using update panel do sync job , update UI control async

Scenario :

1.click submit disable button ,start job 

2.once job done , enable submit button

Here is the implementation :

Aspx page Code :

Step 1: add update panel and script manager

<form id="form1" runat="server">

<asp:ScriptManager ID="ScriptManager" runat="server">
</asp:ScriptManager>
<asp:UpdatePanel ID="AsynUpdatePanel" runat="server" UpdateMode="Conditional">
<ContentTemplate>
<!--<span class="code-comment"> Here on click is a long running operation e.g. 30 secs --></span>
<asp:Button ID="Submit" runat="server"
OnClick="Submit_Click" Text="Submit" />

</ContentTemplate>
</asp:UpdatePanel>

</form>

Step 2: add javascript 

<script type="text/javascript">

Sys.WebForms.PageRequestManager.getInstance().add_beginRequest(startRequest);
Sys.WebForms.PageRequestManager.getInstance().add_endRequest(endRequest);

function startRequest(sender, e) {
document.getElementById("<%=Submit.ClientID%>").disabled = true;
}

function endRequest(sender, e) {
document.getElementById("<%=Submit.ClientID%>").disabled = false;
}

</script>

Step 3:

Code behind :

//Simulate a long time task

protected void Submit_Click(object sender, EventArgs e)
{
Thread.Sleep(2000);
}