EJB with transactional state

Problem: EJBean, like any POJO, can have fields. We want the changes made to the fields to be rolled back if a transaction is rolled back.

Let us consider the following scenario:

  1. Client starts transaction
  2. Client invokes EJB and propagates transaction
  3. Assume that EJBean have field int number initially equals 0, method invoked by client sets the field number to 1
  4. Client rollbacks transaction
  5. It turns out that value of field number is not rolled back, the value remains 1

EJB supports global transactions but they are not transactional. I.e. they can propagate transaction to Managed Resources, for instance a database connection, but the state of EJBean does not participate in a transaction, like in the above scenario.

To make a state of EJB transactional, we must do it manually, i.e. we must provide a mechanism that restores state in a case of rollback. This can be achieved by transaction listeners. But only possible type of EJB that support such listeners is Stateful Session Bean.

public class TUBean {
   private TUState state;
   private TUState rollbackState;

   private void init(){
      state = new TUState();

   //business methods

   private void afterBegin(){
      rollbackState = state.clone();

   private void afterCompletion(boolean committed){
      if ( ! committed )
         state = rollbackState;
      rollbackState = null;

The class TUState encapsulates whole transactional state. The state is rather simple, like POJO, without database connections. For convenience we assume that the method clone is well implemented.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: