org.springframework.ldap.transaction.compensating.manager
Class ContextSourceTransactionManager

java.lang.Object
  org.springframework.transaction.support.AbstractPlatformTransactionManager
      org.springframework.ldap.transaction.compensating.manager.ContextSourceTransactionManager

All Implemented Interfaces:

Serializable, PlatformTransactionManager

public class ContextSourceTransactionManager
extends AbstractPlatformTransactionManager

TransactionManager for managing LDAP transactions. Since transactions are not supported in the LDAP protocol, this class and its collaborators aim to provide compensating transactions instead. Should a transaction need to be rolled back, this TransactionManager will try to restore the original state using information recorded prior to each operation. The operation where the original state is restored is called a compensating operation.

NOTE: The transactions provided by this TransactionManager are all client side and are by no means 'real' transactions, in the sense that we know them in the ordinary database world, e.g.:

• Should the transaction failure be caused by a network failure, there is no way whatsoever that this TransactionManager can restore the database state. In this case, all possibilities for rollback will be utterly lost.
• Transaction isolation is not provided, i.e. entries participating in a transaction for one client may very well participate in another transaction for another client at the same time. Should one of these transactions be rolled back, the outcome of this is undetermined, and may in the worst case result in total failure.

While the points above should be noted and considered, the compensating transaction approach will be perfectly sufficient for all but the most unfortunate of circumstances. Considering that there currently is a total absence of server-side transaction support in the LDAP world, being able to mark operations as transactional in the same way as for relational database operations is surely a step forward.

An LDAP transaction is tied to a ContextSource, to be supplied to the setContextSource(ContextSource) method. While the actual ContextSource used by the target LdapTemplate instance needs to be of the type TransactionAwareContextSourceProxy, the ContextSource supplied to this class should be the actual target ContextSource.

Using this TransactionManager along with TransactionAwareContextSourceProxy, all modifying operations (bind, unbind, rebind, rename, modifyAttributes) in a transaction will be intercepted. Each modification has its corresponding CompensatingTransactionOperationRecorder, which collects the information necessary to perform a rollback and produces a CompensatingTransactionOperationExecutor which is then used to execute the actual operation and is later called for performing the commit or rollback.

For several of the operations, performing a rollback is pretty straightforward. For example, in order to roll back a rename operation, it will only be required to rename the entry back to its original position. For other operations, however, it's a bit more complicated. An unbind operation is not possible to roll back by simply binding the entry back with the attributes retrieved from the original entry. It might not be possible to get all the information from the original entry. Consequently, the UnbindOperationExecutor will move the original entry to a temporary location in its performOperation() method. The commit() method will know that everything went well, so it will be OK to unbind the entry. The rollback operation will be to rename the entry back to its original location. The same behaviour is used for rebind() operations. The operation of calculating a temporary location for an entry is delegated to a TempEntryRenamingStrategy (default DefaultTempEntryRenamingStrategy), specified in setRenamingStrategy(TempEntryRenamingStrategy).

The actual work of this Transaction Manager is delegated to a ContextSourceTransactionManagerDelegate. This is because the exact same logic needs to be used if we want to wrap a JDBC and LDAP transaction in the same logical transaction.

Since:

1.2

Author:

Mattias Hellborg Arthursson

See Also:

ContextSourceAndDataSourceTransactionManager, ContextSourceTransactionManagerDelegate, DefaultCompensatingTransactionOperationManager, TempEntryRenamingStrategy, TransactionAwareContextSourceProxy, Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class org.springframework.transaction.support.AbstractPlatformTransactionManager

AbstractPlatformTransactionManager.SuspendedResourcesHolder

Field Summary

Fields inherited from class org.springframework.transaction.support.AbstractPlatformTransactionManager

logger, SYNCHRONIZATION_ALWAYS, SYNCHRONIZATION_NEVER, SYNCHRONIZATION_ON_ACTUAL_TRANSACTION

Constructor Summary

ContextSourceTransactionManager()

Method Summary

protected void	doBegin(Object transaction, TransactionDefinition definition)
protected void	doCleanupAfterCompletion(Object transaction)
protected void	doCommit(DefaultTransactionStatus status)
protected Object	doGetTransaction()
protected void	doRollback(DefaultTransactionStatus status)
ContextSource	getContextSource() Get the ContextSource.
void	setContextSource(ContextSource contextSource) Set the ContextSource.
void	setRenamingStrategy(TempEntryRenamingStrategy renamingStrategy) Set the TempEntryRenamingStrategy.

Methods inherited from class org.springframework.transaction.support.AbstractPlatformTransactionManager

commit, determineTimeout, doResume, doSetRollbackOnly, doSuspend, getDefaultTimeout, getTransaction, getTransactionSynchronization, invokeAfterCompletion, isExistingTransaction, isFailEarlyOnGlobalRollbackOnly, isGlobalRollbackOnParticipationFailure, isNestedTransactionAllowed, isRollbackOnCommitFailure, isValidateExistingTransaction, newTransactionStatus, prepareForCommit, prepareSynchronization, prepareTransactionStatus, registerAfterCompletionWithExistingTransaction, resume, rollback, setDefaultTimeout, setFailEarlyOnGlobalRollbackOnly, setGlobalRollbackOnParticipationFailure, setNestedTransactionAllowed, setRollbackOnCommitFailure, setTransactionSynchronization, setTransactionSynchronizationName, setValidateExistingTransaction, shouldCommitOnGlobalRollbackOnly, suspend, triggerBeforeCommit, triggerBeforeCompletion, useSavepointForNestedTransaction

Methods inherited from class java.lang.Object

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

Constructor Detail

ContextSourceTransactionManager

public ContextSourceTransactionManager()

Method Detail

doBegin

protected void doBegin(Object transaction,
                       TransactionDefinition definition)
                throws TransactionException

Specified by:

doBegin in class AbstractPlatformTransactionManager

Throws:

TransactionException

doCleanupAfterCompletion

protected void doCleanupAfterCompletion(Object transaction)

Overrides:

doCleanupAfterCompletion in class AbstractPlatformTransactionManager

doCommit

protected void doCommit(DefaultTransactionStatus status)
                 throws TransactionException

Specified by:

doCommit in class AbstractPlatformTransactionManager

Throws:

TransactionException

doGetTransaction

protected Object doGetTransaction()
                           throws TransactionException

Specified by:

doGetTransaction in class AbstractPlatformTransactionManager

Throws:

TransactionException

doRollback

protected void doRollback(DefaultTransactionStatus status)
                   throws TransactionException

Specified by:

doRollback in class AbstractPlatformTransactionManager

Throws:

TransactionException

getContextSource

public ContextSource getContextSource()

Get the ContextSource.

Returns:

the contextSource.

See Also:

ContextSourceTransactionManagerDelegate.getContextSource()

setContextSource

public void setContextSource(ContextSource contextSource)

Set the ContextSource.

Parameters:

contextSource - the ContextSource.

See Also:

ContextSourceTransactionManagerDelegate.setContextSource(ContextSource)

setRenamingStrategy

public void setRenamingStrategy(TempEntryRenamingStrategy renamingStrategy)

Set the TempEntryRenamingStrategy.

Parameters:

renamingStrategy - the Renaming Strategy.

See Also:

ContextSourceTransactionManagerDelegate.setRenamingStrategy(TempEntryRenamingStrategy)