org.apache.marmotta.ldpath.backend.linkeddata

Class LDCacheBackend

java.lang.Object

org.apache.marmotta.ldpath.backend.linkeddata.LDCacheBackend

All Implemented Interfaces:

NodeBackend<org.openrdf.model.Value>, RDFBackend<org.openrdf.model.Value>

public class LDCacheBackend
extends Object
implements RDFBackend<org.openrdf.model.Value>

A Linked Data backend with persistent caching of the retrieved data. All data is read and stored in the directory passed as constructor argument.

Author: Sebastian Schaffert

Constructor Summary

Constructors

Constructor and Description
LDCacheBackend()
LDCacheBackend(LDCache ldcache)

Method Summary

Methods

Modifier and Type	Method and Description
Boolean	booleanValue(org.openrdf.model.Value node) Return the boolean value of a literal node.
org.openrdf.model.Literal	createLiteral(String content) Create a literal node with the content passed as argument
org.openrdf.model.Literal	createLiteral(String content, Locale language, URI type) Create a literal node with the content passed as argument
org.openrdf.model.URI	createURI(String uri) Create a URI mode with the URI passed as argument
Date	dateTimeValue(org.openrdf.model.Value node) TODO
Date	dateValue(org.openrdf.model.Value node) TODO
protected String	debugType(org.openrdf.model.Value value) Prints the type (URI,bNode,literal) by inspecting the parsed Value to improve error messages and other loggings.
BigDecimal	decimalValue(org.openrdf.model.Value node) Return the decimal number of a literal node.
Double	doubleValue(org.openrdf.model.Value node) Return the double value of a literal node.
Float	floatValue(org.openrdf.model.Value node) Return the float value of a literal node.
Locale	getLiteralLanguage(org.openrdf.model.Value n) Return the language of the literal node passed as argument.
URI	getLiteralType(org.openrdf.model.Value n) Return the URI of the type of the literal node passed as argument.
ThreadPoolExecutor	getThreadPool() Deprecated. subject to be removed in the next release
BigInteger	integerValue(org.openrdf.model.Value node) Return the arbitrary length integer value of a literal node.
Integer	intValue(org.openrdf.model.Value node) Return the 32bit integer value of a literal node.
boolean	isBlank(org.openrdf.model.Value n) Test whether the node passed as argument is a blank node
boolean	isLiteral(org.openrdf.model.Value n) Test whether the node passed as argument is a literal
boolean	isURI(org.openrdf.model.Value n) Test whether the node passed as argument is a URI
Collection<org.openrdf.model.Value>	listObjects(org.openrdf.model.Value subject, org.openrdf.model.Value property) List the objects of triples in the triple store underlying this backend that have the subject and property given as argument.
Collection<org.openrdf.model.Value>	listSubjects(org.openrdf.model.Value property, org.openrdf.model.Value object) List the subjects of triples in the triple store underlying this backend that have the object and property given as argument.
Long	longValue(org.openrdf.model.Value node) Return the long value of a literal node.
String	stringValue(org.openrdf.model.Value value) Return the string value of a node.
boolean	supportsThreading() Deprecated. subject to be removed in the next release
Date	timeValue(org.openrdf.model.Value node) TODO

Methods inherited from class java.lang.Object

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

Constructor Detail

LDCacheBackend

public LDCacheBackend()

LDCacheBackend

public LDCacheBackend(LDCache ldcache)

Method Detail

isLiteral

public boolean isLiteral(org.openrdf.model.Value n)

Test whether the node passed as argument is a literal

Specified by:

isLiteral in interface NodeBackend<org.openrdf.model.Value>

Parameters:

n - the node to check

Returns:

true if the node is a literal

isURI

public boolean isURI(org.openrdf.model.Value n)

Test whether the node passed as argument is a URI

Specified by:

isURI in interface NodeBackend<org.openrdf.model.Value>

Parameters:

n - the node to check

Returns:

true if the node is a URI

isBlank

public boolean isBlank(org.openrdf.model.Value n)

Test whether the node passed as argument is a blank node

Specified by:

isBlank in interface NodeBackend<org.openrdf.model.Value>

Parameters:

n - the node to check

Returns:

true if the node is a blank node

getLiteralLanguage

public Locale getLiteralLanguage(org.openrdf.model.Value n)

Return the language of the literal node passed as argument.

