We have seen several scenarios throughout this article that
discuss how to handle UserControls when AJAX is to be added to a website. One
would ask which scenario is best to follow. Well the normal answer would be it
depends on the situation you are experiencing. However, we do not like normal
answers and we would be strict in saying that, it is recommended to leave the
UserControls intact and add your AJAX controls to the host pages themselves.
Then you can either use Triggers or a programmatic call to update method of the
UpdatePanel for refreshing the content of any UpdatePanels.