Transactionsynchronizationregistry

Being in EJB and JPA world using CMT (Container Managed Transactions) is very comfortable. Just define few annotations to demarcate transaction boundary (or use the defaults) and that’s it – no fiddling with manual begin, commit or rollback operations. One way to rollback your transaction is to throw non-application exception (or application exception with rollback = true) from your EJB’s business method. It seems simple: if during some operation there is a possibility that an exception will be thrown and you don’t want to rollback your tx than you should just catch this exception and you’re fine. You can now retry the volatile operation once again within the same, still active transaction. ...

Few days ago I’ve created a simple interceptors spike-solution at Github. Its purpose was to show my colleagues that in the EJB’s interceptors you can implement a code that exists in the same transaction and the same security context as the called EJB business method. Moreover, you can benefit from all the dependency injection you need. This project uses the following resources injected by the Application Server: TransactionSynchronizationRegistry – used for getting current transaction key and checking if we’re in the same transaction (I’ve written about it e.g. here), SessionContext – for reading user’s principal – user’s security context is also available in the interceptor, EntityManager – to persist some data before invoking the business method; it exists in the same transaction as the called method, so either both: the interceptor persistence and business method ends with success or both of them will be rolled-back. This example also shows how easily you can add RESTful Web Service to your application (take a look at com.piotrnowicki.interceptors.web package). ...