How do I make my MDB transactional?

I found from the application trace  that my MDB was doing MQGET, MQCMIT in the listener, and MQOPEN, MQPUT, MQCLOSE and no MQCMIT in my application.    Digging into this I found that the MQPUT was NO_SYNCPOINT, which was a surprise to me!

My application had session = connection.createSession(true, 1); // true = transactional. So I expected it to work.

The ejb-jar.xml had

enterprise-beans
  message-driven
    transaction-type Container
...
assembly-descriptor
  container-transaction
    trans-attribute NotSupported

I changed NotSupported to Required and it worked.

The application trace for the Listener part of the MDB gave me

Operation      CompCode MQRC HObj (ObjName) 
MQXF_XASTART            0000 -
MQXF_GET       MQCC_OK  0000    2 (JMSQ2 )
MQXF_XAEND              0000 -
MQXF_XAPREPARE          0000 -
MQXF_XACOMMIT           0000 -

The trace for the application part of the MDB gave me

Operation                    CompCode MQRC HObj (ObjName)
MQXF_XASTART                             0000         –
MQXF_OPEN             MQCC_OK   0000         2 (CP0000 )
MQXF_PUT                MQCC_OK   0000          2 (CP0000 )
MQXF_CLOSE           MQCC_OK   0000          2 (CP0000 )
MQXF_XAEND                                0000         –
MQXF_XAPREPARE                       0000 –
MQXF_XACOMMIT                        0000 –

and the put options had _SYNCPOINT.

I had read documentation saying that you needed to have XAConnectionFactory instead of ConnectionFactory.  I could not get this work,  but found it was not needed for JMS;  it may be needed for JDBC.