net.fortytwo.linkeddata

Class LinkedDataCache

java.lang.Object

net.fortytwo.linkeddata.LinkedDataCache

public class LinkedDataCache
extends java.lang.Object

A manager for a dynamic set of RDF graphs collected from the Web. The cache uses configurable IRI dereferencers and RDFizers to fetch and translate documents, and connects to an RDF triple store which provides a unified view of the Web of Data.

Author:

Joshua Shinavier (http://fortytwo.net)

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	LinkedDataCache.DataStore
class	LinkedDataCache.SailInserter

Field Summary

Fields

Modifier and Type	Field and Description
static org.openrdf.model.IRI	CACHE_GRAPH
static org.openrdf.model.IRI	CACHE_MEMO
static org.openrdf.model.IRI	CACHE_REDIRECTSTO

Method Summary

Modifier and Type	Method and Description
void	clear()
void	close()
static LinkedDataCache	createDefault(org.openrdf.sail.Sail sail) Constructs a cache with the default settings, dereferencers, and rdfizers.
java.lang.String	getAcceptHeader()
boolean	getDereferenceContexts()
boolean	getDereferenceObjects()
boolean	getDereferencePredicates()
boolean	getDereferenceSubjects()
org.openrdf.sail.SailConnection	getSailConnection()
boolean	isAutoCommit()
CacheEntry.Status	peek(org.openrdf.model.IRI iri, org.openrdf.sail.SailConnection sc) Retrieves caching metadata for a IRI if it exists, but does not dereference the IRI or modify the cache.
CacheEntry.Status	retrieve(org.openrdf.model.IRI iri, org.openrdf.sail.SailConnection sc) Retrieves caching metadata for a URI, possibly dereferencing a document from the Web first.
void	setAutoCommit(boolean autoCommit)
void	setDataStore(LinkedDataCache.DataStore dataStore)
void	setDereferenceContexts(boolean flag)
void	setDereferenceObjects(boolean flag)
void	setDereferencePredicates(boolean flag)
void	setDereferenceSubjects(boolean flag)
void	setExpirationPolicy(CacheExpirationPolicy expirationPolicy)

Methods inherited from class java.lang.Object

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

Field Detail

CACHE_MEMO

public static final org.openrdf.model.IRI CACHE_MEMO

CACHE_REDIRECTSTO

public static final org.openrdf.model.IRI CACHE_REDIRECTSTO

CACHE_GRAPH

public static final org.openrdf.model.IRI CACHE_GRAPH

Method Detail

createDefault

public static LinkedDataCache createDefault(org.openrdf.sail.Sail sail)

Constructs a cache with the default settings, dereferencers, and rdfizers.

Parameters:

sail - the underlying triple store for the cache

Returns:

the default cache

clear

public void clear()

close

public void close()

getSailConnection

public org.openrdf.sail.SailConnection getSailConnection()

setDataStore

public void setDataStore(LinkedDataCache.DataStore dataStore)

getAcceptHeader

public java.lang.String getAcceptHeader()

Returns:

an HTTP "Accept" header which matches the cache's collection of rdfizers

peek

public CacheEntry.Status peek(org.openrdf.model.IRI iri,
                              org.openrdf.sail.SailConnection sc)
                       throws java.io.IOException

Retrieves caching metadata for a IRI if it exists, but does not dereference the IRI or modify the cache.

Parameters:

iri - the IRI to look up

sc - a connection to a Sail

Returns:

the current status of the URI, or null if it does not exist in the cache

Throws:

java.io.IOException

retrieve

public CacheEntry.Status retrieve(org.openrdf.model.IRI iri,
                                  org.openrdf.sail.SailConnection sc)
                           throws java.io.IOException

Retrieves caching metadata for a URI, possibly dereferencing a document from the Web first.

Parameters:

iri - the IRI to look up and possibly dereference

sc - a connection to a Sail

Returns:

the result of the dereferencing operation

Throws:

java.io.IOException

isAutoCommit

public boolean isAutoCommit()

Returns:

whether the cache commits to the triple store after each Web request (true by default)

setAutoCommit

public void setAutoCommit(boolean autoCommit)

Parameters:

autoCommit - whether the cache should commit to the triple store after each Web request (true by default)

setExpirationPolicy

public void setExpirationPolicy(CacheExpirationPolicy expirationPolicy)

Parameters:

expirationPolicy - the rule by which the cache determines whether a cache entry has expired. If an entry has expired, the cache will issue a new request in order to refresh it.

getDereferenceSubjects

public boolean getDereferenceSubjects()

setDereferenceSubjects

public void setDereferenceSubjects(boolean flag)

getDereferencePredicates

public boolean getDereferencePredicates()

setDereferencePredicates

public void setDereferencePredicates(boolean flag)

getDereferenceObjects

public boolean getDereferenceObjects()

setDereferenceObjects

public void setDereferenceObjects(boolean flag)

getDereferenceContexts

public boolean getDereferenceContexts()

setDereferenceContexts

public void setDereferenceContexts(boolean flag)