Notifications with cron job


In my application, I want to display notification to the user according to the cronjob(periodically) ,In vaadin we can use Notification and the PopView for this , but seems like its not working as I expected(It does not display the notification or popup according to the cronjob,user have to click UI to display the notification) , I have another requirement. Notification should display until user click on the notification,when use click on the notification, System should popup the window with notification information, Is there any component which I can use for this in Vaadin

Thank you