frontcontroller or ActionServelt or preprocessor all are same,because ActionServelt is one which is the Controller in Struts based Application

ActionServlet of Struts is part of Controller components which works as front controller to handle all the requests.

ActionServlet provides the "controller" in the Model-View-Controller (MVC) design pattern for web applications that is commonly known as "Model 2". It is backbone of struts application.It is used as controller to control .There can be only one ActionServlet defined for a context. ActionServlet is defined in web.xml file of a context e.g. WEB-INF/web.xml


Thanks.