This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
"resource-local Entity Manager" are used outside to the Java EE container. As an example if we are dealing with a swing application, JTA is not a possibility. So resource-local transactions are used in this case. So implementation of EntitTransaction interface is required.