org.springframework.orm.hibernate3
Class HibernateTransactionManager

java.lang.Object
  org.springframework.transaction.support.AbstractPlatformTransactionManager
      org.springframework.orm.hibernate3.HibernateTransactionManager

All Implemented Interfaces:

Serializable, BeanFactoryAware, InitializingBean, PlatformTransactionManager, ResourceTransactionManager

public class HibernateTransactionManager
extends AbstractPlatformTransactionManager
implements ResourceTransactionManager, BeanFactoryAware, InitializingBean

PlatformTransactionManager implementation for a single Hibernate SessionFactory. Binds a Hibernate Session from the specified factory to the thread, potentially allowing for one thread-bound Session per factory. SessionFactoryUtils and HibernateTemplate are aware of thread-bound Sessions and participate in such transactions automatically. Using either of those or going through SessionFactory.getCurrentSession() is required for Hibernate access code that needs to support this transaction handling mechanism.

Supports custom isolation levels, and timeouts that get applied as Hibernate transaction timeouts (on Hibernate 3.1+) or as appropriate query timeouts (on Hibernate 3.0, when using HibernateTemplate).

This transaction manager is appropriate for applications that use a single Hibernate SessionFactory for transactional data access, but it also supports direct DataSource access within a transaction (i.e. plain JDBC code working with the same DataSource). This allows for mixing services which access Hibernate and services which use plain JDBC (without being aware of Hibernate)! Application code needs to stick to the same simple Connection lookup pattern as with DataSourceTransactionManager (i.e. DataSourceUtils.getConnection(javax.sql.DataSource) or going through a TransactionAwareDataSourceProxy).

Note: To be able to register a DataSource's Connection for plain JDBC code, this instance needs to be aware of the DataSource (setDataSource(javax.sql.DataSource)). The given DataSource should obviously match the one used by the given SessionFactory. To achieve this, configure both to the same JNDI DataSource, or preferably create the SessionFactory with LocalSessionFactoryBean and a local DataSource (which will be autodetected by this transaction manager).

JTA (usually through JtaTransactionManager) is necessary for accessing multiple transactional resources within the same transaction. The DataSource that Hibernate uses needs to be JTA-enabled in such a scenario (see container setup). Normally, JTA setup for Hibernate is somewhat container-specific due to the JTA TransactionManager lookup, required for proper transactional handling of the SessionFactory-level read-write cache.

Fortunately, there is an easier way with Spring: SessionFactoryUtils (and thus HibernateTemplate) registers synchronizations with Spring's TransactionSynchronizationManager (as used by JtaTransactionManager), for proper after-completion callbacks. Therefore, as long as Spring's JtaTransactionManager drives the JTA transactions, Hibernate does not require any special configuration for proper JTA participation. Note that there are special restrictions with EJB CMT and restrictive JTA subsystems: See JtaTransactionManager's javadoc for details.

On JDBC 3.0, this transaction manager supports nested transactions via JDBC 3.0 Savepoints. The AbstractPlatformTransactionManager.setNestedTransactionAllowed(boolean) "nestedTransactionAllowed"} flag defaults to "false", though, as nested transactions will just apply to the JDBC Connection, not to the Hibernate Session and its cached objects. You can manually set the flag to "true" if you want to use nested transactions for JDBC access code which participates in Hibernate transactions (provided that your JDBC driver supports Savepoints). Note that Hibernate itself does not support nested transactions! Hence, do not expect Hibernate access code to semantically participate in a nested transaction.

Requires Hibernate 3.0.3 or later. As of Spring 2.0, this transaction manager autodetects Hibernate 3.1 and uses its advanced timeout functionality, while remaining compatible with Hibernate 3.0 as well. Running against Hibernate 3.1.3+ is recommended, unless you need to remain compatible with JDK 1.3. (Note that Hibernate 3.1+ only runs on JDK 1.4+!)

