Vaadin close UI of same user in another browser/tab/system

Question

I'm doing a project in Vaadin 7. In that I need to implement something like below for the login.

A user 'A' is logged in to a system '1'. And again he logs into another system '2'. Now I want to know how to close the UI on the system '1'.

I tried something and can able to close the UI, If it is the same browser. But, for different systems/browser. I don't have any idea.

My Code:

private void closeUI(String attribute) {
        for (UI ui : getSession().getUIs()) {
            if(ui.getSession().getAttribute(attribute) != null)
                   if(ui.getSession().getAttribute(attribute).equals(attribute))
                         ui.close();

            }
}

Can anyone help me in this?

Answer 1

I have a situation similar to your where I need to display several info regarding all sessions. What I did was I created my own Servlet extending the VaadinServlet with a static ConcurrentHashmap to save my sessions info, and a SessionDestroyListener to remove any info from the map upon logout. Initially I also had a SessionInitListener where I added the info in the hashmap but I realized I only had the user information after authentication so I moved this part to the page handling the login.

I guess you could do something similar, or at least this should get you started:

public class SessionInfoServlet extends VaadinServlet {

  private static final ConcurrentHashMap<User, VaadinSession> userSessionInfo = new ConcurrentHashMap<>();

  // this could be called after login to save the session info
  public static void saveUserSessionInfo(User user, VaadinSession session) {
    VaadinSession oldSession = userSessionInfo.get(user);
    if(oldSession != null){
      // close the old session
      oldSession.close();
    }
    userSessionInfo.put(user, session);
  }

  public static Map<User, VaadinSession> getUserSessionInfos() {
    // access the cache if we need to, otherwise useless and removable
    return userSessionInfo;
  }

  @Override
  protected void servletInitialized() throws ServletException {
    super.servletInitialized();
    // register our session destroy listener
    SessionLifecycleListener sessionLifecycleListener = new SessionLifecycleListener();
    getService().addSessionDestroyListener(sessionLifecycleListener);
  }

  private class SessionLifecycleListener implements SessionDestroyListener {
    @Override
    public void sessionDestroy(SessionDestroyEvent event) {
      // remove saved session from cache, for the user that was stored in it
      userSessionInfo.remove(event.getSession().getAttribute("user"));
    }
  }
}