Java Data Objects

Transient-Transactional Instances

You can cause transient instances to observe transaction boundaries, such that their state is preserved at commit and restored on rollback. A transient instance that observes transaction boundaries is called a transient-transactional instance . Support for transient-transactional instances is optional; their use requires support of the optional TransientTransactional feature. If your implementation does not support TransientTransactional, it will not include the functionality that causes the state transitions associated with transient-transactional instances.

You can use the following PersistenceManager methods to make transient instances transactional:

void makeTransactional(Object obj);
void makeTransactionalAll(Object[] objs);
void makeTransactionalAll(Collection objs);

After these methods complete, the instances observe transaction boundaries. If the transaction commits, the transient-transactional instances retain their values. The makeTransactional( ) method throws a JDOUnsupportedOptionException if you pass a transient instance as a parameter and the implementation does not support the optional TransientTransactional feature.

If the call to makeTransactional( ) is made within the current transaction and the transaction is rolled back, the fields of the transient-transactional instances are restored to the values they had when makeTransactional( ) was called, using their captured before image (discussed in Chapter 14). If the call to makeTransactional( ...