Transactions

[chatbuilder]

Hi,

I have difficulties to understand how to set up transactions.

I'm using servlets and CMP entitity beans.

On my servlet I want to do the following.

//Start transaction
client.pay(500);
book.soldAmount(10);
//commit transaction

I'm using entity beans, so I'm not sure if I can use javax.transaction.UserTransaction.

Thx in advance,
Pieter

[chatbuilder]

It seems to work like this:

InitialenRemote initiaal = null;
Context context = new InitialContext();
UserTransaction userTran = (UserTransaction)context.lookup("UserTransaction");
try{
 userTran.begin();

 String strInitiaal = initialenForm.getInitiaal();
 Object einRef = context.lookup("Initiaal");
 InitialenHomeRemote home = (InitialenHomeRemote)PortableRemoteObject.narrow(einRef, InitialenHomeRemote.class);
 initiaal = home.create(strInitiaal);

 userTran.commit();
}catch(Exception e){
 userTran.rollback();
 e.printStackTrace();
}

But I'm not sure if this is the right way...

[hariv]

You cannot use UserTransaction in entity Bean. Entity Beans can have only CMT(Container Managed Transaction). If you set the the transaction isolation level as required in your entity bean methods. The method will join the already created transaction from the caller of the method. In the servelet you can user UserTransaction and set the methods in entity bean with Transaction Required isolation level

[chatbuilder]

Hi hariv,

Can you give a bit more details how to implement this?

Some code would be nice.

Thx,
Pieter

[kero]

You need to add these in your ejb-jar
---------------------------------------------

<container-transaction>

<ejb-name>YourEJBname</ejb-name>
<method-intf>Remote</method-intf>
<method-name>YourMethodName</method-name>

<trans-attribute>RequiresNew</trans-attribute>
</container-transaction>

-----------------------------------------------
for the trans-attribute tag, there are a few option and you can read from sun.

in >YourMethodName, you may set up a condition and do the rollback as :
-----------------------------------------------

context.setRollbackOnly();
} catch (Exception ee) {
ee.printStackTrace();
}
-----------------------------------------------

[chatbuilder]

I use the usertransaction for CMP entity beans, and I must say it really works... I have also readed on the internet that userTransactions are only for session beans. So I don't have a clue why it works with me.

below the code of my action, of my struts application

public ActionForward update(ActionMapping mapping,
 ActionForm form,
 HttpServletRequest request,
 HttpServletResponse response)
throws Exception{

 Context context = new InitialContext();
 UserTransaction userTran = (UserTransaction)context.lookup("UserTransaction");
 try{

 InitialenForm initialenForm = (InitialenForm)form;
 userTran.begin();

 Object ref = context.lookup("Initiaal");
 InitialenHomeRemote home = (InitialenHomeRemote)PortableRemoteObject.narrow(ref, InitialenHomeRemote.class);

 home.create("NOT","NOT","NOT","NOT","NOT");

 InitialenRemote initiaal = home.findByPrimaryKey(initialenForm.getId());
 initiaal.update(initialenForm.getInitiaal(),
 initialenForm.getNaam(),
 initialenForm.getDienst(),
 initialenForm.getInterneEmail(),
 initialenForm.getTelefoon(),
 initialenForm.getLockIndicator());
 initialenForm.setLockIndicator(initiaal.getLockindicator());


 userTran.commit();

 ActionMessages messages = new ActionMessages();
 messages.add("initiaal",new ActionMessage("initiaal.successvol.opgeslaan", initialenForm.getInitiaal()));
 saveMessages(request,messages);
 }catch(ActionException e){
 userTran.rollback();
 saveExceptions(request,e);
 }catch(Exception ex){
 userTran.rollback();
 throw ex;
 }
 return mapping.findForward(IConstants.INPUT_KEY);
}

My update method of my bean throws an ActionException (selfmade -exception) when the name is empty.

So when initialenForm.getNaam() is empty, I get a ROLLBACK. And when I check my MySQL database, I see that the home.create("NOT","NOT","NOT","NOT","NOT"); is also rollback.

Strange!!!