com.tinkerpop.blueprints.oupls.sail
Class GraphSail<T extends KeyIndexableGraph>

java.lang.Object
  org.openrdf.sail.helpers.SailBase
      org.openrdf.sail.helpers.NotifyingSailBase
          com.tinkerpop.blueprints.oupls.sail.GraphSail<T>

All Implemented Interfaces:

WrapperGraph<T>, org.openrdf.sail.NotifyingSail, org.openrdf.sail.Sail

public class GraphSail<T extends KeyIndexableGraph>
extends org.openrdf.sail.helpers.NotifyingSailBase
implements WrapperGraph<T>

An RDF storage interface for any graph database with a Blueprints IndexableGraph implementation. It models RDF graphs as property graphs which can be easily traversed and manipulated with other Blueprints-compatible tools. At the same time, it can be used with OpenRDF-based tools to power a SPARQL endpoint, an RDF reasoner, etc.

RDF resources are stored as vertices, RDF statements as edges using the Blueprints default (automatic) indices. Namespaces are stored at a special vertex with the id "urn:com.tinkerpop.blueprints.sail:namespaces".

This Sail is as transactional as the underlying graph database: if the provided Graph implements TransactionalGraph and is in manual transaction mode, then the SailConnection's commit and rollback methods will be used correspondingly.

Retrieval of RDF statements from the store involves both "index-based" and "graph-based" matching, as follows. For each new statement edge which is added to the store, "p" (predicate), "c" (context), and "pc" (predicate and context) property values are added and indexed. These allow the statement to be quickly retrieved in a query where only the predicate and/or context is specified. However, BlueprintsSail will additionally index on any triple pattern which is supplied to the constructor, boosting query reactivity at the expense of additional storage overhead. For example, if a "so" pattern is supplied, each new statement edge will also receive an "so" property value which stores the combination of subject and object of the statement. A subsequent call such as getStatements(john, null, jane) will match both values simultaneously. This may succeed more quickly than the corresponding graph-based match, which picks either the john or jane vertex as a starting point and filters on adjacent edges. Graph-based matches are used for all of the triple patterns s,o,sp,so,sc,po,oc,spo,spc,soc,poc,spoc which have not been explicitly flagged for index-based matching.

Note: this implementation attaches no semantics to Vertex and Edge IDs, so as to be compatible with Graph implementations which do no not allow IDs to be chosen.

Author:

Joshua Shinavier (http://fortytwo.net)

Field Summary

static char	BLANK_NODE_PREFIX
static String	BNODE
static String	CONTEXT_PROP
static Pattern	INDEX_PATTERN
static String	INFERRED
static String	KIND
static String	LANG
static char	LANGUAGE_TAG_LITERAL_PREFIX
static String	LITERAL
static String	NULL_CONTEXT_NATIVE
static char	NULL_CONTEXT_PREFIX
static char	PLAIN_LITERAL_PREFIX
static String	PREDICATE_PROP
static String	SEPARATOR
static String	TYPE
static char	TYPED_LITERAL_PREFIX
static String	URI
static char	URI_PREFIX
static String	VALUE

Fields inherited from class org.openrdf.sail.helpers.SailBase

connectionTimeOut, DEFAULT_CONNECTION_TIMEOUT, initializationLock, logger

Constructor Summary

GraphSail(T graph)
Create a new RDF store using the provided Blueprints graph.

GraphSail(T graph, String indexedPatterns)
Create a new RDF store using the provided Blueprints graph.

Method Summary

void	enforceUniqueStatements(boolean flag) Enables or disables enforcement of a unique statements policy, which ensures that no new statement will be added which is identical (in all of its subject, predicate, object and context) to an existing statement.
T	getBaseGraph()
org.openrdf.sail.NotifyingSailConnection	getConnectionInternal()
File	getDataDir()
org.openrdf.model.ValueFactory	getValueFactory()
void	initializeInternal()
boolean	isWritable()
void	setDataDir(File file)
void	shutDownInternal()
String	toString()
void	useVolatileStatements(boolean flag) Enables or disables the use of efficient, short-lived statements in the iterators returned by GraphSailConnection.getStatements() and GraphSailConnection.evaluate().