Since:

1.2

Author:

Juergen Hoeller

See Also:

setSessionFactory(org.hibernate.SessionFactory), setDataSource(javax.sql.DataSource), LocalSessionFactoryBean, SessionFactoryUtils.getSession(org.hibernate.SessionFactory, boolean), SessionFactoryUtils.applyTransactionTimeout(org.hibernate.Query, org.hibernate.SessionFactory), SessionFactoryUtils.releaseSession(org.hibernate.Session, org.hibernate.SessionFactory), HibernateTemplate, SessionFactory.getCurrentSession(), DataSourceUtils.getConnection(javax.sql.DataSource), DataSourceUtils.applyTransactionTimeout(java.sql.Statement, javax.sql.DataSource), DataSourceUtils.releaseConnection(java.sql.Connection, javax.sql.DataSource), JdbcTemplate, DataSourceTransactionManager, JtaTransactionManager, Serialized Form

Field Summary

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

logger, SYNCHRONIZATION_ALWAYS, SYNCHRONIZATION_NEVER, SYNCHRONIZATION_ON_ACTUAL_TRANSACTION

Constructor Summary

HibernateTransactionManager()
Create a new HibernateTransactionManager instance.

HibernateTransactionManager(SessionFactory sessionFactory)
Create a new HibernateTransactionManager instance.

Method Summary

void	afterPropertiesSet() Invoked by a BeanFactory after it has set all bean properties supplied (and satisfied BeanFactoryAware and ApplicationContextAware).
protected DataAccessException	convertHibernateAccessException(HibernateException ex) Convert the given HibernateException to an appropriate exception from the org.springframework.dao hierarchy.
protected DataAccessException	convertJdbcAccessException(JDBCException ex, SQLExceptionTranslator translator) Convert the given Hibernate JDBCException to an appropriate exception from the org.springframework.dao hierarchy, using the given SQLExceptionTranslator.
protected void	doBegin(Object transaction, TransactionDefinition definition) Begin a new transaction with semantics according to the given transaction definition.
protected void	doCleanupAfterCompletion(Object transaction) Cleanup resources after transaction completion.
protected void	doCommit(DefaultTransactionStatus status) Perform an actual commit of the given transaction.
protected Object	doGetTransaction() Return a transaction object for the current transaction state.
protected void	doResume(Object transaction, Object suspendedResources) Resume the resources of the current transaction.
protected void	doRollback(DefaultTransactionStatus status) Perform an actual rollback of the given transaction.
protected void	doSetRollbackOnly(DefaultTransactionStatus status) Set the given transaction rollback-only.
protected Object	doSuspend(Object transaction) Suspend the resources of the current transaction.
DataSource	getDataSource() Return the JDBC DataSource that this instance manages transactions for.
protected SQLExceptionTranslator	getDefaultJdbcExceptionTranslator() Obtain a default SQLExceptionTranslator, lazily creating it if necessary.
Interceptor	getEntityInterceptor() Return the current Hibernate entity interceptor, or null if none.
SQLExceptionTranslator	getJdbcExceptionTranslator() Return the JDBC exception translator for this transaction manager, if any.
Object	getResourceFactory() Return the resource factory that this transaction manager operates on, e.g. a JDBC DataSource or a JMS ConnectionFactory.
SessionFactory	getSessionFactory() Return the SessionFactory that this instance should manage transactions for.
protected boolean	isExistingTransaction(Object transaction) Check if the given transaction object indicates an existing transaction (that is, a transaction which has already started).
protected boolean	isSameConnectionForEntireSession(Session session) Return whether the given Hibernate Session will always hold the same JDBC Connection.
void	setAutodetectDataSource(boolean autodetectDataSource) Set whether to autodetect a JDBC DataSource used by the Hibernate SessionFactory, if set via LocalSessionFactoryBean's setDataSource.
void	setBeanFactory(BeanFactory beanFactory) The bean factory just needs to be known for resolving entity interceptor bean names.
void	setDataSource(DataSource dataSource) Set the JDBC DataSource that this instance should manage transactions for.
void	setEntityInterceptor(Interceptor entityInterceptor) Set a Hibernate entity interceptor that allows to inspect and change property values before writing to and reading from the database.
void	setEntityInterceptorBeanName(String entityInterceptorBeanName) Set the bean name of a Hibernate entity interceptor that allows to inspect and change property values before writing to and reading from the database.
void	setJdbcExceptionTranslator(SQLExceptionTranslator jdbcExceptionTranslator) Set the JDBC exception translator for this transaction manager.
void	setPrepareConnection(boolean prepareConnection) Set whether to prepare the underlying JDBC Connection of a transactional Hibernate Session, that is, whether to apply a transaction-specific isolation level and/or the transaction's read-only flag to the underlying JDBC Connection.
void	setSessionFactory(SessionFactory sessionFactory) Set the SessionFactory that this instance should manage transactions for.

