GWT hit HTTP servlet with RequestFactory

I want to use GWT's RequestFactory for all client-server communication, if possible. My understanding is that you have to map /gwtServlet to RequestFactoryServlet in your web.xml, and then use @Service annotations to tell the RequestFactoryServlet how to map client-side requests to their appropriate services.

Can someone provide a complete code example of this process, both on the client- and on the server-side? I'd like to send a Widget object from the client side to a WidgetProcessor service on the server-side:

public class Widget {
    // This is a domain object (POJO).
}

public class WidgetProcessor {
    public void processWidget(Widget w) {
        // Inspect the Widget. If certain properties contain certain
        // values, place it on a queue. Else "process" the Widget
        // and persist it to a DB.

        if(w.containsSpecialValues())
            QueueManager.sendToQueue(w);
        else {
            // Process widget...

            WidgetDAO.save(w);
        }
    }
}

In a non-GWT context, I would just define a WidgetProcessorServlet, map it to /processWidget, and make it look like:

@Override
public void doGet(HttpServletRequest request, HttpServletResponse response) {
    WidgetProcessor widgetProcessor = new WidgetProcessor();
    widgetProcessor.processWidget(getWidgetFromRequest(request));
}

How does this work in RequestFactory-land? Thanks in advance.