org.openrdf.query.algebra.evaluation.federation

Interface FederatedService

All Known Implementing Classes:

SPARQLFederatedService

public interface FederatedService

FederatedService to allow for customized evaluation of SERVICE expression. By default SPARQLFederatedService is used.

Author:

Andreas Schwarte

See Also:

SPARQLFederatedService

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	FederatedService.QueryType Query type

Method Summary

Modifier and Type	Method and Description
CloseableIteration<BindingSet,QueryEvaluationException>	evaluate(Service service, CloseableIteration<BindingSet,QueryEvaluationException> bindings, String baseUri) Evaluate the provided SPARQL query at this federated service, possibilities for vectored evaluation.
CloseableIteration<BindingSet,QueryEvaluationException>	evaluate(String sparqlQueryString, BindingSet bindings, String baseUri, FederatedService.QueryType type, Service service) Evaluate the provided SPARQL query at this federated service.
void	initialize() Method to perform any initializations, invoked after construction.
void	shutdown() Method to perform any shutDown code, invoked at unregistering.

Method Detail

evaluate

CloseableIteration<BindingSet,QueryEvaluationException> evaluate(String sparqlQueryString,
                                                                 BindingSet bindings,
                                                                 String baseUri,
                                                                 FederatedService.QueryType type,
                                                                 Service service)
                                                          throws QueryEvaluationException

Evaluate the provided SPARQL query at this federated service.

Important: The original bindings need to be inserted into the result, e.g. via InsertBindingSetCursor.

 Expected behavior:
 a) SELECT: evaluate the given SPARQL query using the bindings as constraints
 b) ASK: evaluate boolean query using the bindings as constraints
                - true => return new SingletonIteration(bindings);
      - false => return new EmptyIteration();
 

Parameters:

sparqlQueryString - a SPARQL query (either SELECT or ASK, compare type parameter)

bindings - the bindings serving as additional constraints

baseUri -

type - the FederatedService.QueryType, either ASK or SELECT

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

Returns:

an iteration over the results of the query

Throws:

QueryEvaluationException

evaluate

CloseableIteration<BindingSet,QueryEvaluationException> evaluate(Service service,
                                                                 CloseableIteration<BindingSet,QueryEvaluationException> 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, e.g. via InsertBindingSetCursor.
• SILENT service must be dealt with in the method

Compare 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

initialize

void initialize()
         throws RepositoryException

Method to perform any initializations, invoked after construction.

Throws:

RepositoryException

shutdown

void shutdown()
       throws RepositoryException

Method to perform any shutDown code, invoked at unregistering.

Throws:

RepositoryException