T R A N S A C T I O N S  

Transactions can become trickier when you need to use third party applications if internal or 

external. Now a transaction must include this third party application by handing over the 

transactions to the other party meaning we need a distributed transaction. This sounds not 

much more complicated but considering the fact that the connection to the third party 

application is lost or it does not respond in time we maybe have to determine the outcome 

heuristic to go on with our application. Heuristic because the application does not know 

where the failure was, the client could not have received the request, the request could have 

been processed successful or could have failed or when the third party application responded 

but the connection dropped beforehand. 

Transactions are associated with threads. When a thread calls a component, the transaction 

is automatically propagated with the thread of execution. This happens for local as well as 

remote calls. 

In J2EE nested transactions are not allowed. Therefore we cannot have a transaction inside 

another transaction. But using the javax.transaction.TransactionManager interface it is 

possible to suspend a transaction and then use no transaction or another transaction. This 

allows the application server to perform actions outside the given transaction in its own 

transaction or completely without one. After these steps are done the transaction is 

reactivated and the next steps can be performed. Please note that the TransactionManager 

interface is not meant to be used by components hosted by the J2EE server. Components 

should always use the javax.transaction.UserTransaction interface instead. 

In J2EE the bean developer has two choices how to use transactions. Either he can let the 

container managed the transactions or he can managed transactions in the bean. 

Container Managed Transaction (CMT) 

In a CMT bean the container manage the transactions. How to do so is specified by the 

transaction attributes in the bean deployment descriptor ( trans attribute ). The following 

graphics uses a black arrow for a call without a transaction, a blue arrow for a transaction 

coming from the caller, a red arrow for a new transaction created in the transaction 

interceptor that is indicated by the dark gray box. There are six different transaction 

attributes: 

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