javax.jdo
Interface Transaction


public interface Transaction

The JDO Transaction interface provides for initiation and completion of transactions under user control. It is a sub-interface of the PersistenceManager that deals with options and transaction demarcation.

Transaction options include whether optimistic concurrency control should be used for the current transaction, whether instances may hold values in the cache outside transactions, and whether values should be retained in the cache after transaction completion. These options are valid for both managed and non-managed transactions.

Transaction initiation and completion methods have similar semantics to javax.transaction.UserTransaction when used outside a managed environment. When used in a managed environment, transaction initiation and completion methods may only be used with bean-managed transaction semantics.

Version:
2.3

Method Summary
 void begin()
          Begin a transaction.
 void commit()
          Commit the current transaction.
 java.lang.String getIsolationLevel()
          Get the value for transaction isolation level for this transaction.
 boolean getNontransactionalRead()
          If true, allows persistent instances to be read without a transaction active.
 boolean getNontransactionalWrite()
          If true, allows persistent instances to be written without a transaction active.
 boolean getOptimistic()
          Optimistic transactions do not hold data store locks until commit time.
 PersistenceManager getPersistenceManager()
          The Transaction instance is always associated with exactly one PersistenceManager.
 boolean getRestoreValues()
          Return the current value of the restoreValues property.
 boolean getRetainValues()
          If true, at commit time instances retain their field values.
 boolean getRollbackOnly()
          Returns the rollback-only status of the transaction.
 java.lang.Boolean getSerializeRead()
          Return the current value of the serializeRead property.
 javax.transaction.Synchronization getSynchronization()
          The user-specified Synchronization instance for this Transaction instance.
 boolean isActive()
          Returns whether there is a transaction currently active.
 void rollback()
          Roll back the current transaction.
 void setIsolationLevel(java.lang.String level)
          Set the value for transaction isolation level for this transaction.
 void setNontransactionalRead(boolean nontransactionalRead)
          If true, allow persistent instances to be read without a transaction active.
 void setNontransactionalWrite(boolean nontransactionalWrite)
          If true, allow persistent instances to be written without a transaction active.
 void setOptimistic(boolean optimistic)
          Optimistic transactions do not hold data store locks until commit time.
 void setRestoreValues(boolean restoreValues)
          If true, at rollback, fields of newly persistent instances are restored to their values as of the beginning of the transaction, and the instances revert to transient.
 void setRetainValues(boolean retainValues)
          If true, at commit instances retain their values and the instances transition to persistent-nontransactional.
 void setRollbackOnly()
          Sets the rollback-only status of the transaction to true.
 void setSerializeRead(java.lang.Boolean serialize)
          If true, a lock will be applied to all objects read in this transaction.
 void setSynchronization(javax.transaction.Synchronization sync)
          The user can specify a Synchronization instance to be notified on transaction completions.
 

Method Detail

begin

void begin()
Begin a transaction. The type of transaction is determined by the setting of the Optimistic flag.

Throws:
JDOUserException - if transactions are managed by a container in the managed environment, or if the transaction is already active.
See Also:
setOptimistic(boolean), getOptimistic()

commit

void commit()
Commit the current transaction.

Throws:
JDOUserException - if transactions are managed by a container in the managed environment, or if the transaction is not active.

rollback

void rollback()
Roll back the current transaction.

Throws:
JDOUserException - if transactions are managed by a container in the managed environment, or if the transaction is not active.

isActive

boolean isActive()
Returns whether there is a transaction currently active.

Returns:
true if the transaction is active.

getRollbackOnly

boolean getRollbackOnly()
Returns the rollback-only status of the transaction. When begun, the rollback-only status is false. Either the application or the JDO implementation may set this flag using setRollbackOnly.

Returns:
true if the transaction has been marked for rollback.
Since:
2.0

setRollbackOnly

void setRollbackOnly()
Sets the rollback-only status of the transaction to true. After this flag is set to true, the transaction can no longer be committed, and any attempt to commit the transaction will throw JDOFatalDataStoreException.

Since:
2.0

setNontransactionalRead

void setNontransactionalRead(boolean nontransactionalRead)
If true, allow persistent instances to be read without a transaction active. If an implementation does not support this option, a JDOUnsupportedOptionException is thrown.

Parameters:
nontransactionalRead - the value of the nontransactionalRead property

getNontransactionalRead

boolean getNontransactionalRead()
If true, allows persistent instances to be read without a transaction active.

