Class RepositoryFederatedService
java.lang.Object
org.eclipse.rdf4j.repository.sparql.federation.RepositoryFederatedService
- All Implemented Interfaces:
FederatedService
- Direct Known Subclasses:
SPARQLFederatedService
Federated Service wrapping the
Repository
to communicate with a SPARQL endpoint.- Author:
- Andreas Schwarte
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Field Summary
Modifier and TypeFieldDescriptionprotected int
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 requestsprotected boolean
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Constructor Summary
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Method Summary
Modifier and TypeMethodDescriptionboolean
ask
(Service service, BindingSet bindings, String baseUri) Evaluate the provided sparqlQueryString at the initializedRepository
of thisFederatedService
.evaluate
(Service service, CloseableIteration<BindingSet> bindings, String baseUri) Evaluate the provided SPARQL query at this federated service, possibilities for vectored evaluation.protected CloseableIteration
<BindingSet> evaluateInternal
(Service service, CloseableIteration<BindingSet> bindings, String baseUri) Evaluate the SPARQL query that can be constructed from the SERVICE node at the initializedRepository
of thisFederatedService
.int
protected RepositoryConnection
Retrieve a (re-usable) connection.void
Method to perform any initializations, invoked after construction.protected String
insertValuesClause
(String queryString, String valuesClause) Insert the constructed VALUES clause in the beginning of the WHERE block.boolean
Method to check ifFederatedService.initialize()
had been called.Evaluate the provided sparqlQueryString at the initializedRepository
of thisFederatedService
.void
setBoundJoinBlockSize
(int boundJoinBlockSize) void
setUseFreshConnection
(boolean flag) void
shutdown()
Method to perform any shutDown code, invoked at unregistering.
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Field Details
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boundJoinBlockSize
protected int boundJoinBlockSizeThe 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 -
shutDown
protected boolean shutDown
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Constructor Details
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RepositoryFederatedService
- Parameters:
repo
- the repository to be used
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RepositoryFederatedService
- Parameters:
repo
- the repository to be usedshutDown
- a flag indicating whether the repository shall be closed inshutdown()
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Method Details
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select
public CloseableIteration<BindingSet> select(Service service, Set<String> projectionVars, BindingSet bindings, String baseUri) throws QueryEvaluationException Evaluate the provided sparqlQueryString at the initializedRepository
of thisFederatedService
. Insert bindings into SELECT query and evaluate- Specified by:
select
in 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 constraintsbaseUri
-- 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 initializedRepository
of thisFederatedService
. Insert bindings, send ask query and return final result- Specified by:
ask
in interfaceFederatedService
- Parameters:
service
- the reference to the service node, contains additional meta information (vars, prefixes)bindings
- the bindings serving as additional constraintsbaseUri
-- Returns:
true
if 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> evaluate(Service service, CloseableIteration<BindingSet> 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
invalid reference
org.eclipse.rdf4j.query.algebra.evaluation.federation.SPARQLFederatedService
- Specified by:
evaluate
in 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> evaluateInternal(Service service, CloseableIteration<BindingSet> bindings, String baseUri) throws QueryEvaluationException Evaluate the SPARQL query that can be constructed from the SERVICE node at the initializedRepository
of 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
Insert the constructed VALUES clause in the beginning of the WHERE block. Also adds theROW_IDX_VAR
projection 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
Description copied from interface:FederatedService
Method to perform any initializations, invoked after construction.- Specified by:
initialize
in 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:FederatedService
Method to check ifFederatedService.initialize()
had been called.- Specified by:
isInitialized
in interfaceFederatedService
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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
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setUseFreshConnection
public void setUseFreshConnection(boolean flag) - Parameters:
flag
- whether to use a freshRepositoryConnection
for each individual query
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shutdown
Description copied from interface:FederatedService
Method to perform any shutDown code, invoked at unregistering.- Specified by:
shutdown
in interfaceFederatedService
- Throws:
QueryEvaluationException
- If there was an exception generated while shutting down the service.
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getConnection
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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