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

commit, determineTimeout, getDefaultTimeout, getTransaction, getTransactionSynchronization, invokeAfterCompletion, isFailEarlyOnGlobalRollbackOnly, isGlobalRollbackOnParticipationFailure, isNestedTransactionAllowed, isRollbackOnCommitFailure, newTransactionStatus, registerAfterCompletionWithExistingTransaction, resume, rollback, setDefaultTimeout, setFailEarlyOnGlobalRollbackOnly, setGlobalRollbackOnParticipationFailure, setNestedTransactionAllowed, setRollbackOnCommitFailure, setTransactionSynchronization, setTransactionSynchronizationName, shouldCommitOnGlobalRollbackOnly, suspend, triggerBeforeCommit, triggerBeforeCompletion, useSavepointForNestedTransaction

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.springframework.transaction.PlatformTransactionManager

commit, getTransaction, rollback

Constructor Detail

HibernateTransactionManager

public HibernateTransactionManager()

Create a new HibernateTransactionManager instance. A SessionFactory has to be set to be able to use it.

See Also:

setSessionFactory(org.hibernate.SessionFactory)

HibernateTransactionManager

public HibernateTransactionManager(SessionFactory sessionFactory)

Create a new HibernateTransactionManager instance.

Parameters:

sessionFactory - SessionFactory to manage transactions for

Method Detail

setSessionFactory

public void setSessionFactory(SessionFactory sessionFactory)

Set the SessionFactory that this instance should manage transactions for.

getSessionFactory

public SessionFactory getSessionFactory()

Return the SessionFactory that this instance should manage transactions for.

setDataSource

public void setDataSource(DataSource dataSource)

Set the JDBC DataSource that this instance should manage transactions for. The DataSource should match the one used by the Hibernate SessionFactory: for example, you could specify the same JNDI DataSource for both.

If the SessionFactory was configured with LocalDataSourceConnectionProvider, i.e. by Spring's LocalSessionFactoryBean with a specified "dataSource", the DataSource will be auto-detected: You can still explictly specify the DataSource, but you don't need to in this case.

A transactional JDBC Connection for this DataSource will be provided to application code accessing this DataSource directly via DataSourceUtils or JdbcTemplate. The Connection will be taken from the Hibernate Session.

The DataSource specified here should be the target DataSource to manage transactions for, not a TransactionAwareDataSourceProxy. Only data access code may work with TransactionAwareDataSourceProxy, while the transaction manager needs to work on the underlying target DataSource. If there's nevertheless a TransactionAwareDataSourceProxy passed in, it will be unwrapped to extract its target DataSource.

See Also:

setAutodetectDataSource(boolean), LocalDataSourceConnectionProvider, LocalSessionFactoryBean.setDataSource(javax.sql.DataSource), TransactionAwareDataSourceProxy, DataSourceUtils, JdbcTemplate

getDataSource

public DataSource getDataSource()

Return the JDBC DataSource that this instance manages transactions for.

setAutodetectDataSource

public void setAutodetectDataSource(boolean autodetectDataSource)

Set whether to autodetect a JDBC DataSource used by the Hibernate SessionFactory, if set via LocalSessionFactoryBean's setDataSource. Default is "true".

Can be turned off to deliberately ignore an available DataSource, in order to not expose Hibernate transactions as JDBC transactions for that DataSource.

See Also:

setDataSource(javax.sql.DataSource), LocalSessionFactoryBean.setDataSource(javax.sql.DataSource)

setPrepareConnection

public void setPrepareConnection(boolean prepareConnection)

Set whether to prepare the underlying JDBC Connection of a transactional Hibernate Session, that is, whether to apply a transaction-specific isolation level and/or the transaction's read-only flag to the underlying JDBC Connection.

Default is "true". If you turn this flag off, the transaction manager will not support per-transaction isolation levels anymore. It will not call Connection.setReadOnly(true) for read-only transactions anymore either. If this flag is turned off, no cleanup of a JDBC Connection is required after a transaction, since no Connection settings will get modified.

