anonymous wrote : 1) How important is it to have JBoss infrastructure use the DefaultDS while applications use something else? (Stated in another way, what advantage does this configuration provide?) As Peter rightly mentioned, using just a single database to host everything (= server's data and your app's data) isn't the right thing since that data is not related to each other. anonymous wrote : 2) Is this a supported (as in tried and tested, not as in paid support) configuration using MySQL and JBoss 5.0? Yes MySQL datasource works against JBossAS-5.0 anonymous wrote : | 3) Is there really a need to use XA data sources when one source is for JBoss infrastructure and the other is for my application? You mentioned that you ran into Multiple 1PC exception. Can you post that entire exception stacktrace? And when do this happen? Does it happen in a transaction where you trying to use your app's datasource (to save something to DB) and in the same transaction, send a message JMS message to queue/topic? In that case you are involving 2 transaction aware resources - one is your app's datasource and one is the datasource of JMS (used for message persistence). If you don't want them to be part of the same transaction, probably you can break them into different transactions. View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4225657#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...