org.lacibus.backingstore

Class FileSourceConnector

java.lang.Object

org.lacibus.triplesource.SourceConnector

org.lacibus.backingstore.FileSourceConnector

All Implemented Interfaces:

java.io.Serializable

public class FileSourceConnector
extends SourceConnector

An instance of this class is a connector to a file backing store that acts as a source of items and triples. The client of the connector must be the owner of the source.

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class org.lacibus.triplesource.SourceConnector

SourceConnector.IdAndTrans

Field Summary

Fields inherited from class org.lacibus.triplesource.SourceConnector

adminLevelItemNr, adminLevelTripleNr, sourceItemNr

Constructor Summary

Constructors

Constructor and Description
FileSourceConnector(SourceConnectorClient client, long sourceNr, java.io.File localDir, java.io.File specFile, Logger logger) Construct a new file source connector.

Method Summary

Modifier and Type	Method and Description
SourceConnector.IdAndTrans	addItem(Id onlyReadLevelId, Id readOrWriteLevelId) Add an item
void	close() Close the source connector
void	create() Create the source.
StoredTriple	createTriple(Item subject, Item verb, Datum object, Transaction trans) Create a triple
void	endTransaction(Transaction trans) End a transaction.
Datum	getBinaryTripleObject(long tripleNr) Get a stored triple's binary object
long	getHighestItemNr()
long	getHighestTripleNr()
long	getSourceNr()
java.lang.Exception	getTerminator() Implements the getTerminator() method of SourceConnector
Datum	getTextTripleObject(long tripleNr) Get a stored triple's text object
boolean	isCompleted(long transSeq) Determine whether a transaction has completed
boolean	isOwner()
void	load() Load items and triples into a triple store from the connector, but without adding the items to the triple store's index.
void	loadItem(long itemNr, long readLevelSourceNr, long readLevelItemNr, long writeLevelSourceNr, long writeLevelItemNr, int storeRef) Load an item from the backing store
void	loadTriple(long tripleNr, long subjectItemNr, long verbSourceNr, long verbItemNr, Datum object, int storeRef) Load a triple from the backing store
void	removeItem(long itemNr, Transaction trans) Remove an item from the source
void	removeTriple(long tripleNr, Transaction trans) Note that a triple is removed from the source.
StoredTriple	replaceTriple(Triple triple, Datum newObject, Transaction trans) Replace a triple in the source by a new triple with the same subject and verb, but with a new object and a new numeric identifier
void	simulateIoError() Simulate an I/O error for testing purposes
boolean	sourceExists() Determine whether the source exists or must be created.
Transaction	startTransaction() Start a transaction.
void	updateItem(long itemNr, Id onlyReadLevelId, Id readOrWriteLevelId, Transaction trans) Update an item in the source

Methods inherited from class org.lacibus.triplesource.SourceConnector

addSourceItem, createSourceTriple, endSourceTransaction, getClient, getLocalDir, getSourceBinaryTripleObject, getSourceTextTripleObject, getSpecFile, getSpecFilePath, isDomainSourceNr, isInstallationSourceNr, isOperational, isRegisteredSourceNr, log, makeOperational, removeSourceItem, removeSourceTriple, replaceSourceTriple, startSourceTransaction, stopOperation, updateSourceItem

Methods inherited from class java.lang.Object

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

Constructor Detail

FileSourceConnector

public FileSourceConnector(SourceConnectorClient client,
                           long sourceNr,
                           java.io.File localDir,
                           java.io.File specFile,
                           Logger logger)
                    throws SourceConnectorException

Construct a new file source connector.

A file source connector can only connect to a private source

Parameters:

directory - the directory containing the the file backing store that is the source of items and triples

sourceNr - the numeric identifier of the source

Throws:

SourceConnectorStateException

SourceConnectorException

Method Detail

getSourceNr

public long getSourceNr()

Overrides:

getSourceNr in class SourceConnector

Returns:

the numeric identifier of the source that the connector is connected to

sourceExists

public boolean sourceExists()
                     throws SourceConnectorException

Description copied from class: SourceConnector

Determine whether the source exists or must be created. If this method returns true, then the caller should assume that the source has been created. If it returns false, then the caller should create it.

Specified by:

sourceExists in class SourceConnector

Returns:

true if the source exists, or creation of the source has at least been started.

