Lately I am focusing more and more on the Ajax.Net extenstions and framework in order to assimilate it wisely in my woring on web application. In general the .NET guys did here great job, created here realy a whole framework that includes new controls, namespaces etc... The outcome of it is good, it supplies us what we want doing it in quite easy way, there are nice webcasts, tutorials and lots of documentation that explains how to use it, but it's has also a (little?) disadventage - the actions' performance are quite bad in comparison to other open source tools, like Anthem.Net and more, you can impress of it here.

Until here is the post's intro... ;)

I investigated some the UpdateProgress control, it is nice one and supplies great usage and can gives us great UI results in a few minutes of simple actions. By investigating the source code of a web page that uses this control, I resolves this related code:

<script type="text/javascript">
<!--
Sys.Application.initialize();
Sys.Application.add_init(function() {
$create(Sys.UI._UpdateProgress, {"associatedUpdatePanelId":null,"displayAfter":500,"dynamicLayout":true}, null, null, $get<Update_Progress_Control_Client_ID>));
});
// -->
</script>

It's nice and being generated automatically of course, but what if you need to do some more actions while the callback action is under progress (you can think of tons client side actions, right?).

In this case I would suggest to abandon the UPdateProgress (great!) control and to implement this action by yourself in javascript using the Ajax client-side API, take a look of this one:

<script type="text/javascript">
    Sys.WebForms.PageRequestManager.getInstance().add_beginRequest(
        function ()
        {
            // Do your actions...        
        }
    );
    
    Sys.WebForms.PageRequestManager.getInstance().add_endRequest(
        function ()
        {
            // Do your actions...
        }
    );
</script>

Using the Sys.WebForms.PageRequestManager object, you can add/remove handlers to the Ajax client-side Life-Cycle events and do your stuff in a focused and single place -> much more easier to handle and to maintain.