With the release 5.2.0 the OLAT GUI can be served in two different modes. The "normal" and the "AJAX" mode. In the normal mode every page that is requested from the server gets delivered as a fully rendered HTML page with complete header and body. In the ajax mode only the components in the screen that changed are delivered to the client and displayed by dom replacement. The administration menu item "AJAX" shows which clients are fully tested and support the ajax mode. The clients are checked by the html header attribute "user-agent". You can add other user agent stings here for immediate activation. But if you want them permanent ajax activated you have to add them to the olat-config.xml file.

When the ajax mode is activated each client starts polling in periodical time. This feature is at the moment mainly used in the instant messaging stuff either for indicating that the user has a new message or while chatting. Default polling time is 10s and 2s while chatting. To increase or decrease this value see section instant messaging in the admin environment.