owlObjectRequest

There are two SPARQL request-response Service requests in the Jena module:

• owlRequest: this service answers to SPARQL requests to the Jena framework. The service returns the results as a formatted or XML content
• http://dassault-aviation.com/jena:owlObjectRequest: this service answers to SPARQL requests to the Jena framework and return the results as results as an object

Contrary to the owlRequest service, the http://dassault-aviation.com/jena:owlObjectRequest service return the results as a org.da.protoframework.jena.common.QueryResult object.

Note that the request itself can be generated using the SparqlRequest utility.

Service datas

The datas of the request are:

• reqSchema: the key of the OWL schema to use for the request, must correspond to the name of one of the owlSchemas in the properties
• query: the SPARQL query without the prefix. For example we could have:

              SELECT ?pizza 
              WHERE {
                 ?pizza a owl:Class ;
                 rdfs:subClassOf ?restriction.
                 ?restriction owl:onProperty pizza:hasTopping ;
                 owl:someValuesFrom pizza:PeperoniSausageTopping
              }
  

• stripPrefix: a boolean indicating if the prefix of the response results must be retained or stripped from the results
• orderedBy: the name of the class used to order the results

The datas of the reponse are:

• respSchema: the key of the OWL schema which was used for the request
• response: the response as a QueryResults object
• requestStatus: the status which can be NO_SCHEMA if there was no OWL schema associated with the key, INVALID, if the request was invalid, and VALID if the request was valid

Response content

The response data is a QueryResults object, which gives the list of results of the query. The API of this class is:

public class org.da.protoframework.jena.common.QueryResults

Modifier and Type	Method and Description
int	countResults() Return the number of results of the query
QueryResults.Result	getFirstResult() Return the first result for the query
List<QueryResults.Result>	getOrderedResultsList() Return the ordered list of results
Map<String, QueryResults.Result>	getResults() Return all the results for the query. Note that it will return null if there are no results
boolean	hasResults() Return true if there is at least one result for the query

Note that the key of the result Map will be the SELECT variable used to order the result (by the orderedBy data). If this variable was not part of the SELECT variables, then it will be the first encountered variable in the columns.

QueryResults.Result

A QueryResults.Result contains the list of columns (ie corresponding to variables) for this result. This class has the following API:

public class org.da.protoframework.jena.common.QueryResults.Result

Modifier and Type	Method and Description
int	countValues() Return the number of values, which correspond to the nulber of variables declared in the SELECT construct
String	getKey() Return the key of the result, corresponding to the variable returned in the result Map
Map<String, QueryResults.Value>	getResults() Return all the values for the result, corresponding to the list of variables declared in the SELECT construct. The key of the Map is the variable name
QueryResults.Value	getValue(Strng key) Return the value for a specified key (ie variable name)
Map<String, Value>	getValues() Return ther first result for the query

QueryResults.Value

A QueryResults.Result contains the value for one column (ie corresponding to a variable) for a result. This class has the following API:

public class org.da.protoframework.jena.common.QueryResults.Value

Modifier and Type	Method and Description
Object	getValue() Return the associated value
byte	getValueAsByte() Return the associated value as a byte
char	getValueAsChar() Return the associated value as a char
double	getValueAsDouble() Return the associated value as a double
float	getValueAsFloat() Return the associated value as a float
int	getValueAsInt() Return the associated value as an int
long	getValueAsLong() Return the associated value as a long
short	getValueAsShort() Return the associated value as a short
String	getValueAsString() Return the associated value as a String

Example

Suppose the following query:

      SELECT ?number ?type
      WHERE { 
         ?alarm rdf:type inav:Alarm .
         ?alarm inav:AlarmNumber ?number .
         ?alarm inav:hasAlarmType ?type .
      }    

The following code will print the ?number and ?type of each result:

      public void subscribe(ServiceInstance service) {
         QueryResults results = (QueryResults) service.getData("response").getValue();
         Iterator<QueryResults.Result> it = results.getOrderedResultsList().iterator();
         while (it.hasNext()) {
          QueryResults.Result result = it.next();
           int number = result.getValue("number").getValueAsInt();
           String type = result.getValue("type").getValueAsString();
           System.out.println("Alarm " + number + ": " + type);
         }
      }