Transaction (internal-api module for cmp 4.0 API)

```
public interface Transaction
```
The JDO Transaction interface is a sub-interface of the PersistenceManager that deals with options and completion of transactions under user control.
Transaction options include whether optimistic concurrency control should be used for the current transaction, and whether values should be retained in JDO instances after transaction completion.
Transaction completion methods have the same semantics as javax.transaction UserTransaction, and are valid only in the non-managed, non-distributed transaction environment.

Version:

0.1

Author:

Craig Russell

Method Summary

Methods
Modifier and Type	Method and Description
`void`	`begin()` Begin a transaction.
`void`	`commit()` Commit the current transaction.
`boolean`	`getNontransactionalRead()` If this flag is set to true, then queries and navigation are allowed without an active transaction
`boolean`	`getOptimistic()` Optimistic transactions do not hold data store locks until commit time.
`PersistenceManager`	`getPersistenceManager()` The Tranansaction instance is always associated with exactly one PersistenceManager.
`int`	`getQueryTimeout()` Gets the number of seconds to wait for a query statement to execute in the datastore associated with this Transaction instance
`boolean`	`getRestoreValues()` If true, at rollback time instances restore their field values.
`boolean`	`getRetainValues()` If true, at commit time instances retain their field values.
`Synchronization`	`getSynchronization()` The user-specified Synchronization instance for this Transaction instance.
`int`	`getUpdateTimeout()` Gets the number of seconds to wait for an update statement to execute in the datastore associated with this Transaction instance
`boolean`	`isActive()` Returns whether there is a transaction currently active.
`void`	`rollback()` Roll back the current transaction.
`void`	`setNontransactionalRead(boolean flag)` If this flag is set to true, then queries and navigation are allowed without an active transaction
`void`	`setOptimistic(boolean optimistic)` Optimistic transactions do not hold data store locks until commit time.
`void`	`setQueryTimeout(int timeout)` Sets the number of seconds to wait for a query statement to execute in the datastore associated with this Transaction instance
`void`	`setRestoreValues(boolean restoreValues)` If true, at rollback instances restore their values and the instances transition to persistent-nontransactional.
`void`	`setRetainValues(boolean retainValues)` If true, at commit instances retain their values and the instances transition to persistent-nontransactional.
`void`	`setSynchronization(Synchronization sync)` The user can specify a Synchronization instance to be notified on transaction completions.
`void`	`setUpdateTimeout(int timeout)` Sets the number of seconds to wait for an update statement to execute in the datastore associated with this Transaction instance

- Method Detail
  - begin
```
void begin()
```
    Begin a transaction. The type of transaction is determined by the setting of the Optimistic flag.
    
    Throws:
    
    JDOUserException - if a distributed transaction XAResource is assigned to this Transaction
    See Also:
    setOptimistic(boolean), getOptimistic()
  - commit
```
void commit()
```
    Commit the current transaction.
  - rollback
```
void rollback()
```
    Roll back the current transaction.
  - isActive
```
boolean isActive()
```
    Returns whether there is a transaction currently active.
    
    Returns:
    boolean
  - setRetainValues
```
void setRetainValues(boolean retainValues)
```
    If true, at commit instances retain their values and the instances transition to persistent-nontransactional.
    Setting this flag also sets the NontransactionalRead flag.
    
    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 instances restore their values and the instances transition to persistent-nontransactional.
    
    Parameters:
    restoreValues - the value of the restoreValues property
  - getRestoreValues
```
boolean getRestoreValues()
```
    If true, at rollback time instances restore their field values.
    
    Returns:
    the value of the restoreValues property
  - setOptimistic
```
void setOptimistic(boolean optimistic)
```
    Optimistic transactions do not hold data store locks until commit time.
    
    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.
  - setNontransactionalRead
```
void setNontransactionalRead(boolean flag)
```
    If this flag is set to true, then queries and navigation are allowed without an active transaction
    
    Parameters:
    flag - the value of the nontransactionalRead property.
  - getNontransactionalRead
```
boolean getNontransactionalRead()
```
    If this flag is set to true, then queries and navigation are allowed without an active transaction
    
    Returns:
    the value of the nontransactionalRead property.
  - setSynchronization
```
void setSynchronization(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 the data store commit operation.
    
    Parameters:
    sync - the Synchronization instance to be notified; null for none
  - getSynchronization
```
Synchronization getSynchronization()
```
    The user-specified Synchronization instance for this Transaction instance.
    
    Returns:
    the user-specified Synchronization instance.
  - setQueryTimeout
```
void setQueryTimeout(int timeout)
```
    Sets the number of seconds to wait for a query statement to execute in the datastore associated with this Transaction instance
    
    Parameters:
    timeout - new timout value in seconds; zero means unlimited
  - getQueryTimeout
```
int getQueryTimeout()
```
    Gets the number of seconds to wait for a query statement to execute in the datastore associated with this Transaction instance
    
    Returns:
    timout value in seconds; zero means unlimited
  - setUpdateTimeout
```
void setUpdateTimeout(int timeout)
```
    Sets the number of seconds to wait for an update statement to execute in the datastore associated with this Transaction instance
    
    Parameters:
    timeout - new timout value in seconds; zero means unlimited
  - getUpdateTimeout
```
int getUpdateTimeout()
```
    Gets the number of seconds to wait for an update statement to execute in the datastore associated with this Transaction instance
    
    Returns:
    timout value in seconds; zero means unlimited
  - getPersistenceManager
```
PersistenceManager getPersistenceManager()
```
    The Tranansaction instance is always associated with exactly one PersistenceManager.
    
    Returns:
    the PersistenceManager for this Transaction instance

Interface Transaction

Method Summary

Method Detail

begin

commit

rollback

isActive

setRetainValues

getRetainValues

setRestoreValues

getRestoreValues

setOptimistic

getOptimistic

setNontransactionalRead

getNontransactionalRead

setSynchronization

getSynchronization

setQueryTimeout

getQueryTimeout

setUpdateTimeout

getUpdateTimeout

getPersistenceManager