I posted a very simple application on GitHub to help JEE beginners to grasp the main concepts of Java persistence by highlighting how to manipulate some basic operations. The application is in its version 1.0 but I am not planning to enrich it as it is not that important for me.
Link: https://github.com/begueradj/JPAlibSpringMVC
Link: https://github.com/begueradj/JPAlibSpringMVC