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# Transactions

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TopLink provides the ability to write transactional code isolated from the underlying database and schema by using a unit of work.

The unit of work isolates changes in a transaction from other threads until it successfully commits the changes to the database. Unlike other transaction mechanisms, the unit of work automatically manages changes to the objects in the transaction, the order of the changes, and changes that might invalidate other TopLink caches. The unit of work manages these issues by calculating a minimal change set, ordering the database calls to comply with referential integrity rules and deadlock avoidance, and merging changed objects into the shared cache. In a clustered environment, the unit of work also synchronizes changes with the other servers in the coordinated cache.

If an application uses EJB entity beans, you do not access the unit of work API directly, but you still benefit from its features: the integration between the TopLink runtime and the J2EE container automatically uses the unit of work.

For more information, see "Understanding TopLink Transactions".