org.openrdf.query.algebra.evaluation.federation

Class RepositoryFederatedService

java.lang.Object

org.openrdf.query.algebra.evaluation.federation.RepositoryFederatedService

All Implemented Interfaces:

FederatedService

Direct Known Subclasses:

SPARQLFederatedService

public class RepositoryFederatedService
extends Object
implements 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 RepositoryConnection	conn
protected Repository	rep
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
protected static StringBuilder	appendLiteral(StringBuilder sb, Literal lit) Append the literal to the stringbuilder: "myLiteral"^^
protected static StringBuilder	appendURI(StringBuilder sb, URI uri) Append the uri to the stringbuilder, i.e.
protected StringBuilder	appendValueAsString(StringBuilder sb, Value value)
boolean	ask(Service service, BindingSet bindings, String baseUri) Evaluate the provided sparqlQueryString at the initialized Repository of this FederatedService.
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.
protected CloseableIteration<BindingSet,QueryEvaluationException>	evaluateInternal(Service service, CloseableIteration<BindingSet,QueryEvaluationException> bindings, String baseUri) Evaluate the SPARQL query that can be constructed from the SERVICE node at the initialized Repository of this FederatedService.
protected RepositoryConnection	getConnection()
void	initialize() Method to perform any initializations, invoked after construction.
boolean	isInitialized() Method to check if FederatedService.initialize() had been called.
CloseableIteration<BindingSet,QueryEvaluationException>	select(Service service, Set<String> projectionVars, BindingSet bindings, String baseUri) Evaluate the provided sparqlQueryString at the initialized Repository of this FederatedService.
void	shutdown() Method to perform any shutDown code, invoked at unregistering.

Methods inherited from class java.lang.Object

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

Field Detail

rep

protected final Repository rep

shutDown

protected boolean shutDown

conn

protected RepositoryConnection conn

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 CloseableIteration<BindingSet,QueryEvaluationException> select(Service service,
                                                                      Set<String> projectionVars,
                                                                      BindingSet bindings,
                                                                      String baseUri)
                                                               throws QueryEvaluationException

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

Specified by:

select in interface FederatedService

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

Returns:

an iteration over the results of the query

Throws:

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

ask

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

Parameters:

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

bindings - the bindings serving as additional constraints

Returns:

true if at least one result exists

Throws:

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

evaluate

public CloseableIteration<BindingSet,QueryEvaluationException> evaluate(Service service,
                                                                        CloseableIteration<BindingSet,QueryEvaluationException> bindings,
                                                                        String baseUri)
                                                                 throws QueryEvaluationException

Description copied from interface: FederatedService

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 SPARQLFederatedService for a reference implementation

Specified by:

evaluate in interface FederatedService

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.

evaluateInternal

protected CloseableIteration<BindingSet,QueryEvaluationException> evaluateInternal(Service service,
                                                                                   CloseableIteration<BindingSet,QueryEvaluationException> bindings,
                                                                                   String baseUri)
                                                                            throws 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 BINDINGS clause, if this yields an exception fall back to the naive implementation. This method deals with SILENT SERVICEs.

Throws:

QueryEvaluationException

initialize

public void initialize()
                throws QueryEvaluationException

Description copied from interface: FederatedService

Method to perform any initializations, invoked after construction.

Specified by:

initialize in interface FederatedService

Throws:

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

isInitialized

public boolean isInitialized()

Description copied from interface: FederatedService

Method to check if FederatedService.initialize() had been called.

Specified by:

isInitialized in interface FederatedService

shutdown

public void shutdown()
              throws QueryEvaluationException

Description copied from interface: FederatedService

Method to perform any shutDown code, invoked at unregistering.

Specified by:

shutdown in interface FederatedService

Throws:

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

getConnection

protected RepositoryConnection getConnection()
                                      throws RepositoryException

Throws:

RepositoryException

appendValueAsString

protected StringBuilder appendValueAsString(StringBuilder sb,
                                            Value value)

appendURI

protected static StringBuilder appendURI(StringBuilder sb,
                                         URI uri)

Append the uri to the stringbuilder, i.e. .

Parameters:

sb -

uri -

Returns:

the StringBuilder, for convenience

appendLiteral

protected static StringBuilder appendLiteral(StringBuilder sb,
                                             Literal lit)

Append the literal to the stringbuilder: "myLiteral"^^

Parameters:

sb -

lit -

Returns:

the StringBuilder, for convenience