Specified by:

getLiteralLanguage in interface NodeBackend<org.openrdf.model.Value>

Parameters:

n - the literal node for which to return the language

Returns:

a Locale representing the language of the literal, or null if the literal node has no language

Throws:

IllegalArgumentException - in case the node is no literal

getLiteralType

public URI getLiteralType(org.openrdf.model.Value n)

Return the URI of the type of the literal node passed as argument.

Specified by:

getLiteralType in interface NodeBackend<org.openrdf.model.Value>

Parameters:

n - the literal node for which to return the typer

Returns:

a URI representing the type of the literal content, or null if the literal is untyped

Throws:

IllegalArgumentException - in case the node is no literal

stringValue

public String stringValue(org.openrdf.model.Value value)

Return the string value of a node. For a literal, this will be the content, for a URI node it will be the URI itself, and for a blank node it will be the identifier of the node.

Specified by:

stringValue in interface NodeBackend<org.openrdf.model.Value>

Parameters:

value -

Returns:

decimalValue

public BigDecimal decimalValue(org.openrdf.model.Value node)

Description copied from interface: NodeBackend

Return the decimal number of a literal node. Depending on the backend implementing this method, the value can be retrieved directly or must be parsed from the string representation. The method can throw a NumberFormatException or ArithmeticException indicating that the value cannot be represented as decimal, and an IllegalArgumentException, indicating that the passed node is not a literal.

Specified by:

decimalValue in interface NodeBackend<org.openrdf.model.Value>

Parameters:

node - the literal node for which to return the xsd:decimal value

Returns:

long value of the literal node

integerValue

public BigInteger integerValue(org.openrdf.model.Value node)

Description copied from interface: NodeBackend

Return the arbitrary length integer value of a literal node. Depending on the backend implementing this method, the value can be retrieved directly or must be parsed from the string representation. The method can throw a NumberFormatException or ArithmeticException indicating that the value cannot be represented as integer, and an IllegalArgumentException, indicating that the passed node is not a literal.

Specified by:

integerValue in interface NodeBackend<org.openrdf.model.Value>

Parameters:

node - the literal node for which to return the xsd:integer value

Returns:

long value of the literal node

booleanValue

public Boolean booleanValue(org.openrdf.model.Value node)

Description copied from interface: NodeBackend

Return the boolean value of a literal node. Depending on the backend implementing this method, the value can be retrieved directly or must be parsed from the string representation. TODO: Define:

• Do we also support '0' '1', 'yes', 'no'; whats about case insensitive such as TRUE, False
• should we throw an RuntimeException of not an boolean value or return false as Boolean.parseBoolean(String)

Specified by:

booleanValue in interface NodeBackend<org.openrdf.model.Value>

Parameters:

node - the literal node for which to return the boolean value

Returns:

long value of the literal node

dateTimeValue

public Date dateTimeValue(org.openrdf.model.Value node)

Description copied from interface: NodeBackend

TODO

Specified by:

dateTimeValue in interface NodeBackend<org.openrdf.model.Value>

Parameters:

node - the literal node for which to return the dateTime value

Returns:

long value of the literal node

dateValue

public Date dateValue(org.openrdf.model.Value node)

Description copied from interface: NodeBackend

TODO

Specified by:

dateValue in interface NodeBackend<org.openrdf.model.Value>

Parameters:

node - the literal node for which to return the date value

Returns:

long value of the literal node

timeValue

public Date timeValue(org.openrdf.model.Value node)

Description copied from interface: NodeBackend

TODO

Specified by:

timeValue in interface NodeBackend<org.openrdf.model.Value>

Parameters:

node - the literal node for which to return the time value

Returns:

long value of the literal node

longValue

public Long longValue(org.openrdf.model.Value node)

Description copied from interface: NodeBackend

Return the long value of a literal node. Depending on the backend implementing this method, the value can be retrieved directly or must be parsed from the string representation. The method can throw a NumberFormatException or ArithmeticException indicating that the value cannot be represented as long, and an IllegalArgumentException, indicating that the passed node is not a literal

Specified by:

longValue in interface NodeBackend<org.openrdf.model.Value>

Parameters:

node - the literal node for which to return the long value

Returns:

long value of the literal node

doubleValue

public Double doubleValue(org.openrdf.model.Value node)

