JBoss 4 is a J2EE 1.4 certified application server and thus supports client-controlled transaction, which is part of the J2EE specification. In other words, JBoss provides a Transaction Manager, there is no need for a separate transaction manager such as JOTM, Atomicos, etc.
JBoss Arjuna TS, JBoss 4.2 - .
. 4.2.3. UserTransaction Support .