WebWork

WebWork or Struts2 is a Java-based web application framework developed by OpenSymphony. It was developed with the specific intention of improving developer productivity and code simplicity. WebWork is built on top of XWork, which provides a generic command pattern framework as well as an Inversion of Control container.

WebWork provides robust support for building reusable UI templates, such as form controls, UI themes, internationalization, dynamic form parameter mapping to JavaBeans, robust client and server side validation, etc.

Reference:
http://en.wikipedia.org/wiki/WebWork