Class RepositoryFederatedService
- java.lang.Object
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- org.eclipse.rdf4j.repository.sparql.federation.RepositoryFederatedService
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- All Implemented Interfaces:
FederatedService
- Direct Known Subclasses:
RepositoryFederatedService,SPARQLFederatedService
public class RepositoryFederatedService extends Object implements FederatedService
Federated Service wrapping theRepositoryto communicate with a SPARQL endpoint.- Author:
- Andreas Schwarte
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Field Summary
Fields Modifier and Type Field Description protected intboundJoinBlockSizeThe number of bindings sent in a single subquery inevaluate(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 requestsprotected booleanshutDown
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Constructor Summary
Constructors Constructor Description RepositoryFederatedService(Repository repo)RepositoryFederatedService(Repository repo, boolean shutDown)
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description booleanask(Service service, BindingSet bindings, String baseUri)Evaluate the provided sparqlQueryString at the initializedRepositoryof thisFederatedService.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 initializedRepositoryof thisFederatedService.intgetBoundJoinBlockSize()protected RepositoryConnectiongetConnection()Retrieve a (re-usable) connection.voidinitialize()Method to perform any initializations, invoked after construction.protected StringinsertValuesClause(String queryString, String valuesClause)Insert the constructed VALUES clause in the beginning of the WHERE block.booleanisInitialized()Method to check ifFederatedService.initialize()had been called.CloseableIteration<BindingSet,QueryEvaluationException>select(Service service, Set<String> projectionVars, BindingSet bindings, String baseUri)Evaluate the provided sparqlQueryString at the initializedRepositoryof thisFederatedService.voidsetBoundJoinBlockSize(int boundJoinBlockSize)voidsetUseFreshConnection(boolean flag)voidshutdown()Method to perform any shutDown code, invoked at unregistering.
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Field Detail
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boundJoinBlockSize
protected int boundJoinBlockSize
The number of bindings sent in a single subquery inevaluate(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
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shutDown
protected boolean shutDown
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Constructor Detail
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RepositoryFederatedService
public RepositoryFederatedService(Repository repo)
- Parameters:
repo- the repository to be used
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RepositoryFederatedService
public RepositoryFederatedService(Repository repo, boolean shutDown)
- Parameters:
repo- the repository to be usedshutDown- a flag indicating whether the repository shall be closed inshutdown()
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Method Detail
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select
public CloseableIteration<BindingSet,QueryEvaluationException> select(Service service, Set<String> projectionVars, BindingSet bindings, String baseUri) throws QueryEvaluationException
Evaluate the provided sparqlQueryString at the initializedRepositoryof thisFederatedService. Insert bindings into SELECT query and evaluate- Specified by:
selectin interfaceFederatedService- 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 evaluationbindings- 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.
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ask
public boolean ask(Service service, BindingSet bindings, String baseUri) throws QueryEvaluationException
Evaluate the provided sparqlQueryString at the initializedRepositoryof thisFederatedService. Insert bindings, send ask query and return final result- Specified by:
askin interfaceFederatedService- Parameters:
service- the reference to the service node, contains additional meta information (vars, prefixes)bindings- the bindings serving as additional constraints- Returns:
trueif at least one result exists- Throws:
QueryEvaluationException- If there was an exception generated while evaluating the query.
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evaluate
public CloseableIteration<BindingSet,QueryEvaluationException> evaluate(Service service, CloseableIteration<BindingSet,QueryEvaluationException> bindings, String baseUri) throws QueryEvaluationException
Description copied from interface:FederatedServiceEvaluate 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
SPARQLFederatedServicefor a reference implementation- Specified by:
evaluatein interfaceFederatedService- Parameters:
service- the reference to the service node, contains information to construct the querybindings- 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.
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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 initializedRepositoryof thisFederatedService. 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:
QueryEvaluationException
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insertValuesClause
protected String insertValuesClause(String queryString, String valuesClause)
Insert the constructed VALUES clause in the beginning of the WHERE block. Also adds theROW_IDX_VARprojection if it is not already present.- Parameters:
queryString- the SELECT query string from the SERVICE nodevaluesClause- the constructed VALUES clause- Returns:
- the final String
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initialize
public void initialize() throws QueryEvaluationExceptionDescription copied from interface:FederatedServiceMethod to perform any initializations, invoked after construction.- Specified by:
initializein interfaceFederatedService- Throws:
QueryEvaluationException- If there was an exception generated while initializing the service.
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isInitialized
public boolean isInitialized()
Description copied from interface:FederatedServiceMethod to check ifFederatedService.initialize()had been called.- Specified by:
isInitializedin interfaceFederatedService
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getBoundJoinBlockSize
public int getBoundJoinBlockSize()
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setBoundJoinBlockSize
public void setBoundJoinBlockSize(int boundJoinBlockSize)
- Parameters:
boundJoinBlockSize- the bound join block size, 0 to evaluate all in a single request
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setUseFreshConnection
public void setUseFreshConnection(boolean flag)
- Parameters:
flag- whether to use a freshRepositoryConnectionfor each individual query
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shutdown
public void shutdown() throws QueryEvaluationExceptionDescription copied from interface:FederatedServiceMethod to perform any shutDown code, invoked at unregistering.- Specified by:
shutdownin interfaceFederatedService- Throws:
QueryEvaluationException- If there was an exception generated while shutting down the service.
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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
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