helma.objectmodel.dom
Class XmlDatabase

java.lang.Object
  helma.objectmodel.dom.XmlDatabase

All Implemented Interfaces:

IDatabase

public final class XmlDatabase
extends java.lang.Object
implements IDatabase

A simple XML-database

Field Summary

protected Application	app
protected java.io.File	dbHomeDir
protected java.lang.String	encoding
protected XmlIDGenerator	idgen
protected NodeManager	nmgr

Constructor Summary

XmlDatabase()

Method Summary

void	abortTransaction(ITransaction txn) Abort the given transaction
ITransaction	beginTransaction() Start a new transaction.
void	commitTransaction(ITransaction txn) committ the given transaction, makint its changes persistent
void	deleteNode(ITransaction txn, java.lang.String kstr) Marks an element from the database as deleted
java.lang.String	getEncoding() get the file encoding used by this database
XmlIDGenerator	getIDGenerator(ITransaction txn) Get the id-generator for this database.
INode	getNode(ITransaction txn, java.lang.String kstr) Retrieves a Node from the database.
void	init(java.io.File dbHome, Application app) Initializes the database from an application.
void	insertNode(ITransaction txn, java.lang.String kstr, INode node) Save a node with the given key.
java.lang.String	nextID() Get the id for the next new object to be stored.
void	saveIDGenerator(ITransaction txn) Write the id-generator to file.
void	setEncoding(java.lang.String encoding) set the file encoding to use
void	shutdown() Shut down the database
void	updateNode(ITransaction txn, java.lang.String kstr, INode node) Update a node with the given key.

Methods inherited from class java.lang.Object

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

Field Detail

dbHomeDir

protected java.io.File dbHomeDir

app

protected Application app

nmgr

protected NodeManager nmgr

idgen

protected XmlIDGenerator idgen

encoding

protected java.lang.String encoding

Constructor Detail

XmlDatabase

public XmlDatabase()

Method Detail

init

public void init(java.io.File dbHome,
                 Application app)
          throws DatabaseException

Initializes the database from an application.

Specified by:

init in interface IDatabase

Parameters:

app -

Throws:

DatabaseException

shutdown

public void shutdown()

Shut down the database

Specified by:

shutdown in interface IDatabase

beginTransaction

public ITransaction beginTransaction()
                              throws DatabaseException

Start a new transaction.

Specified by:

beginTransaction in interface IDatabase

Returns:

the new tranaction object

Throws:

DatabaseException

commitTransaction

public void commitTransaction(ITransaction txn)
                       throws DatabaseException

committ the given transaction, makint its changes persistent

Specified by:

commitTransaction in interface IDatabase

Parameters:

txn -

Throws:

DatabaseException

abortTransaction

public void abortTransaction(ITransaction txn)
                      throws DatabaseException

Abort the given transaction

Specified by:

abortTransaction in interface IDatabase

Parameters:

txn -

Throws:

DatabaseException

nextID

public java.lang.String nextID()
                        throws ObjectNotFoundException

Get the id for the next new object to be stored.

Specified by:

nextID in interface IDatabase

Returns:

the id for the next new object to be stored

Throws:

ObjectNotFoundException

getIDGenerator

public XmlIDGenerator getIDGenerator(ITransaction txn)
                              throws ObjectNotFoundException

Get the id-generator for this database.

Parameters:

txn -

Returns:

the id-generator for this database

Throws:

ObjectNotFoundException

saveIDGenerator

public void saveIDGenerator(ITransaction txn)
                     throws java.io.IOException

Write the id-generator to file.

Parameters:

txn -

Throws:

java.io.IOException

getNode

public INode getNode(ITransaction txn,
                     java.lang.String kstr)
              throws java.io.IOException,
                     ObjectNotFoundException

Retrieves a Node from the database.

Specified by:

getNode in interface IDatabase

Parameters:

txn - the current transaction

kstr - the key

Returns:

the object associated with the given key

Throws:

java.io.IOException - if an I/O error occurred loading the object.

ObjectNotFoundException - if no object is stored by this key.

insertNode

public void insertNode(ITransaction txn,
                       java.lang.String kstr,
                       INode node)
                throws java.io.IOException

Save a node with the given key. Writes the node to a temporary file which is copied to its final name when the transaction is committed.

Specified by:

insertNode in interface IDatabase

Parameters:

txn -

kstr -

node -

Throws:

java.io.IOException

updateNode

public void updateNode(ITransaction txn,
                       java.lang.String kstr,
                       INode node)
                throws java.io.IOException

Update a node with the given key. Writes the node to a temporary file which is copied to its final name when the transaction is committed.

Specified by:

updateNode in interface IDatabase

Parameters:

txn -

kstr -

node -

Throws:

java.io.IOException

deleteNode

public void deleteNode(ITransaction txn,
                       java.lang.String kstr)
                throws java.io.IOException

Marks an element from the database as deleted

Specified by:

deleteNode in interface IDatabase

Parameters:

txn -

kstr -

Throws:

java.io.IOException

setEncoding

public void setEncoding(java.lang.String encoding)

set the file encoding to use

Parameters:

encoding - the database's file encoding

getEncoding

public java.lang.String getEncoding()

get the file encoding used by this database

Returns:

the file encoding used by this database