MsgBox on server side - ajax

Question

I am trying to display a popup message on my web app. When i run my app normally on my local pc, i get the pop up message boxes appear. However when i publish the app they dont.
here's how it will work:
a button is pressed, it will pick up a file from a directory, then it will check another directory to see if the file the exists...if the file exists then a pop up is needed to inform "File already exists. do you want to continue?" if the user clicks yes it carried on with the code, if they click no then the process is ended.
do anyone have any idea how to do this?
my code so far:
If System.IO.File.Exists(acceptedExistsuNKNOWN) And System.IO.File.Exists(rejectedExistsUNKNOWN) Then
'IF BOTH EXIST
If MsgBox(acceptedExistsuNKNOWN & " & " & rejectedExistsUNKNOWN & "files already exists, do you want to rerun the process?", MsgBoxStyle.YesNo, "Files Exists") = MsgBoxResult.Yes Then
(continur
else
System.Diagnostics.Process.GetCurrentProcess.Kill()...
many thanks

Answer 1

The problem with your idea is that someone would need to sit logged in to the server to interact with the modal popup boxes; that is, if this was even possible, since it would need to be that person on the server who does the action on the page in order to be the recipient of the popup, so it's not like other users can issue a popup to him.
What you do on the server side executes on the server side.
I think you really want ti to show on the client side, but want the logic to make it happen on the server side. It doesn't work this way. Instead, what you might do is output something n the response that indicates a client-side popup should be shown. For instance, you could have a hidden field on the page and set a value, then use JavaScript to show an alert if that value meets your criteria.

Answer 2

Think about what you are asking. If a dialog pops on the server side, the user will not be able to see it (they are on the client side). Moreover, the code will be at a standstill until someone dismisses that dialog, which the user cant see. Only individuals with access to the server will be able to see this. Do you intend to have someone watching the server 24/7? Instead, you probably want to alert the user. This can be done my returning a response from the server code to the client code to display a dialog. The simplest method would be to throw an error and redirect the user to a new page to display an error. If you want something more fluid, you can use updated panels and the AjaxControlToolkit's modal pop up extender. Another way would be to use ClientScript, like this:
try
{
//check for files here
}
catch (Exception ex)
{
string script = "<script>alert('" + ex.Message + "');</script>";
if (!Page.IsStartupScriptRegistered("myErrorScript"))
{
Page.ClientScript.RegisterStartupScript("myErrorScript", script);
}
}