I got acquainted with Apache TomEE (http://tomee.apache.org) a while ago when asked to do a proof of concept for a web application. The vision for the application was: built on top of open source solutions, very scalable and capable of easy integration with legacy applications. 

 Having been a member of the technical cabinet for the organization I work for, one of my concerns is always checking out the new trends for SW development. So, for the choice of the web server I did some digging and come across Apache TomEE.

 Tomcat is one of the most widely spread servers (even Heroku provides it as the default container for Java). But, up to TomEE it didn’t cover the so craved EE features like JPA, EJB, CXF or JMS. The plus side is that Tomcat is as easy as it gets (at least for old java enthusiasts, who like xml config files!). 

 So I gave it a try:

Resources like DBs are configured in tomeeDir/conf/tomee.xml

Java Persistence properties are setup as expected on your 

WEB-INF\classes\META-INF\presistence.xml

That being said, it's possible to quickly put in place a simple architecture, with low demand for resources and highly scalable. (The other components weren’t picked by chance, but that would be another post J.)