It is recommended to turn this flag off if running against Hibernate 3.1 and a connection pool that does not reset connection settings (for example, Jakarta Commons DBCP). To keep this flag turned on, you can set the "hibernate.connection.release_mode" property to "on_close" instead, or consider using a smarter connection pool (for example, C3P0).

See Also:

Connection.setTransactionIsolation(int), Connection.setReadOnly(boolean)

setEntityInterceptorBeanName

public void setEntityInterceptorBeanName(String entityInterceptorBeanName)

Set the bean name of a Hibernate entity interceptor that allows to inspect and change property values before writing to and reading from the database. Will get applied to any new Session created by this transaction manager.

Requires the bean factory to be known, to be able to resolve the bean name to an interceptor instance on session creation. Typically used for prototype interceptors, i.e. a new interceptor instance per session.

Can also be used for shared interceptor instances, but it is recommended to set the interceptor reference directly in such a scenario.

Parameters:

entityInterceptorBeanName - the name of the entity interceptor in the bean factory

See Also:

setBeanFactory(org.springframework.beans.factory.BeanFactory), setEntityInterceptor(org.hibernate.Interceptor)

setEntityInterceptor

public void setEntityInterceptor(Interceptor entityInterceptor)

Set a Hibernate entity interceptor that allows to inspect and change property values before writing to and reading from the database. Will get applied to any new Session created by this transaction manager.

Such an interceptor can either be set at the SessionFactory level, i.e. on LocalSessionFactoryBean, or at the Session level, i.e. on HibernateTemplate, HibernateInterceptor, and HibernateTransactionManager. It's preferable to set it on LocalSessionFactoryBean or HibernateTransactionManager to avoid repeated configuration and guarantee consistent behavior in transactions.

See Also:

LocalSessionFactoryBean.setEntityInterceptor(org.hibernate.Interceptor), HibernateAccessor.setEntityInterceptor(org.hibernate.Interceptor), HibernateAccessor.setEntityInterceptor(org.hibernate.Interceptor)

getEntityInterceptor

public Interceptor getEntityInterceptor()
                                 throws IllegalStateException,
                                        BeansException

Return the current Hibernate entity interceptor, or null if none. Resolves an entity interceptor bean name via the bean factory, if necessary.

Throws:

IllegalStateException - if bean name specified but no bean factory set

BeansException - if bean name resolution via the bean factory failed

See Also:

setEntityInterceptor(org.hibernate.Interceptor), setEntityInterceptorBeanName(java.lang.String), setBeanFactory(org.springframework.beans.factory.BeanFactory)

setJdbcExceptionTranslator

public void setJdbcExceptionTranslator(SQLExceptionTranslator jdbcExceptionTranslator)

Set the JDBC exception translator for this transaction manager.

Applied to any SQLException root cause of a Hibernate JDBCException that is thrown on flush, overriding Hibernate's default SQLException translation (which is based on Hibernate's Dialect for a specific target database).

Parameters:

jdbcExceptionTranslator - the exception translator

See Also:

SQLException, JDBCException, SQLErrorCodeSQLExceptionTranslator, SQLStateSQLExceptionTranslator

getJdbcExceptionTranslator

public SQLExceptionTranslator getJdbcExceptionTranslator()

Return the JDBC exception translator for this transaction manager, if any.

setBeanFactory

public void setBeanFactory(BeanFactory beanFactory)

The bean factory just needs to be known for resolving entity interceptor bean names. It does not need to be set for any other mode of operation.

Specified by:

setBeanFactory in interface BeanFactoryAware

Parameters:

beanFactory - owning BeanFactory (never null). The bean can immediately call methods on the factory.

See Also:

setEntityInterceptorBeanName(java.lang.String)

afterPropertiesSet

public void afterPropertiesSet()

Description copied from interface: InitializingBean

Invoked by a BeanFactory after it has set all bean properties supplied (and satisfied BeanFactoryAware and ApplicationContextAware).

This method allows the bean instance to perform initialization only possible when all bean properties have been set and to throw an exception in the event of misconfiguration.

Specified by:

afterPropertiesSet in interface InitializingBean

getResourceFactory

public Object getResourceFactory()

Description copied from interface: ResourceTransactionManager

Return the resource factory that this transaction manager operates on, e.g. a JDBC DataSource or a JMS ConnectionFactory.

