Is there a quickstart example that uses EntityManager with transactions from a servlet ?

Issue

• We cannot find a quickstart example that uses EntityManager with transactions from a Servlet. Do I need to use a stateless Session Bean?
• How can we configure the EntityManager in a Servlet ?
• What is the difference in using @EJB and the CDI @Inject while injecting the Bean ?
• Is there any advantage of using the @Inject as oppossed to using the @EJB ?