They recommend using JTA transaction support in Java EE environment.
But how to configure JTA in Tomcat6 so that Hibernate Session could use it ?
Starting with version 3.0.1, Hibernate added the
SessionFactory.getCurrentSession()
method. Initially, this assumed usage of JTA transactions, where the JTA transaction defined both the scope and context of a current session. Given the maturity of the numerous stand-alone JTA TransactionManager implementations, most, if not all, applications should be using JTA transaction management, whether or not they are deployed into a J2EE container. Based on that, the JTA-based contextual sessions are all you need to use.
(Hibernate Reference Documentation | Architecture. Contextual Sessions)
If you want JTA support in Tomcat you'll need to use a standalone transaction manager like Atomikos, JOTM, Bitronix, SimpleJTA, JBossTS or GeronimoTM/Jencks. But honestly, if you're not going to handle transactions across multiple resources, then you can live without JTA (and if you really need JTA, use a full blown application server).