This target resource factory is usually used as resource key for TransactionSynchronizationManager's resource bindings per thread.

Specified by:

getResourceFactory in interface ResourceTransactionManager

Returns:

the target resource factory (never null)

See Also:

TransactionSynchronizationManager.bindResource(java.lang.Object, java.lang.Object), TransactionSynchronizationManager.getResource(java.lang.Object)

doGetTransaction

protected Object doGetTransaction()

Description copied from class: AbstractPlatformTransactionManager

Return a transaction object for the current transaction state.

The returned object will usually be specific to the concrete transaction manager implementation, carrying corresponding transaction state in a modifiable fashion. This object will be passed into the other template methods (e.g. doBegin and doCommit), either directly or as part of a DefaultTransactionStatus instance.

The returned object should contain information about any existing transaction, that is, a transaction that has already started before the current getTransaction call on the transaction manager. Consequently, a doGetTransaction implementation will usually look for an existing transaction and store corresponding state in the returned transaction object.

Specified by:

doGetTransaction in class AbstractPlatformTransactionManager

Returns:

the current transaction object

See Also:

AbstractPlatformTransactionManager.doBegin(java.lang.Object, org.springframework.transaction.TransactionDefinition), AbstractPlatformTransactionManager.doCommit(org.springframework.transaction.support.DefaultTransactionStatus), AbstractPlatformTransactionManager.doRollback(org.springframework.transaction.support.DefaultTransactionStatus), DefaultTransactionStatus.getTransaction()

isExistingTransaction

protected boolean isExistingTransaction(Object transaction)

Description copied from class: AbstractPlatformTransactionManager

Check if the given transaction object indicates an existing transaction (that is, a transaction which has already started).

The result will be evaluated according to the specified propagation behavior for the new transaction. An existing transaction might get suspended (in case of PROPAGATION_REQUIRES_NEW), or the new transaction might participate in the existing one (in case of PROPAGATION_REQUIRED).

The default implementation returns false, assuming that participating in existing transactions is generally not supported. Subclasses are of course encouraged to provide such support.

Overrides:

isExistingTransaction in class AbstractPlatformTransactionManager

Parameters:

transaction - transaction object returned by doGetTransaction

Returns:

if there is an existing transaction

See Also:

AbstractPlatformTransactionManager.doGetTransaction()

doBegin

protected void doBegin(Object transaction,
                       TransactionDefinition definition)

Description copied from class: AbstractPlatformTransactionManager

Begin a new transaction with semantics according to the given transaction definition. Does not have to care about applying the propagation behavior, as this has already been handled by this abstract manager.

This method gets called when the transaction manager has decided to actually start a new transaction. Either there wasn't any transaction before, or the previous transaction has been suspended.

A special scenario is a nested transaction without savepoint: If useSavepointForNestedTransaction() returns "false", this method will be called to start a nested transaction when necessary. In such a context, there will be an active transaction: The implementation of this method has to detect this and start an appropriate nested transaction.

Specified by:

doBegin in class AbstractPlatformTransactionManager

Parameters:

transaction - transaction object returned by doGetTransaction

definition - TransactionDefinition instance, describing propagation behavior, isolation level, read-only flag, timeout, and transaction name

doSuspend

protected Object doSuspend(Object transaction)

Description copied from class: AbstractPlatformTransactionManager

Suspend the resources of the current transaction. Transaction synchronization will already have been suspended.

The default implementation throws a TransactionSuspensionNotSupportedException, assuming that transaction suspension is generally not supported.

Overrides:

doSuspend in class AbstractPlatformTransactionManager

Parameters:

transaction - transaction object returned by doGetTransaction

Returns:

an object that holds suspended resources (will be kept unexamined for passing it into doResume)

See Also:

AbstractPlatformTransactionManager.doResume(java.lang.Object, java.lang.Object)

doResume

protected void doResume(Object transaction,
                        Object suspendedResources)

Description copied from class: AbstractPlatformTransactionManager

Resume the resources of the current transaction. Transaction synchronization will be resumed afterwards.

The default implementation throws a TransactionSuspensionNotSupportedException, assuming that transaction suspension is generally not supported.

