EDIT

import com.vaadin.server.ServletPortletHelper;

import com.vaadin.server.VaadinRequest;

import com.vaadin.server.VaadinService;

import com.vaadin.server.VaadinSession;

import com.vaadin.ui.UI;

import eu.etaxonomy.cdm.vaadin.server.CdmSpringVaadinServletService;

import eu.etaxonomy.cdm.vaadin.server.RequestEndListener;

import eu.etaxonomy.cdm.vaadin.server.RequestStartListener;

public abstract class AbstractEditorPresenter<DTO extends Object, V extends ApplicationView<?>> extends AbstractPresenter<V>

implements RequestEndListener, RequestStartListener {

    @Override

    protected void init(V view) {

        super.init(view);

        registerListeners();

    }

    @Override

    public void onViewExit() {

        super.onViewExit();

        unregisterListeners();

    }

    // -------------------------------------------------------------------------

    protected void registerListeners() {

     // register as request start and end listener

        VaadinService service = UI.getCurrent().getSession().getService();

        if(service instanceof CdmSpringVaadinServletService){

            logger.trace(String.format("~~~~~ %s register as request listener", _toString()));

            ((CdmSpringVaadinServletService)service).addRequestEndListener(this);

            if(logger.isTraceEnabled()){

                ((CdmSpringVaadinServletService)service).addRequestStartListener(this);

            }

        } else {

            throw new RuntimeException("Using the CdmSpringVaadinServletService is required for proper per view conversation handling");

        }

    }

    /**

    *

    */

   protected void unregisterListeners() {

       VaadinService service = UI.getCurrent().getSession().getService();

       if(service instanceof CdmSpringVaadinServletService){

           logger.trace(String.format("~~~~~ %s un-register as request listener", _toString()));

           ((CdmSpringVaadinServletService)service).removeRequestEndListener(this);

           if(logger.isTraceEnabled()){

               ((CdmSpringVaadinServletService)service).removeRequestStartListener(this);

           }

       } else {

           throw new RuntimeException("Using the CdmSpringVaadinServletService is required for proper per view conversation handling");

       }

   }

    /**

     * <b>ONLY USED FOR LOGGING</b> when Level==TRACE

     * {@inheritDoc}

     */

    @Override

    public void onRequestStart(VaadinRequest request){

        if(requestNeedsSession(request) ){

            if(getView() instanceof AbstractPopupEditor){

                Object bean = ((AbstractPopupEditor)getView()).getBean();

                getSession().merge(bean);

            }

        } else {

            // ignore hartbeat, fileupload, push etc

            logger.trace("ignoring request:" + request.getPathInfo());

        }

    }

    /**

     * Returns <code>true</code> for:

     * <ul>

     *   <li>..</li>

     * <ul>

     *

     * Return <code>false</code> for:

     *

     * <ul>

     *   <li>UILD request in a existing view, like clicking on a button</li>

     * <ul>

     *

     * @return

    protected boolean isActiveView(){

        return UI.getCurrent() != null && getView() != null && getView() == navigationManager.getCurrentView();

    }

     */

    @Override

    public void onRequestEnd(VaadinRequest request, VaadinSession session){

        if(requestNeedsSession(request) ){

            logger.trace("onRequestEnd() " + request.getPathInfo() + " " + _toString());

        } else {

            // ignore hartbeat, fileupload, push etc

            logger.trace("ignoring request:" + request.getPathInfo());

        }

    }

    /**

     * @param request

     * @return

     */

    protected boolean requestNeedsSession(VaadinRequest request) {

        return !(

                ServletPortletHelper.isAppRequest(request) // includes published file request

             || ServletPortletHelper.isFileUploadRequest(request)

             || ServletPortletHelper.isHeartbeatRequest(request)

             || ServletPortletHelper.isPushRequest(request)

             );

    }