klass ;
                             w3cGeo:location [ w3cGeo:long %longitude ; w3cGeo:lat %latitude ; w3cGeo:alt %altitude ] } }""" ;
                 askcore_queries:binding [ foaf:name "graph_uri"    ; xsi:type xsd:uri ] ;
                 askcore_queries:binding [ foaf:name "object_id"    ; xsi:type xsd:string ; dc:description "unique ID representing the object" ] ;
                 askcore_queries:binding [ foaf:name "object_klass" ; xsi:type xsd:uri ] ;
                 askcore_queries:binding [ foaf:name "longitude"    ; xsi:type xsd:decimal ] ;
                 askcore_queries:binding [ foaf:name "latitude"     ; xsi:type xsd:decimal ] ;
                 askcore_queries:binding [ foaf:name "altitude"     ; xsi:type xsd:decimal ] .
 
<salient_object_select_by_class> dc:description "Return the list of salient objects of a specific class" ;
                 foaf:name "salient_object_select_by_class" ;
                 askcore_queries:query """PREFIX example: <http://example.org/>
PREFIX w3cGeo: <http://www.w3.org/2003/01/geo/wgs84_pos#>
 
SELECT * FROM %graph_uri WHERE { ?uri a example:%object_klass ;
                             w3cGeo:location [ w3cGeo:long ?longitude ; w3cGeo:lat ?latitude ; w3cGeo:alt ?altitude ] }""" ;
                 askcore_queries:binding [ foaf:name "graph_uri"    ; xsi:type xsd:uri ] ;
                 askcore_queries:binding [ foaf:name "object_klass" ; xsi:type xsd:uri ] .

Programming with kDBQueries

kDBQueries is available for C++, Python and Qt/QML.

C++

kDBQueries for C++ relies on a code generator (called kDBQueries) that reads the RDF description of the queries and generate a set of C++ classes.

The executable takes the following arguments:

kDBQueriesGenerator [quries_definition_graph] [namespaces_class] [output_prefix]

When compiling, CMake it is possible to use a macro to generate the C++ classes:

kdb_generate_queries([quries_definition_graph] [namespaces_class] [output_prefix])

In both cases, [quries_definition_graph] corresponds to the RDF file with a description of the query, [namespaces_class] is the namespace where the classes are generated and finally [output_prefix] is the prefix for the .cpp and .h files generated.

Python

kDBQueries for Python read the RDF description of the queries from a RDF Graph stored in the database and dynamically generates the API.

import kDBQueries
import 
 
connection =
kdb_interface   = kDBQueries.interface(connection)
lrs_queries_gen = kDBQueries.generator(self.kdb_interface, "http://example.org/queries")
lrs_queries_gen.salient_object_insert(graph_uri="http://example.org/sp_graph", object_klass="http://example.org/klass", longitude=1, latitude=2, altitude=3)
 
for obj in lrs_queries_gen.salient_object_select_by_class(graph_uri="http://example.org/sp_graph", object_klass="http://example.org/klass"):
  print(obj.uri, obj.longitude, obj.latitude, obj.altitude)

Qt/QML

kDBQueries for QML provides the GeneratedQuery qml object:

import kDBQueries
 
GeneratedQuery
{
  queries: "http://example.org/queries"
  queryName: "salient_object_insert"
  parameters: { graph_uri: "http://example.org/sp_graph", object_klass: "http://example.org/klass", longitude: 1, latitude: 2, altitude: 3 }
}