Core Java™ Data Objects

3.5. Creating an Object

After a PersistenceManager has been retrieved, it is possible to actually begin a transaction and do something interesting with the datastore. To begin a transaction, get the current Transaction instance from the PersistenceManager:

public Transaction currentTransaction()

And call the begin() method on Transaction to start a datastore transaction:

public void begin()

Typically, any interaction with a datastore is done within the context of a transaction. A transaction simply marks the beginning and end of a unit of work, whereby all changes made either happen or do not happen.

A transaction is also the mechanism that a datastore uses to enforce concurrency control between multiple applications accessing the datastore ...