Throws:

SourceConnectorException

create

public void create()
            throws SourceConnectorException,
                   TripleStoreNonFatalException

Description copied from class: SourceConnector

Create the source.

A new source is created.

A source must be created, or loaded, but not both, before it can be used.

A source is created with a source item and a source administration access level. The only-read level of the source item is the lowest access level, and its read-or-write level is the highest access level.The only-read level of the source administration access level is the lowest access level, and it is its own read-or-write level.

Specified by:

create in class SourceConnector

Throws:

SourceConnectorException

TripleStoreNonFatalException

load

public void load()
          throws SourceConnectorException

Description copied from class: SourceConnector

Load items and triples into a triple store from the connector, but without adding the items to the triple store's index.

Invoked by the loadFromSource() method to apply a set of deltas that add items and triples in the source to the invoking triple store. This part of the load process is specific to the source. The subsequent part, in which the loaded items are indexed, is handled by the loadFromSource() method.

Note that the deltas may contain deletions as well as additions, and must be applied in order. This implies that the connector must apply deltas adding the items referenced by a triple before applying the delta that adds the triple. However, triples setting access level superiority permissions can be loaded before the triples defining the access levels concerned.

A source must be created, or loaded, but not both, before it can be used.

Specified by:

load in class SourceConnector

Throws:

SourceConnectorException

isOwner

public boolean isOwner()

Overrides:

isOwner in class SourceConnector

Returns:

whether the source connector is connecting the source's owner to the source

close

public void close()

Description copied from class: SourceConnector

Close the source connector

Specified by:

close in class SourceConnector

simulateIoError

public void simulateIoError()

Description copied from class: SourceConnector

Simulate an I/O error for testing purposes

Specified by:

simulateIoError in class SourceConnector

getTerminator

public java.lang.Exception getTerminator()

Implements the getTerminator() method of SourceConnector

Specified by:

getTerminator in class SourceConnector

Returns:

the Exception that aborted operation

startTransaction

public Transaction startTransaction()
                             throws SourceConnectorException

Start a transaction.

Specified by:

startTransaction in class SourceConnector

Returns:

a new, unique, transaction

Throws:

FileSourceConnectorException

SourceConnectorException

endTransaction

public void endTransaction(Transaction trans)
                    throws SourceConnectorException

End a transaction.

All data written by the transaction is stored on disc, and the transaction is noted as completed.

No check is made that the transaction is not already complete. The results of invoking this method twice for the same transaction are indeterminate.

Specified by:

endTransaction in class SourceConnector

Parameters:

trans - a transaction to be ended

Throws:

SourceConnectorException

isCompleted

public boolean isCompleted(long transSeq)
                    throws SourceConnectorException

Determine whether a transaction has completed

Parameters:

transSeq - a transaction sequence number

Returns:

true if the transaction with the given sequence number has completed, false otherwise

Throws:

FileSourceConnectorException

SourceConnectorException

getHighestItemNr

public long getHighestItemNr()

Returns:

the highest identifier of any item that has been stored

getHighestTripleNr

public long getHighestTripleNr()

Returns:

the highest identifier of any triple that has been stored

loadItem

public void loadItem(long itemNr,
                     long readLevelSourceNr,
                     long readLevelItemNr,
                     long writeLevelSourceNr,
                     long writeLevelItemNr,
                     int storeRef)
              throws org.lacibus.backingstore.BackingStoreClientException

Load an item from the backing store

Parameters:

itemNr - the numeric identifier of the item in its source

readLevelSourceNr - the numeric identifier of the source of the only-read access level of the item

readLevelItemNr - the numeric identifier in its source of the only-read access level of the item

writeLevelSourceNr - the numeric identifier of the source of the read-or-write access level of the item

writeLevelItemNr - the numeric identifier in its source of the read-or-write access level of the item

storeRef - a reference to the item in the backing store

Throws:

BackingStoreClientException

loadTriple

public void loadTriple(long tripleNr,
                       long subjectItemNr,
                       long verbSourceNr,
                       long verbItemNr,
                       Datum object,
                       int storeRef)
                throws org.lacibus.backingstore.BackingStoreClientException

Load a triple from the backing store

Parameters:

tripleNr - the numeric identifier of the triple in its source

subjectItemNr - the numeric identifier of the subject of the triple in its source

verbSourceNr - the numeric identifier of the source of the verb of the triple

verbItemNr - the numeric identifier of the verb of the triple in its source

object - the object of the triple

storeRef - a reference to the triple in the backing store

Throws:

