title: modular/pluggable java web application
body: <p>I have been trying to build a modular web application.  </p>
  
  <p>My requirements are to generate UI dynamically, but have the components of the ui be pluggable.  For instance I may have a core set of UI widgets that come out of the box, but if a client wanted to create there own there would be a defined interface for them to implement their own component.  </p>
  
  <p>I am using vaadin for my ui framework.  And would just like to have the end users provide a jar or war file that contains there ui.  I don't want to have to bundle the jar inside my war file however, whatever the end user provides should be deployable as is.  </p>
  
  <p>I have looked at using osgi, and have been able to get a framework that allows for dynamic ui from bundles using vaadin, however I am going through dependency hell with other req.  Are there other alternatives I haven't considered?</p>