Nested Transactions are not supported by J2EE.

Question

I am a relative newbie to J2EE and am trying to get my head around transactions. I will use the following components to illustrate my questions.
I have two container managed enterprise beans, Bean-1 and Bean-2. Bean-1 has a single method method-A. Bean-2 also has a single method method-B. The code in method-A calls method-B.
We have the following scenarios:
1. A servelet calls method-A, starting a new transaction. Method-A calls method-B.
2. Another servlet calls method-B starting a new transaction.
And now for my first questions ......
Am I right in saying that, as the beans are container managed, scenario 1 does not create a nested transaction as the begin and commit are controlled by the container and only issued at the beginning / end of the overall transaction as appropriate.
Now lets change the set-up slightly. Lets assume that both beans have bean managed transactions using JTA. At the beginning and end of both method calls appropriate begin / commit / abort code is inserted.
And now the second question ......
A call to method-B starting a new transaction (scenario 2) works fine. Am I right in saying that a call to method-A under scenario 1 would not be allowed as when method-A calls method-B a nested transaction would occur as both methods have begin / commit code.
Thanks any help with this query.
Paul

Answer 1

hello
We have a very strange problem in our application.
I have the following code in an MDB onMessage() metod
// inserts 100 rows into table1
//in the dploymentdescriptor method is marked with requiednew
statelessSessionBean1.generaterowsWithNewTransaction();
//updates a row in table2
//in the dploymentdescriptor method is marked with requiednew
statelessSessionBean2.updaterow1WithNewTransaction();
//updates a row in table3
//in the dploymentdescriptor method is marked with requiednew
statelessSessionBean3.updaterow2WithNewTransaction();
when the above code is successfully executed and transactions are
committed succussfully, we have at times the situation like the first
100 lines inserted into DB are not available but the other two table
rows are updated. After a while if we see again in DB we are finding
the 100 rows as well. Again this situation happens very sporadically.
Any help would be appreciated. Thanks in advance.
Venkat