Red Piranha uses Spring , a J2EE lite framework, for both it’s Presentation Layer (Spring MVC instead of an alternative like Struts) and for it’s mid tier.
I describe it as J2EE lite , as while it gives you most of the advantages of an EJB Server , it is a lot easier to deploy. It is also more flexible , allowing you to run your code in J2SE , then move to J2EE (either a Web Server like Tomcat , or a full application Server like JBoss , Weblogic or Websphere) when you are ready.
The article on how to get started with Spring is at: http://www.springframework.org/docs/MVC-step-by-step/Spring-MVC-step-by-step.html
Paul Browne 