I did not refer to HF or the ejb spec. I have just started preparing for the SCBCD but have gone thru Mastering EJB by Ed Roman both 2 & 3 Editions at my work.
I was refering to pg 241 & 242 of Mastering EJB Edition 3.
The following is the text:
MDBs do not run in the same tx as the producer who sends the messages, because there are typically 2 tx associated with every durable JMS message (one tx for producers to put the message on the q, and another tx for the JMS mdb to get the message off the queue). It is theoretically impoissible for the JMS mdb to participate in the same Tx as the producer, because until the producer commits the tx, the message would'nt even appear on the q.