BackingStoreClientException

addItem

public SourceConnector.IdAndTrans addItem(Id onlyReadLevelId,
                                          Id readOrWriteLevelId)
                                   throws SourceConnectorException

Description copied from class: SourceConnector

Add an item

Specified by:

addItem in class SourceConnector

Parameters:

onlyReadLevelId - the identifier of the item representing the only-read access level that the item is to have

readOrWriteLevelId - the identifier of the item representing the read-or-write access level that the item is to have

Returns:

a numeric item identifier and transaction. The identifier is a newly-assigned numeric identifier that identifies a new item that has been added to the source. The transaction is a newly started transaction whose first operation is the addition of the item.

Throws:

SourceConnectorException

updateItem

public void updateItem(long itemNr,
                       Id onlyReadLevelId,
                       Id readOrWriteLevelId,
                       Transaction trans)
                throws SourceConnectorException

Description copied from class: SourceConnector

Update an item in the source

Specified by:

updateItem in class SourceConnector

Parameters:

itemNr - the numeric identifier of the item in the source

onlyReadLevelId - the identifier of the item representing the only-read access level that the item is to have

readOrWriteLevelId - the identifier of the item representing the read-or-write access level that the item is to have

trans - the transaction of which this operation is a part

Throws:

SourceConnectorException

removeItem

public void removeItem(long itemNr,
                       Transaction trans)
                throws SourceConnectorException

Description copied from class: SourceConnector

Remove an item from the source

Specified by:

removeItem in class SourceConnector

Parameters:

itemNr - the numeric identifier of the item in the source

trans - the transaction of which this operation is a part

Throws:

SourceConnectorException

createTriple

public StoredTriple createTriple(Item subject,
                                 Item verb,
                                 Datum object,
                                 Transaction trans)
                          throws SourceConnectorException,
                                 TripleStoreNonFatalException

Description copied from class: SourceConnector

Create a triple

Specified by:

createTriple in class SourceConnector

Parameters:

subject - the triple's subject

verb - the triple's verb

object - the triple's object

trans - the transaction of which this operation is a part

Returns:

the newly-created triple

Throws:

SourceConnectorException

TripleStoreNonFatalException

replaceTriple

public StoredTriple replaceTriple(Triple triple,
                                  Datum newObject,
                                  Transaction trans)
                           throws SourceConnectorException,
                                  TripleStoreNonFatalException

Description copied from class: SourceConnector

Replace a triple in the source by a new triple with the same subject and verb, but with a new object and a new numeric identifier

Specified by:

replaceTriple in class SourceConnector

Parameters:

triple - the triple to be replaced

newObject - the triple's new object

trans - the transaction of which this operation is a part

Returns:

a new triple, with the previous subject and verb, the new object, and a new numeric identifier, or null if the triple can not be found

Throws:

SourceConnectorException

TripleStoreNonFatalException

removeTriple

public void removeTriple(long tripleNr,
                         Transaction trans)
                  throws SourceConnectorException

Description copied from class: SourceConnector

Note that a triple is removed from the source. The triple's underlying resources (for example, a file containing its object) are not deleted until the end of the transaction, so that the triple can be reinstated if the transaction does not complete.

Specified by:

removeTriple in class SourceConnector

Parameters:

tripleNr - the numeric identifier within the source of the triple to be removed

trans - the transaction of which this operation is a part

Throws:

SourceConnectorException

getTextTripleObject

public Datum getTextTripleObject(long tripleNr)
                          throws SourceConnectorException,
                                 TripleStoreNonFatalException

Description copied from class: SourceConnector

Get a stored triple's text object

Specified by:

getTextTripleObject in class SourceConnector

Parameters:

tripleNr - the numeric identifier in its source of a stored triple

Returns:

the triple's object

Throws:

SourceConnectorException

TripleStoreNonFatalException

getBinaryTripleObject

public Datum getBinaryTripleObject(long tripleNr)
                            throws SourceConnectorException,
                                   TripleStoreNonFatalException

Description copied from class: SourceConnector

Get a stored triple's binary object

Specified by:

getBinaryTripleObject in class SourceConnector

Parameters:

tripleNr - the numeric identifier in its source of a stored triple

Returns:

the triple's object

Throws:

SourceConnectorException

TripleStoreNonFatalException