This week's book giveaway is in the Mac OS forum. We're giving away four copies of a choice of "Take Control of Upgrading to Yosemite" or "Take Control of Automating Your Mac" and have Joe Kissell on-line! See this thread for details.
When the transaction setting in the config file (ejb-jar.xml) is "Container", the transactions are indeed managed by the container and as per spec's, commit and rollback statements are not to be used in code.
These are to be used only incase of Bean Managed Transaction, where in the transaction setting in ejb-jar.xml file would be "Bean".