Redirect the flow from servlet to portlet

[silicio]

Hi all,
I'm using JBoss AS 4.0.4GA + JBoss Portal 2.4 Beta1.
I've to redirect from a servlet to a portlet, but I don't know how. I always get a 500 error:

2006-07-04 18:08:50,171 INFO [org.apache.catalina.core.ContainerBase.[jboss.web].[localhost].[/myportal]] Marking servlet centralController as unavailable
2006-07-04 18:08:50,171 ERROR [org.apache.catalina.core.ContainerBase.[jboss.web].[localhost].[/myportal].[centralController]] Allocate exception for servlet centralController
java.lang.ClassCastException: mywork.controllers.CentralController
 at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1055)
 at org.apache.catalina.core.StandardWrapper.allocate(StandardWrapper.java:757)
 at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:641)
 at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:574)
 at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:499)
 at mywork.utility.uploadfile.UploadFile.service(UploadFile.java:130)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:810)

My flow is PORTLET --> JSP --> SERVLET --> PORTLET

I've tried mapping portlet class into web.xml file without succes.

here's the code within the servlet (note that sc is the ServletContext):

request.setAttribute("azione",String.valueOf(Costanti.UPLOAD_FILE));
rd = sc.getRequestDispatcher("/controller/CentralController");
rd.include(request,response);

here's relative web.xml part:

<servlet>
 <servlet-name>centralController</servlet-name>
 <servlet-class>mywork.controllers.CentralController</servlet-class>
</servlet>

<servlet-mapping>
 <servlet-name>centralController</servlet-name>
 <url-pattern>/controller/CentralController</url-pattern>
 </servlet-mapping>