I stuck amidst developing a chat web application using php for client side app. I used comet for chat application. And use technique of updating database when someone logout. Thus display offline on other side user. My problem is if someone close browser without logout, how the other side user know the person goes offline. How can i set online and offline icon in a php webchat application, when someone close chat window without logout? Is web sockets in php solve this problem? welcome all suggestions.