This document discusses building a core application that can be deployed on different servers using a Java core. It provides examples using the Vaadin framework to build a basic application, deploying it on Apache Tomcat and IBM WebSphere Application Server. It also discusses setting up the application on IBM Domino using an OSGi plugin project. Additional topics covered include handling multiple authentication methods and implementing a data abstraction layer to make the application agnostic to the backend data store. The goal is to allow writing applications once and deploying them on any server with minimal changes.