UserTransaction - Scope using JNDI lookup from jspInit() method

Question

Howdy,
I'm using JSP's with JavaBeans accessing a DataSource and some other enviroment variables using JNDI lookups. I've read that JNDI lookups can take a fair amount of time and should be limited whenever possible. My previous configuration had the JNDI lookups inside the constructors of the JavaBeans but I've recently decided to move them to the jspInit() method of the calling JSP. This way the lookup only needs to be performed once and then I pass the values to the JavaBean in a method called setContextVariables. Two of the references to objects that i'm sending are the UserTransaction and DataSource objects. Within the Javabeans I have userTran.begin() and commit() statements. So far it's running great but i'm starting to wonder about the thread safety of this method. My question lies in the actual delagation of the UserTransaction object to the calling client method. It seems that i'm passing the same transaction to every Javabean (or am I?) Is the transaction actually issued when the begin() method is called, or at the time of the JNDI lookup? To test everything out, I opened two sessions and put a breakpoint inside one of the transactions. When I stopped at the breakpoint I ran another thread (also using a transaction retrieved from the same JSP). Then I went back and resumed the first thread and everything seemed to work ok. So... this seems completely fantabulastic so far (definitely noticable response time increases) but I'm still a little skeptical. If anyone is using a process similar to this I would appreciate some feedback. Thanks.

Answer 1

Hi,
The EJB bean will use the client transaction when the following attributes are specified in descriptor.
1) Required
2) Mandatory
3) Supports
In Required case, if the client is associated with Transaction, then the EJB bean will use the same transaction. This is achieved by Transaction context. The EJB bean will use the same transaction context set by client. if the client doesn't have any transaction, then the container will create new transaction context for EJB bean and completes the transaction.
In Mandatory case, the client must be associated with Transaction so that EJB bean will use the same transaction. If the client doesn't associate with transaction, then container will throw TransactionRequiredException for EJB bean.
In Supports case, it works similar to Required case except that if the client doesn't associate with transaction, then there won't be any transaction in EJB bean.
hope this helps.