org.openrdf.sail.base

Interface SailDataset

All Superinterfaces:

SailClosable

public interface SailDataset
extends SailClosable

A state of an SailSource at a point in time that will remain consistent until close() is called. The life cycle follows that of a read operation.

Author:

James Leigh

Method Summary

Modifier and Type	Method and Description
void	close() Called when this SailDataset is no longer is used, such as when a read operation is complete.
CloseableIteration<? extends Resource,SailException>	getContextIDs() Returns the set of all unique context identifiers that are used to store statements.
String	getNamespace(String prefix) Gets the namespace that is associated with the specified prefix, if any.
CloseableIteration<? extends Namespace,SailException>	getNamespaces() Gets the namespaces relevant to the data contained in this object.
CloseableIteration<? extends Statement,SailException>	getStatements(Resource subj, URI pred, Value obj, Resource... contexts) Gets all statements that have a specific subject, predicate and/or object.

Method Detail

close

void close()
    throws SailException

Called when this SailDataset is no longer is used, such as when a read operation is complete. An isolation level compatible with IsolationLevels.SNAPSHOT will ensure the state of this SailDataset dose not change between the first call to this object until #release() is called.

Specified by:

close in interface SailClosable

Throws:

SailException - if this resource cannot be closed

getNamespaces

CloseableIteration<? extends Namespace,SailException> getNamespaces()
                                                             throws SailException

Gets the namespaces relevant to the data contained in this object.

Returns:

An iterator over the relevant namespaces, should not contain any duplicates.

Throws:

SailException - If this object encountered an error or unexpected situation internally.

getNamespace

String getNamespace(String prefix)
             throws SailException

Gets the namespace that is associated with the specified prefix, if any.

Parameters:

prefix - A namespace prefix, or an empty string in case of the default namespace.

Returns:

The namespace name that is associated with the specified prefix, or null if there is no such namespace.

Throws:

SailException - If this object encountered an error or unexpected situation internally.

NullPointerException - In case prefix is null.

getContextIDs

CloseableIteration<? extends Resource,SailException> getContextIDs()
                                                            throws SailException

Returns the set of all unique context identifiers that are used to store statements.

Returns:

An iterator over the context identifiers, should not contain any duplicates.

Throws:

SailException

getStatements

CloseableIteration<? extends Statement,SailException> getStatements(Resource subj,
                                                                    URI pred,
                                                                    Value obj,
                                                                    Resource... contexts)
                                                             throws SailException

Gets all statements that have a specific subject, predicate and/or object. All three parameters may be null to indicate wildcards. Optionally a (set of) context(s) may be specified in which case the result will be restricted to statements matching one or more of the specified contexts.

Parameters:

subj - A Resource specifying the subject, or null for a wildcard.

pred - A URI specifying the predicate, or null for a wildcard.

obj - A Value specifying the object, or null for a wildcard.

contexts - The context(s) to get the statements from. Note that this parameter is a vararg and as such is optional. If no contexts are supplied the method operates on all contexts.

Returns:

An iterator over the relevant statements.

Throws:

SailException - If the triple source failed to get the statements.