Class QueryManager

java.lang.Object

org.eclipse.rdf4j.federated.QueryManager

public class QueryManager
extends Object

QueryManager to manage queries. a) Management of running queries (abort, finish) b) Factory to create queries

Author:

Andreas Schwarte

Constructor Summary

Constructors

Constructor	Description
QueryManager()

Method Summary

Modifier and Type	Method	Description
void	abortQuery(QueryInfo queryInfo)
void	addPrefixDeclaration(String prefix, String namespace)	Register a prefix declaration to be used during query evaluation.
protected static Set<String>	findQueryPrefixes(String queryString)	Find all prefixes declared in the query
void	finishQuery(QueryInfo queryInfo)
BigInteger	getNextQueryId()	Computes the (incremental) next query identifier.
int	getNumberOfRunningQueries()
protected String	getPrefixDeclarations()	Get the prefix declarations that have to be prepended to the query.
protected String	getPrefixDeclarationsCheck(String queryString)	Get the prefix declarations that have to be added while considering prefixes that are already declared in the query.
String	getQueryPlan(String queryString)	Retrieve the query plan for the given query string.
Set<QueryInfo>	getRunningQueries()
void	init(FedXRepository repo, FederationContext federationContext)
boolean	isRunning(QueryInfo queryInfo)
BooleanQuery	prepareBooleanQuery(String queryString)	Prepare a boolean query which uses the underlying federation to evaluate the query.
GraphQuery	prepareGraphQuery(String queryString)	Prepare a tuple query which uses the underlying federation to evaluate the query.
Query	prepareQuery(String queryString)	Prepare a Query which uses the underlying federation to evaluate the SPARQL query.
TupleQuery	prepareTupleQuery(String queryString)	Prepare a tuple query which uses the underlying federation to evaluate the query.
void	registerQuery(QueryInfo queryInfo)	Add the query to the set of running queries, queries are identified via a unique id
void	shutdown()

Methods inherited from class java.lang.Object

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

Constructor Details

QueryManager

public QueryManager()

Method Details

init

public void init(FedXRepository repo,
 FederationContext federationContext)

shutdown

public void shutdown()

registerQuery

public void registerQuery(QueryInfo queryInfo)

Add the query to the set of running queries, queries are identified via a unique id

Parameters:

queryInfo -

getRunningQueries

public Set<QueryInfo> getRunningQueries()

getNumberOfRunningQueries

public int getNumberOfRunningQueries()

abortQuery

public void abortQuery(QueryInfo queryInfo)

finishQuery

public void finishQuery(QueryInfo queryInfo)

isRunning

public boolean isRunning(QueryInfo queryInfo)

addPrefixDeclaration

public void addPrefixDeclaration(String prefix,
 String namespace)

Register a prefix declaration to be used during query evaluation. If a known prefix is used in a query, it is substituted in the parsing step. If namespace is null, the corresponding entry is removed.

Parameters:

prefix - a common prefix, e.g. rdf

namespace - the corresponding namespace, e.g. "http://www.w3.org/1999/02/22-rdf-syntax-ns#"

prepareTupleQuery

public TupleQuery prepareTupleQuery(String queryString)
                             throws MalformedQueryException

Prepare a tuple query which uses the underlying federation to evaluate the query.

The queryString is modified to use the declared PREFIX declarations, see FedXConfig.getPrefixDeclarations() for details.

Parameters:

queryString -

Returns:

the prepared tuple query

Throws:

MalformedQueryException

prepareGraphQuery

public GraphQuery prepareGraphQuery(String queryString)
                             throws MalformedQueryException

Prepare a tuple query which uses the underlying federation to evaluate the query.

The queryString is modified to use the declared PREFIX declarations, see FedXConfig.getPrefixDeclarations() for details.

Parameters:

queryString -

Returns:

the prepared graph query

Throws:

MalformedQueryException

prepareBooleanQuery

public BooleanQuery prepareBooleanQuery(String queryString)
                                 throws MalformedQueryException

Prepare a boolean query which uses the underlying federation to evaluate the query.

The queryString is modified to use the declared PREFIX declarations, see FedXConfig.getPrefixDeclarations() for details.

Parameters:

queryString -

Returns:

the prepared BooleanQuery

Throws:

MalformedQueryException

prepareQuery

public Query prepareQuery(String queryString)
                   throws MalformedQueryException

Prepare a Query which uses the underlying federation to evaluate the SPARQL query.

The queryString is modified to use the declared PREFIX declarations, see FedXConfig.getPrefixDeclarations() for details.

Parameters:

queryString -

Returns:

the prepared Query

Throws:

MalformedQueryException

getQueryPlan

public String getQueryPlan(String queryString)
                    throws MalformedQueryException,
FedXException

Retrieve the query plan for the given query string.

Parameters:

queryString -

Returns:

the query plan

Throws:

MalformedQueryException

FedXException

getNextQueryId

public BigInteger getNextQueryId()

Computes the (incremental) next query identifier. Implementation is thread safe and synchronized.

Returns:

the next query identifier

getPrefixDeclarations

protected String getPrefixDeclarations()

Get the prefix declarations that have to be prepended to the query.

Returns:

the prefix declarations

getPrefixDeclarationsCheck

protected String getPrefixDeclarationsCheck(String queryString)

Get the prefix declarations that have to be added while considering prefixes that are already declared in the query. The issue here is that duplicate declaration causes exceptions in RDF4J.

Parameters:

queryString -

Returns:

the prefix declarations

findQueryPrefixes

protected static Set<String> findQueryPrefixes(String queryString)

Find all prefixes declared in the query

Parameters:

queryString -

Returns:

the prefixes