A Add a second UpdatePanel to the page. Set it to trigger based on the first Update-Panel. Set the contents of this UpdatePanel to read “Processing, please wait.”
B Add an UpdateProgress control to the UpdatePanel. Set its DisplayAfter attribute to 5,000. Set its ProgressTemplate contents to read “Processing, please wait.”
C Add a ProgressBar control to the page. Write code on the server to call back to the client asynchronously to update the ProgressBar control after five seconds.
D Create a hidden <div> tag on your page that contains the text “Processing, please wait.” Set the <div> tag’s ID to match that of the UpdatePanel. Set the Update-Panel control’s Interval property to 5,000.