org.eclipse.rdf4j.repository.sparql.federation

Class RepositoryFederatedService

java.lang.Object

org.eclipse.rdf4j.repository.sparql.federation.RepositoryFederatedService

All Implemented Interfaces:

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

Direct Known Subclasses:

SPARQLFederatedService

public class RepositoryFederatedService
extends Object
implements org.eclipse.rdf4j.query.algebra.evaluation.federation.FederatedService

Federated Service wrapping the Repository to communicate with a SPARQL endpoint.

Author:

Andreas Schwarte

Field Summary

Fields

Modifier and Type	Field and Description
protected int	boundJoinBlockSize The number of bindings sent in a single subquery in evaluate(Service, CloseableIteration, String) If blockSize is set to 0, the entire input stream is used as block input the block size effectively determines the number of remote requests
protected boolean	shutDown

Constructor Summary

Constructors

Constructor and Description
RepositoryFederatedService(Repository repo)
RepositoryFederatedService(Repository repo, boolean shutDown)

Method Summary

Modifier and Type	Method and Description
boolean	ask(org.eclipse.rdf4j.query.algebra.Service service, org.eclipse.rdf4j.query.BindingSet bindings, String baseUri) Evaluate the provided sparqlQueryString at the initialized Repository of this FederatedService.
org.eclipse.rdf4j.common.iteration.CloseableIteration<org.eclipse.rdf4j.query.BindingSet,org.eclipse.rdf4j.query.QueryEvaluationException>	evaluate(org.eclipse.rdf4j.query.algebra.Service service, org.eclipse.rdf4j.common.iteration.CloseableIteration<org.eclipse.rdf4j.query.BindingSet,org.eclipse.rdf4j.query.QueryEvaluationException> bindings, String baseUri)
protected org.eclipse.rdf4j.common.iteration.CloseableIteration<org.eclipse.rdf4j.query.BindingSet,org.eclipse.rdf4j.query.QueryEvaluationException>	evaluateInternal(org.eclipse.rdf4j.query.algebra.Service service, org.eclipse.rdf4j.common.iteration.CloseableIteration<org.eclipse.rdf4j.query.BindingSet,org.eclipse.rdf4j.query.QueryEvaluationException> bindings, String baseUri) Evaluate the SPARQL query that can be constructed from the SERVICE node at the initialized Repository of this FederatedService.
int	getBoundJoinBlockSize()
protected RepositoryConnection	getConnection() Retrieve a (re-usable) connection.
void	initialize()
protected String	insertValuesClause(String queryString, String valuesClause) Insert the constructed VALUES clause in the beginning of the WHERE block.
boolean	isInitialized()
org.eclipse.rdf4j.common.iteration.CloseableIteration<org.eclipse.rdf4j.query.BindingSet,org.eclipse.rdf4j.query.QueryEvaluationException>	select(org.eclipse.rdf4j.query.algebra.Service service, Set<String> projectionVars, org.eclipse.rdf4j.query.BindingSet bindings, String baseUri) Evaluate the provided sparqlQueryString at the initialized Repository of this FederatedService.
void	setBoundJoinBlockSize(int boundJoinBlockSize)
void	setUseFreshConnection(boolean flag)
void	shutdown()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

boundJoinBlockSize

protected int boundJoinBlockSize

The number of bindings sent in a single subquery in evaluate(Service, CloseableIteration, String) If blockSize is set to 0, the entire input stream is used as block input the block size effectively determines the number of remote requests

shutDown

protected boolean shutDown

Constructor Detail

RepositoryFederatedService

public RepositoryFederatedService(Repository repo)

Parameters:

repo - the repository to be used

RepositoryFederatedService

public RepositoryFederatedService(Repository repo,
                                  boolean shutDown)

Parameters:

repo - the repository to be used

shutDown - a flag indicating whether the repository shall be closed in shutdown()

Method Detail

select

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

Evaluate the provided sparqlQueryString at the initialized Repository of this FederatedService. Insert bindings into SELECT query and evaluate

Specified by:

select in interface org.eclipse.rdf4j.query.algebra.evaluation.federation.FederatedService

Throws:

org.eclipse.rdf4j.query.QueryEvaluationException

ask

public boolean ask(org.eclipse.rdf4j.query.algebra.Service service,
                   org.eclipse.rdf4j.query.BindingSet bindings,
                   String baseUri)
            throws org.eclipse.rdf4j.query.QueryEvaluationException

Evaluate the provided sparqlQueryString at the initialized Repository of this FederatedService. Insert bindings, send ask query and return final result

Specified by:

ask in interface org.eclipse.rdf4j.query.algebra.evaluation.federation.FederatedService

Throws:

org.eclipse.rdf4j.query.QueryEvaluationException

evaluate

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

Specified by:

evaluate in interface org.eclipse.rdf4j.query.algebra.evaluation.federation.FederatedService

Throws:

org.eclipse.rdf4j.query.QueryEvaluationException

evaluateInternal

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

Evaluate the SPARQL query that can be constructed from the SERVICE node at the initialized Repository of this FederatedService. Use specified bindings as constraints to the query. Try to evaluate using VALUES clause, if this yields an exception fall back to the naive implementation. This method deals with SILENT SERVICEs.

Throws:

org.eclipse.rdf4j.query.QueryEvaluationException

insertValuesClause

protected String insertValuesClause(String queryString,
                                    String valuesClause)

Insert the constructed VALUES clause in the beginning of the WHERE block. Also adds the ROW_IDX_VAR projection if it is not already present.

Parameters:

queryString - the SELECT query string from the SERVICE node

valuesClause - the constructed VALUES clause

Returns:

the final String

initialize

public void initialize()
                throws org.eclipse.rdf4j.query.QueryEvaluationException

Specified by:

initialize in interface org.eclipse.rdf4j.query.algebra.evaluation.federation.FederatedService

Throws:

org.eclipse.rdf4j.query.QueryEvaluationException

isInitialized

public boolean isInitialized()

Specified by:

isInitialized in interface org.eclipse.rdf4j.query.algebra.evaluation.federation.FederatedService

getBoundJoinBlockSize

public int getBoundJoinBlockSize()

setBoundJoinBlockSize

public void setBoundJoinBlockSize(int boundJoinBlockSize)

Parameters:

boundJoinBlockSize - the bound join block size, 0 to evaluate all in a single request

setUseFreshConnection

public void setUseFreshConnection(boolean flag)

Parameters:

flag - whether to use a fresh RepositoryConnection for each individual query

shutdown

public void shutdown()
              throws org.eclipse.rdf4j.query.QueryEvaluationException

Specified by:

shutdown in interface org.eclipse.rdf4j.query.algebra.evaluation.federation.FederatedService

Throws:

org.eclipse.rdf4j.query.QueryEvaluationException

getConnection

protected RepositoryConnection getConnection()
                                      throws RepositoryException

Retrieve a (re-usable) connection. If it is not yet created, open a fresh connection. Note that this connection is closed automatically when shutting this service.

Returns:

connection

Throws:

RepositoryException