Package org.eclipse.rdf4j.query.algebra.evaluation.federation

Interface FederatedService

public interface FederatedService

FederatedService to allow for customized evaluation of SERVICE expression. By default org.eclipse.rdf4j.query.algebra.evaluation.federation.SPARQLFederatedService is used.

Author:

Andreas Schwarte, James Leigh

See Also:

org.eclipse.rdf4j.query.algebra.evaluation.federation.SPARQLFederatedService

Method Summary

Modifier and Type	Method	Description
boolean	ask(Service service, BindingSet bindings, String baseUri)	Evaluate the provided SPARQL ASK query at this federated service.
org.eclipse.rdf4j.common.iteration.CloseableIteration<BindingSet>	evaluate(Service service, org.eclipse.rdf4j.common.iteration.CloseableIteration<BindingSet> bindings, String baseUri)	Evaluate the provided SPARQL query at this federated service, possibilities for vectored evaluation.
void	initialize()	Method to perform any initializations, invoked after construction.
boolean	isInitialized()	Method to check if initialize() had been called.
org.eclipse.rdf4j.common.iteration.CloseableIteration<BindingSet>	select(Service service, Set<String> projectionVars, BindingSet bindings, String baseUri)	Evaluate the provided SPARQL query at this federated service.
void	shutdown()	Method to perform any shutDown code, invoked at unregistering.

Method Detail

ask

boolean ask(Service service,
            BindingSet bindings,
            String baseUri)
     throws QueryEvaluationException

Evaluate the provided SPARQL ASK query at this federated service.

 Expected behavior: evaluate boolean query using the bindings as constraints
 

Parameters:

service - the reference to the service node, contains additional meta information (vars, prefixes)

bindings - the bindings serving as additional constraints

baseUri -

Returns:

true if at least one result exists

Throws:

QueryEvaluationException - If there was an exception generated while evaluating the query.

select

org.eclipse.rdf4j.common.iteration.CloseableIteration<BindingSet> select(Service service,
                                                                         Set<String> projectionVars,
                                                                         BindingSet bindings,
                                                                         String baseUri)
                                                                  throws QueryEvaluationException

Evaluate the provided SPARQL query at this federated service.

Important: The original bindings need to be inserted into the result.

 Expected behavior: evaluate the given SPARQL query using the bindings as constraints
 

Parameters:

service - the reference to the service node, contains additional meta information (vars, prefixes)

projectionVars - The variables with unknown value that should be projected from this evaluation

bindings - the bindings serving as additional constraints

baseUri -

Returns:

an iteration over the results of the query

Throws:

QueryEvaluationException - If there was an exception generated while evaluating the query.

evaluate

org.eclipse.rdf4j.common.iteration.CloseableIteration<BindingSet> evaluate(Service service,
                                                                           org.eclipse.rdf4j.common.iteration.CloseableIteration<BindingSet> bindings,
                                                                           String baseUri)
                                                                    throws QueryEvaluationException

Evaluate the provided SPARQL query at this federated service, possibilities for vectored evaluation.

Contracts:

• The original bindings need to be inserted into the result
• SILENT service must be dealt with in the method

Compare org.eclipse.rdf4j.query.algebra.evaluation.federation.SPARQLFederatedService for a reference implementation

Parameters:

service - the reference to the service node, contains information to construct the query

bindings - the bindings serving as additional constraints (for vectored evaluation)

baseUri - the baseUri

Returns:

the result of evaluating the query using bindings as constraints, the original bindings need to be inserted into the results!

Throws:

QueryEvaluationException - If there was an exception generated while evaluating the query.

isInitialized

boolean isInitialized()

Method to check if initialize() had been called.

initialize

void initialize()
         throws QueryEvaluationException

Method to perform any initializations, invoked after construction.

Throws:

QueryEvaluationException - If there was an exception generated while initializing the service.

shutdown

void shutdown()
       throws QueryEvaluationException

Method to perform any shutDown code, invoked at unregistering.

Throws:

QueryEvaluationException - If there was an exception generated while shutting down the service.