Head First EJB

The UserTransaction interface

(javax.transaction.UserTransaction)

Sharpen your pencil

The UserTransaction interface has six methods for the things a BMT bean might want to do. Try to figure out the method names, based on the description of what you want to do. (The answers are at the bottom, upside down, so don’t look down there.)

1. Begin a transaction

   ut.______________________

2. End a transaction

   ut.______________________
   // or
   ut.______________________

   Note

   UserTransaction is for BMT beans only! A CMT bean is never supposed to get (or try to use) a reference to a UserTransaction.

3. Mark a transaction for rollback

   ut.______________________

   Note

   UserTransaction is NOT for entity beans. Since entity beans MUST be CMT, if you see UserTransaction code in an entity bean, you know the code’s not legal.

4. Find out the status of the transaction

   ut.______________________

5. Set the transaction timeout

   ut.______________________

Relax

There’s nothing about transaction timeout on the exam.

All transactions have some default timeout value, but you can change that with:

setTransactionTimeout(anIntValue). As a bean developer, you’ll probably never use anything but the default timeout value, so we don’t test for it on the exam.

1. begin(), 2. commit() or rollback(), 3. setRollbackOnly(), 4. getStatus(), 5. setTransactionTimeout()