How Transaction Rollback within multiple EJB

Question

Hello,
I am new to EJB, i would like to know how does the transaction could be rollback..? For instances in our project, the session
bean act as the manager for control the transaction in action class..
For Example;
Table A, Table B, Table C, Table D
In this case, each table are acts as one EJB, and for sure there was 4 session bean, session bean A(AManager), session bean B(BManager), session bean C(CManager), session bean D(DManager)... and EJB A, EJB B, EJB C, EJB D....
In the action class
There was one transaction involve 4 table, for example;
AManager manager = (AManager) EJBService.getFactory().lookUpManager("AManager",AManagerHome.class);
follow in.. B,C and D also same calling the Manager(session bean ) class...
try
{AManager.add("something);}
Catch(Exception e){}
try
{BManager.add("something);}
Catch(Exception e){}
try
{CManager.add("something);}
Catch(Exception e){}
try
{DManager.add("something);}
Catch(Exception e){}
If there was error in transaction CManager, how does all the transaction (AManager,BManager)could be rollback?
Any suggession? any good website? Thanks for all your help guideness...
Feel very appreciate for any help...

Answer 1

Hi,
From your description I can model your problem like this:
You have one method executing one particular task involving four session EJBs like this:
public void performTask(){
try{
AManager.add("something);
}catch(Exception e){}
try{
BManager.add("something);
Catch(Exception e){}
try{
CManager.add("something);
Catch(Exception e){}
try{
DManager.add("something);
Catch(Exception e){}
Now I will introduce another concept: Session Facade. And our performTask() method belongs to Session Facade. Session Facade is nothing but another session bean which the client talk to.
Now your problem is:
"CManager.add() creates some problems, then want to rollback the whole transaction-- specifically you want to rollback whatever done through AManager.add() and BManager.add() methods."
Solution Steps:
============
1. Set the transaction-attribute of performTask() method to
RequiresNew. It means whenever client(any java application or
other EJB) invokes the performTask() method, this method starts
execution in a new transaction context.
2. Now set the transaction attribute of Session A, Session B, Session
C, Session D, EJB A, EJB B, EJB C, and EJB D in such a way that
transaction context of performTask() method should be propagated
to these Enterprise beans. It means when you are calling
AManager.add() method from performTask() method, the
AManager.add() method should be executed under the same
transaction context as of parformTask(). Also true for other manager.
3. Throw System Exception when you will get some error inside
CManager.add() method. This will automatically rollback the
transaction. You don't need to worry.
Does it solve your problem? For further information you should go through the following book:
Enterprise Java Beans, Orielly Publication