org.apache.clerezza.rdf.cris

Class GraphIndexer

java.lang.Object

org.apache.clerezza.rdf.cris.ResourceFinder

org.apache.clerezza.rdf.cris.GraphIndexer

public class GraphIndexer
extends ResourceFinder

Creates an index of RDF resources and provides an interface to search for indexed resources.

Author:

reto, tio, daniel

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEFAULT_MAXHITS Default value for maxhits.

Constructor Summary

Constructors

Constructor and Description
GraphIndexer(TripleCollection definitionGraph, TripleCollection baseGraph) Creates a new in-memory index with default maxHits.
GraphIndexer(TripleCollection definitionGraph, TripleCollection baseGraph, org.apache.lucene.store.Directory indexDirectory, boolean createNewIndex) Creates a new index with default maxHits.
GraphIndexer(TripleCollection definitionGraph, TripleCollection baseGraph, org.apache.lucene.store.Directory indexDirectory, boolean createNewIndex, int maxHits) Creates a new index.

Method Summary

Methods

Modifier and Type	Method and Description
void	closeLuceneIndex() Releases resources held by GraphIndexer.
void	finalize()
List<NonLiteral>	findResources(List<? extends Condition> conditions, SortSpecification sortSpecification, FacetCollector... facetCollectors) Find resources using conditions and collect facets and a sort order.
List<NonLiteral>	findResources(List<? extends Condition> conditions, SortSpecification sortSpecification, List<FacetCollector> facetCollectors, int from, int to) Find resources using conditions and collect facets and specify a sort order.
org.apache.lucene.analysis.Analyzer	getAnalyzer() Returns the Analyzer used by this GraphIndexer instance.
TripleCollection	getBaseGraph() Returns the graph that this GraphIndexer builds an index on.
TripleCollection	getDefinitionGraph() Returns the graph where the index definitions are stored.
int	getMaxHits() How many results a search on the index returns maximally.
protected void	indexResource(Resource resource, org.apache.lucene.index.IndexWriter writer) Index a resource.
void	optimizeIndex() optimize the index
protected void	processDefinitions() Read the index definitions and initialize the GraphIndexer with them.
void	reCreateIndex() recreates the index
protected void	scheduleForReindex(Resource resource) Schedule an update or creation of an index for a resource.
void	scheduleIndexOptimizations(long delay, long period) Schedule optimizations for repeated executions.
void	setMaxHits(int maxHits) Set how many results a search on the index returns maximally.
void	terminateIndexOptimizationSchedule() Cancel scheduled optimizations.

Methods inherited from class org.apache.clerezza.rdf.cris.ResourceFinder

findResources, findResources, findResources, findResources, findResources, findResources, findResources, findResources, findResources, findResources

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_MAXHITS

public static final int DEFAULT_MAXHITS

Default value for maxhits.

See Also:

Constant Field Values

Constructor Detail

GraphIndexer

public GraphIndexer(TripleCollection definitionGraph,
            TripleCollection baseGraph,
            org.apache.lucene.store.Directory indexDirectory,
            boolean createNewIndex,
            int maxHits)

Creates a new index. The GraphIndexer looks for specifications of what properties on what resources to index in the definitionGraph. The baseGraph specifies the graph on which the index is built.

Notes:

This is an expensive operation and it is advisable to call closeLuceneIndex() when this instance is no longer needed.

The GraphIndexer must have write-access to the index directory specified.

Parameters:

definitionGraph - where index definitions are stored

baseGraph - where the resources to index are stored

indexDirectory - The directory where the index is stored.

createNewIndex - Whether to create a new index or reuse an existing one. The constructor does not check if there is a valid exiting index. The user is responsible for setting this value correctly.

maxHits - How many results the indexer returns. All entries in the index are searched, but only @code{maxHits} resources are resolved and returned in the result.

See Also:

IndexDefinitionManager

GraphIndexer

public GraphIndexer(TripleCollection definitionGraph,
            TripleCollection baseGraph,
            org.apache.lucene.store.Directory indexDirectory,
            boolean createNewIndex)

Creates a new index with default maxHits. The GraphIndexer looks for specifications of what properties on what resources to index in the definitionGraph. The baseGraph specifies the graph on which the index is built.

Notes:

This is an expensive operation and it is advisable to call closeLuceneIndex() when this instance is no longer needed.

The GraphIndexer must have write-access to the index directory specified.