Returns:
the value of the nontransactionalRead property

setNontransactionalWrite

void setNontransactionalWrite(boolean nontransactionalWrite)
If true, allow persistent instances to be written without a transaction active. If an implementation does not support this option, a JDOUnsupportedOptionException is thrown.

Parameters:
nontransactionalWrite - the value of the nontransactionalRead property

getNontransactionalWrite

boolean getNontransactionalWrite()
If true, allows persistent instances to be written without a transaction active.

Returns:
the value of the nontransactionalWrite property

setRetainValues

void setRetainValues(boolean retainValues)
If true, at commit instances retain their values and the instances transition to persistent-nontransactional. If an implementation does not support this option, a JDOUnsupportedOptionException is thrown.

Parameters:
retainValues - the value of the retainValues property

getRetainValues

boolean getRetainValues()
If true, at commit time instances retain their field values.

Returns:
the value of the retainValues property

setRestoreValues

void setRestoreValues(boolean restoreValues)
If true, at rollback, fields of newly persistent instances are restored to their values as of the beginning of the transaction, and the instances revert to transient. Additionally, fields of modified instances of primitive types and immutable reference types are restored to their values as of the beginning of the transaction.

If false, at rollback, the values of fields of newly persistent instances are unchanged and the instances revert to transient. Additionally, dirty instances transition to hollow. If an implementation does not support this option, a JDOUnsupportedOptionException is thrown.

Parameters:
restoreValues - the value of the restoreValues property

getRestoreValues

boolean getRestoreValues()
Return the current value of the restoreValues property.

Returns:
the value of the restoreValues property

setOptimistic

void setOptimistic(boolean optimistic)
Optimistic transactions do not hold data store locks until commit time. If an implementation does not support this option, a JDOUnsupportedOptionException is thrown.

Parameters:
optimistic - the value of the Optimistic flag.

getOptimistic

boolean getOptimistic()
Optimistic transactions do not hold data store locks until commit time.

Returns:
the value of the Optimistic property.

getIsolationLevel

java.lang.String getIsolationLevel()
Get the value for transaction isolation level for this transaction.

Returns:
the transaction isolation level
Since:
2.2
See Also:
setIsolationLevel(String)

setIsolationLevel

void setIsolationLevel(java.lang.String level)
Set the value for transaction isolation level for this transaction. Transaction isolation levels are defined in javax.jdo.Constants. If the requested level is not available, but a higher level is available, the higher level is silently used. If the requested level is not available, and no higher level is available, then JDOUnsupportedOptionException is thrown. Five standard isolation levels are defined. Other isolation levels might be supported by an implementation but are not standard.

Standard values in order of low to high are:

  • read-uncommitted
  • read-committed
  • repeatable-read
  • snapshot
  • serializable

Parameters:
level - the transaction isolation level
Since:
2.2
See Also:
getIsolationLevel(), Constants.TX_READ_UNCOMMITTED, Constants.TX_READ_COMMITTED, Constants.TX_REPEATABLE_READ, Constants.TX_SNAPSHOT, Constants.TX_SERIALIZABLE

setSynchronization

void setSynchronization(javax.transaction.Synchronization sync)
The user can specify a Synchronization instance to be notified on transaction completions. The beforeCompletion method is called prior to flushing instances to the data store.

The afterCompletion method is called after performing state transitions of persistent and transactional instances, following the data store commit or rollback operation.

Only one Synchronization instance can be registered with the Transaction. If the application requires more than one instance to receive synchronization callbacks, then the single application instance is responsible for managing them, and forwarding callbacks to them.

Parameters:
sync - the Synchronization instance to be notified; null for none

getSynchronization

javax.transaction.Synchronization getSynchronization()
The user-specified Synchronization instance for this Transaction instance.

Returns:
the user-specified Synchronization instance.

getPersistenceManager

PersistenceManager getPersistenceManager()
The Transaction instance is always associated with exactly one PersistenceManager.

Returns:
the PersistenceManager for this Transaction instance

setSerializeRead

void setSerializeRead(java.lang.Boolean serialize)
If true, a lock will be applied to all objects read in this transaction.

If false then retrieved objects will not be locked. If null will fallback to the value for metadata for the class in question.

Parameters:
serialize - the value of the serializeRead property
Since:
2.3

getSerializeRead

java.lang.Boolean getSerializeRead()
Return the current value of the serializeRead property.

Returns:
the value of the serializeRead property
Since:
2.3


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