When you synchronize data in an offline application, you might want to let the user know immediately if synchronization is currently not possible - because the server is not available, or because there is no internet connection rather than waiting for the Ajax callback to fail after it times out. Also, if there is an available internet connection, but the connection is slow, you might want to prevent the user from synchronizing and you might want to display a message telling the user to try again later when there is a faster connection.

In this video we show how this can be done.