Description copied from interface: NodeBackend

Return the double value of a literal node. Depending on the backend implementing this method, the value can be retrieved directly or must be parsed from the string representation. The method can throw a NumberFormatException or ArithmeticException indicating that the value cannot be represented as double, and an IllegalArgumentException, indicating that the passed node is not a literal

Specified by:

doubleValue in interface NodeBackend<org.openrdf.model.Value>

Parameters:

node - the literal node for which to return the double value

Returns:

double value of the literal node

floatValue

public Float floatValue(org.openrdf.model.Value node)

Description copied from interface: NodeBackend

Return the float value of a literal node. Depending on the backend implementing this method, the value can be retrieved directly or must be parsed from the string representation. The method can throw a NumberFormatException or ArithmeticException indicating that the value cannot be represented as float, and an IllegalArgumentException, indicating that the passed node is not a literal

Specified by:

floatValue in interface NodeBackend<org.openrdf.model.Value>

Parameters:

node - the literal node for which to return the float value

Returns:

long value of the literal node

intValue

public Integer intValue(org.openrdf.model.Value node)

Description copied from interface: NodeBackend

Return the 32bit integer value of a literal node. Depending on the backend implementing this method, the value can be retrieved directly or must be parsed from the string representation. The method can throw a NumberFormatException or ArithmeticException indicating that the value cannot be represented as integer, and an IllegalArgumentException, indicating that the passed node is not a literal.

Note that this is restricted to 32bit singed integer values as defined by xsd:int and Integer. For bigger nuber one might want to use xsd:integer represented by BigInteger.

Specified by:

intValue in interface NodeBackend<org.openrdf.model.Value>

Parameters:

node - the literal node for which to return the Integer (xsd:int) value

Returns:

long value of the literal node

debugType

protected String debugType(org.openrdf.model.Value value)

Prints the type (URI,bNode,literal) by inspecting the parsed Value to improve error messages and other loggings. In case of literals also the literal type is printed

Parameters:

value - the value or null

Returns:

the type as string.

createLiteral

public org.openrdf.model.Literal createLiteral(String content)

Description copied from interface: NodeBackend

Create a literal node with the content passed as argument

Specified by:

createLiteral in interface NodeBackend<org.openrdf.model.Value>

Parameters:

content - string content to represent inside the literal

Returns:

a literal node in using the model used by this backend

createLiteral

public org.openrdf.model.Literal createLiteral(String content,
                                      Locale language,
                                      URI type)

Description copied from interface: NodeBackend

Create a literal node with the content passed as argument

Specified by:

createLiteral in interface NodeBackend<org.openrdf.model.Value>

Parameters:

content - string content to represent inside the literal

Returns:

a literal node in using the model used by this backend

createURI

public org.openrdf.model.URI createURI(String uri)

Description copied from interface: NodeBackend

Create a URI mode with the URI passed as argument

Specified by:

createURI in interface NodeBackend<org.openrdf.model.Value>

Parameters:

uri - URI of the resource to create

Returns:

a URI node using the model used by this backend

supportsThreading

public boolean supportsThreading()

Deprecated. subject to be removed in the next release

Specified by:

supportsThreading in interface RDFBackend<org.openrdf.model.Value>

getThreadPool

public ThreadPoolExecutor getThreadPool()

Deprecated. subject to be removed in the next release

Specified by:

getThreadPool in interface RDFBackend<org.openrdf.model.Value>

listObjects

public Collection<org.openrdf.model.Value> listObjects(org.openrdf.model.Value subject,
                                              org.openrdf.model.Value property)

List the objects of triples in the triple store underlying this backend that have the subject and property given as argument.

Specified by:

listObjects in interface RDFBackend<org.openrdf.model.Value>

Parameters:

subject - the subject of the triples to look for

property - the property of the triples to look for, null is interpreted as wildcard

Returns:

all objects of triples with matching subject and property

listSubjects

public Collection<org.openrdf.model.Value> listSubjects(org.openrdf.model.Value property,
                                               org.openrdf.model.Value object)

List the subjects of triples in the triple store underlying this backend that have the object and property given as argument.

Specified by:

listSubjects in interface RDFBackend<org.openrdf.model.Value>

Parameters:

property - the property of the triples to look for, null is interpreted as wildcard

object - the object of the triples to look for

Returns:

all subjects of triples with matching object and property

Throws:

UnsupportedOperationException - in case reverse selection is not supported (e.g. when querying Linked Data)