Methods inherited from class org.openrdf.sail.helpers.NotifyingSailBase

addSailChangedListener, getConnection, notifySailChanged, removeSailChangedListener

Methods inherited from class org.openrdf.sail.helpers.SailBase

connectionClosed, debugEnabled, initialize, isInitialized, shutDown

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.openrdf.sail.Sail

initialize, shutDown

Field Detail

SEPARATOR

public static final String SEPARATOR

See Also:

Constant Field Values

PREDICATE_PROP

public static final String PREDICATE_PROP

See Also:

Constant Field Values

CONTEXT_PROP

public static final String CONTEXT_PROP

See Also:

Constant Field Values

URI_PREFIX

public static final char URI_PREFIX

See Also:

Constant Field Values

BLANK_NODE_PREFIX

public static final char BLANK_NODE_PREFIX

See Also:

Constant Field Values

PLAIN_LITERAL_PREFIX

public static final char PLAIN_LITERAL_PREFIX

See Also:

Constant Field Values

TYPED_LITERAL_PREFIX

public static final char TYPED_LITERAL_PREFIX

See Also:

Constant Field Values

LANGUAGE_TAG_LITERAL_PREFIX

public static final char LANGUAGE_TAG_LITERAL_PREFIX

See Also:

Constant Field Values

NULL_CONTEXT_PREFIX

public static final char NULL_CONTEXT_PREFIX

See Also:

Constant Field Values

INDEX_PATTERN

public static final Pattern INDEX_PATTERN

BNODE

public static final String BNODE

See Also:

Constant Field Values

INFERRED

public static final String INFERRED

See Also:

Constant Field Values

KIND

public static final String KIND

See Also:

Constant Field Values

LANG

public static final String LANG

See Also:

Constant Field Values

LITERAL

public static final String LITERAL

See Also:

Constant Field Values

TYPE

public static final String TYPE

See Also:

Constant Field Values

URI

public static final String URI

See Also:

Constant Field Values

VALUE

public static final String VALUE

See Also:

Constant Field Values

NULL_CONTEXT_NATIVE

public static final String NULL_CONTEXT_NATIVE

See Also:

Constant Field Values

Constructor Detail

GraphSail

public GraphSail(T graph)

Create a new RDF store using the provided Blueprints graph. Default edge indices will be used.

Parameters:

graph - the storage layer. If the provided graph implements TransactionalGraph and is in manual transaction mode, then this Sail will also be transactional.

GraphSail

public GraphSail(T graph,
                 String indexedPatterns)

Create a new RDF store using the provided Blueprints graph. Additionally, create edge indices for the provided triple patterns (potentially speeding up certain queries, while increasing storage overhead).

Parameters:

graph - the storage layer. If the provided graph implements TransactionalGraph and is in manual transaction mode, then this Sail will also be transactional. Any vertices and edges in the graph should have been previously created with GraphSail.

indexedPatterns - a comma-delimited list of triple patterns for index-based statement matching. Only p,c are required, while the default patterns are p,c,pc.

Method Detail

getBaseGraph

public T getBaseGraph()

Specified by:

getBaseGraph in interface WrapperGraph<T extends KeyIndexableGraph>

setDataDir

public void setDataDir(File file)

Specified by:

setDataDir in interface org.openrdf.sail.Sail

Overrides:

setDataDir in class org.openrdf.sail.helpers.SailBase

getDataDir

public File getDataDir()

Specified by:

getDataDir in interface org.openrdf.sail.Sail

Overrides:

getDataDir in class org.openrdf.sail.helpers.SailBase

initializeInternal

public void initializeInternal()
                        throws org.openrdf.sail.SailException

Overrides:

initializeInternal in class org.openrdf.sail.helpers.SailBase

Throws:

org.openrdf.sail.SailException

shutDownInternal

public void shutDownInternal()
                      throws org.openrdf.sail.SailException

Specified by:

shutDownInternal in class org.openrdf.sail.helpers.SailBase

Throws:

org.openrdf.sail.SailException

isWritable

public boolean isWritable()
                   throws org.openrdf.sail.SailException

Specified by:

isWritable in interface org.openrdf.sail.Sail

Throws:

org.openrdf.sail.SailException

getConnectionInternal

public org.openrdf.sail.NotifyingSailConnection getConnectionInternal()
                                                               throws org.openrdf.sail.SailException

Overrides:

getConnectionInternal in class org.openrdf.sail.helpers.NotifyingSailBase

Throws:

org.openrdf.sail.SailException

getValueFactory

public org.openrdf.model.ValueFactory getValueFactory()

Specified by:

getValueFactory in interface org.openrdf.sail.Sail

useVolatileStatements

public void useVolatileStatements(boolean flag)

Enables or disables the use of efficient, short-lived statements in the iterators returned by GraphSailConnection.getStatements() and GraphSailConnection.evaluate(). This feature is disabled by default, and in typical usage scenarios, Java compiler optimization makes it superfluous. However, it potentially confers a performance advantage when a single thread consumes the iterator, inspecting and then immediately discarding each statement.

Parameters:

flag - whether to use volatile statements. When this method is called, only subsequently created iterators are affected.

enforceUniqueStatements

public void enforceUniqueStatements(boolean flag)

Enables or disables enforcement of a unique statements policy, which ensures that no new statement will be added which is identical (in all of its subject, predicate, object and context) to an existing statement. If enabled, this policy will first remove any existing statements identical to the to-be-added statement, before adding the latter statement.

Parameters:

flag - whether this policy should be enforced

toString

public String toString()

Overrides:

toString in class org.openrdf.sail.helpers.SailBase