Implementing transaction in EJB with javax.transaction.UserTransaction - jboss

Question

I am implementing an EJB application. At this point I need a transaction. I need to execute 3 methods in row and if one fails, everything should be rolled back.
Here: http://www.conceptgo.com/gsejb/eb04.html, I have found a tutorial.
My code:
try {
javax.transaction.UserTransaction ut = (UserTransaction) ctx.lookup("java:comp/UserTransaction");
ut.begin();
Feeds feed = loadFeed(url);
try{
em.persist(feed);
uf.setFeedId(feed.getFeedId());
uf.setUserId(user_id);
em.persist(uf);
}catch (EntityExistsException e){
ut.rollback();
return false;
}catch (IllegalArgumentException ea){
ut.rollback();
return false;
}
if (feed.getFeedId()!= null && feed!=null) {
ut.commit();
}else{
ut.rollback();
return false;
}
When I run my app I get next error message:
Caused by: java.lang.IllegalStateException: BaseTransaction.checkTransactionState
- ARJUNA016051: thread is already associated with a transaction
Anyone knows what's the cause and how to solve it?

Answer 1

The error means that you already have a transaction in progress, more than likely a container managed transaction.
What does your bean/method look like? The default transaction behavior for a stateless session bean in JBoss7 is that it executes with Container managed transaction and with 'Required' transaction attribute.
So assuming that container managed transactions work for you, you don't need the UserTransaction. So you can remove the lookup and the begin/commit/rollback since that will be managed for you.
If you do want to manage transactions yourself, then mark the bean as using Bean managed transactions and then you can begin/commit/rollback the UserTransaction. To mark a bean as using bean managed transactions, you will apply the annotation #TransactionManagement(TransactionManagementType.BEAN) to the class or method.

Answer 2

As error shows you are try to interrupt container managed transaction in JBoss. If you want to deal with transaction with own way then change your class/method bean managed like.
#TransactionManagement(TransactionManagementType.BEAN)
public void getTransaction(){
//....
}
Now you are safe from JBoss end but ensure you have to define each step of transaction in Bean managed Transaction.

Answer 3

It is not advisable to use few steps for CMT and few steps for BMT because in case CMT container will responsible for handling transaction and associated thread. So ejb container will acquire lock on objects participated in transaction and will not be released until transaction completed these objects may cause of problem if you need it in BMT. So you have to either use CMT or BMT .