"gaohoward" wrote : in JMS, the producer and consumer are separate. So you are free to define a transaction boundary for the messages regardless the producer side. | Hopefully my answer to ataylor makes what i want to do a bit clearer. I know it is possible to define the transaction boundary consumer-side (you need to use BMT in you MDB). But since in my example the 2 onMessage executions would happen in a different thread, wouldn't it be impossible for them to happen in the same transaction? "gaohoward" wrote : | don't quite understand your second question, can you explain it a bit more? | For instance can 2 onMessages (different threads) execute in a single transaction? View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4253605#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...