Calling Server side Event handler function Uisng Ajax Update pannel

1)Add Script manger to a page 2)Add Update panel in your page 3)Add any Server side standard Control . 4)In update panel call trigger tag .Inside trigger tag call asp:AysncPostBackTrigger control tag 5)Provide control id & eventname in above tag 6)Example below is assign Textbox value on buttin click

pseduocode aspx code //Asume one button control id="bttnAjax" and one textbox in content template of update pannel id=txtAjax"

<asp:UpdatePanel ID="UpdatePanel1" runat="server" >
<Triggers >
<asp:AsyncPostBackTrigger ControlID="bttnAjax" EventName="click"/>
</Triggers>
<ContentTemplate>
<asp:TextBox ID="txtAjax" runat ="server"/>
</ContentTemplate>
</asp:UpdatePanel>

Code Behind
protected void bttnAjax_Click(object sender, EventArgs e)

{

txtAjax.Text="Welcome To Ajax World "

}