EDIT

package eu.etaxonomy.cdm.vaadin.servlet;

import java.io.IOException;

import javax.servlet.ServletException;

import org.apache.log4j.Logger;

import com.vaadin.server.ServiceException;

import com.vaadin.server.SessionDestroyEvent;

import com.vaadin.server.SessionDestroyListener;

import com.vaadin.server.SessionInitEvent;

import com.vaadin.server.SessionInitListener;

import com.vaadin.server.VaadinServlet;

import com.vaadin.server.VaadinSession;

import eu.etaxonomy.cdm.api.conversation.ConversationHolder;

import eu.etaxonomy.cdm.vaadin.util.CdmSpringContextHelper;

import eu.etaxonomy.cdm.vaadin.util.DistributionEditorUtil;

public class CdmVaadinConversationalServlet extends VaadinServlet implements SessionInitListener, SessionDestroyListener {

	private static final Logger logger = Logger.getLogger(CdmVaadinConversationalServlet.class);

	private static final long serialVersionUID = -2973231251266766766L;

	private ConversationHolder conversation;

	@Override

	protected void servletInitialized() throws ServletException {

		super.servletInitialized();

		getService().addSessionInitListener(this);

		getService().addSessionDestroyListener(this);

	}

	@Override

	public void sessionInit(SessionInitEvent event)

			throws ServiceException {

		conversation = (ConversationHolder) CdmSpringContextHelper.getCurrent().getBean("conversationHolder");

		conversation.bind();

		VaadinSession.getCurrent().setAttribute(DistributionEditorUtil.SATTR_CONVERSATION, conversation);

	}

	@Override

	public void sessionDestroy(SessionDestroyEvent event) {

		conversation.close();

	}

	@Override

	protected void service(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws ServletException, IOException {

		if(conversation != null) {

			logger.info("Servlet Service call - Binding Vaadin Session Conversation : " + conversation);

			conversation.bind();

		}

		super.service(request, response);

	}

}