Overrides:

doResume in class AbstractPlatformTransactionManager

Parameters:

transaction - transaction object returned by doGetTransaction

suspendedResources - the object that holds suspended resources, as returned by doSuspend

See Also:

AbstractPlatformTransactionManager.doSuspend(java.lang.Object)

doCommit

protected void doCommit(DefaultTransactionStatus status)

Description copied from class: AbstractPlatformTransactionManager

Perform an actual commit of the given transaction.

An implementation does not need to check the "new transaction" flag or the rollback-only flag; this will already have been handled before. Usually, a straight commit will be performed on the transaction object contained in the passed-in status.

Specified by:

doCommit in class AbstractPlatformTransactionManager

Parameters:

status - the status representation of the transaction

See Also:

DefaultTransactionStatus.getTransaction()

doRollback

protected void doRollback(DefaultTransactionStatus status)

Description copied from class: AbstractPlatformTransactionManager

Perform an actual rollback of the given transaction.

An implementation does not need to check the "new transaction" flag; this will already have been handled before. Usually, a straight rollback will be performed on the transaction object contained in the passed-in status.

Specified by:

doRollback in class AbstractPlatformTransactionManager

Parameters:

status - the status representation of the transaction

See Also:

DefaultTransactionStatus.getTransaction()

doSetRollbackOnly

protected void doSetRollbackOnly(DefaultTransactionStatus status)

Description copied from class: AbstractPlatformTransactionManager

Set the given transaction rollback-only. Only called on rollback if the current transaction participates in an existing one.

The default implementation throws an IllegalTransactionStateException, assuming that participating in existing transactions is generally not supported. Subclasses are of course encouraged to provide such support.

Overrides:

doSetRollbackOnly in class AbstractPlatformTransactionManager

Parameters:

status - the status representation of the transaction

doCleanupAfterCompletion

protected void doCleanupAfterCompletion(Object transaction)

Description copied from class: AbstractPlatformTransactionManager

Cleanup resources after transaction completion.

Called after doCommit and doRollback execution, on any outcome. The default implementation does nothing.

Should not throw any exceptions but just issue warnings on errors.

Overrides:

doCleanupAfterCompletion in class AbstractPlatformTransactionManager

Parameters:

transaction - transaction object returned by doGetTransaction

isSameConnectionForEntireSession

protected boolean isSameConnectionForEntireSession(Session session)

Return whether the given Hibernate Session will always hold the same JDBC Connection. This is used to check whether the transaction manager can safely prepare and clean up the JDBC Connection used for a transaction.

Default implementation checks the Session's connection release mode to be "on_close". Unfortunately, this requires casting to SessionImpl, as of Hibernate 3.0/3.1. If that cast doesn't work, we'll simply assume we're safe and return true.

Parameters:

session - the Hibernate Session to check

See Also:

SessionImpl.getConnectionReleaseMode(), ConnectionReleaseMode.ON_CLOSE

convertHibernateAccessException

protected DataAccessException convertHibernateAccessException(HibernateException ex)

Convert the given HibernateException to an appropriate exception from the org.springframework.dao hierarchy.

Will automatically apply a specified SQLExceptionTranslator to a Hibernate JDBCException, else rely on Hibernate's default translation.

Parameters:

ex - HibernateException that occured

Returns:

a corresponding DataAccessException

See Also:

SessionFactoryUtils.convertHibernateAccessException(org.hibernate.HibernateException), setJdbcExceptionTranslator(org.springframework.jdbc.support.SQLExceptionTranslator)

convertJdbcAccessException

protected DataAccessException convertJdbcAccessException(JDBCException ex,
                                                         SQLExceptionTranslator translator)

Convert the given Hibernate JDBCException to an appropriate exception from the org.springframework.dao hierarchy, using the given SQLExceptionTranslator.

Parameters:

ex - Hibernate JDBCException that occured

translator - the SQLExceptionTranslator to use

Returns:

a corresponding DataAccessException

getDefaultJdbcExceptionTranslator

protected SQLExceptionTranslator getDefaultJdbcExceptionTranslator()

Obtain a default SQLExceptionTranslator, lazily creating it if necessary.

Creates a default SQLErrorCodeSQLExceptionTranslator for the SessionFactory's underlying DataSource.