Parameters:

definitionGraph - where index definitions are stored

baseGraph - where the resources to index are stored

indexDirectory - The directory where the index is stored.

createNewIndex - Whether to create a new index or reuse an existing one. The constructor does not check if there is a valid exiting index. The user is responsible for setting this value correctly.

GraphIndexer

public GraphIndexer(TripleCollection definitionGraph,
            TripleCollection baseGraph)

Creates a new in-memory index with default maxHits. The GraphIndexer looks for specifications of what properties on what resources to index in the definitionGraph. The baseGraph specifies the graph on which the index is built.

Notes:

This is an expensive operation and it is advisable to call closeLuceneIndex() when this instance is no longer needed.

The GraphIndexer must have write-access to the index directory specified.

Parameters:

definitionGraph - where index definitions are stored

baseGraph - where the resources to index are stored

Method Detail

closeLuceneIndex

public void closeLuceneIndex()

Releases resources held by GraphIndexer. After the call to this method, this GraphIndexer instance must not be used anymore.

getAnalyzer

public org.apache.lucene.analysis.Analyzer getAnalyzer()

Returns the Analyzer used by this GraphIndexer instance.

Returns:

the Analyzer

getBaseGraph

public TripleCollection getBaseGraph()

Returns the graph that this GraphIndexer builds an index on.

Returns:

The graph containing the indexed resources.

getDefinitionGraph

public TripleCollection getDefinitionGraph()

Returns the graph where the index definitions are stored.

Returns:

The graph with the index definitions.

getMaxHits

public int getMaxHits()

How many results a search on the index returns maximally.

Returns:

the maximum number of results.

setMaxHits

public void setMaxHits(int maxHits)

Set how many results a search on the index returns maximally.

Parameters:

maxHits - the maximum number of results.

optimizeIndex

public void optimizeIndex()

Description copied from class: ResourceFinder

optimize the index

Specified by:

optimizeIndex in class ResourceFinder

scheduleIndexOptimizations

public void scheduleIndexOptimizations(long delay,
                              long period)

Schedule optimizations for repeated executions.

Parameters:

delay - The delay before the first execution in milliseconds.

period - Time between successive executions (execution rate) in milliseconds.

terminateIndexOptimizationSchedule

public void terminateIndexOptimizationSchedule()

Cancel scheduled optimizations. This call does not have any effect on optimizations that are being executed while the method is called.

reCreateIndex

public void reCreateIndex()

Description copied from class: ResourceFinder

recreates the index

Specified by:

reCreateIndex in class ResourceFinder

findResources

public List<NonLiteral> findResources(List<? extends Condition> conditions,
                             SortSpecification sortSpecification,
                             FacetCollector... facetCollectors)
                               throws org.apache.lucene.queryparser.classic.ParseException

Description copied from class: ResourceFinder

Find resources using conditions and collect facets and a sort order.

Specified by:

findResources in class ResourceFinder

Parameters:

conditions - a list of conditions to construct a query from.

sortSpecification - specifies the sort order.

facetCollectors - facet collectors to apply to the query result.

Returns:

a list of resources that match the query.

Throws:

org.apache.lucene.queryparser.classic.ParseException - when the resulting query is illegal.

findResources

public List<NonLiteral> findResources(List<? extends Condition> conditions,
                             SortSpecification sortSpecification,
                             List<FacetCollector> facetCollectors,
                             int from,
                             int to)
                               throws org.apache.lucene.queryparser.classic.ParseException

Find resources using conditions and collect facets and specify a sort order. This method allows to specify the indices of the query results to return (e.g. for pagination).

Parameters:

conditions - a list of conditions to construct a query from.

facetCollectors - Facet collectors to apply to the query result. Can be Collections.EMPTY_LIST, if not used.

sortSpecification - Specifies the sort order. Can be null, if not used.

from - return results starting from this index (inclusive).

to - return results until this index (exclusive).

Returns:

a list of resources that match the query.

Throws:

org.apache.lucene.queryparser.classic.ParseException - when the resulting query is illegal.

finalize

public void finalize()
              throws Throwable

Overrides:

finalize in class Object

Throws:

Throwable

scheduleForReindex

protected void scheduleForReindex(Resource resource)

Schedule an update or creation of an index for a resource.

Parameters:

resource - the resource to index.

processDefinitions

protected void processDefinitions()

Read the index definitions and initialize the GraphIndexer with them.

indexResource

protected void indexResource(Resource resource,
                 org.apache.lucene.index.IndexWriter writer)

Index a resource.

Parameters:

resource - the resource to index.

writer - the index writer.