How to use Ajax for FileUpload?

[thupham]

I use Visual Studio 2003, and Ajax.dll
In design, I have :
1 FileField, named: FileInput, set runnat="server"
1 Button (of Html toolbox), named: cmdUpload
1 Label (of HTML toolbox), named: lblInfo
First I create function for customer upload their file to server on click event:

[CODE=cpp]private void cmdUpload_Click (object sender, System.EventArg s e)
{
if (FileInput.Post edFile.FileName == "")
{
lblInfo.Text = "No file specified.";
}
else
{
try
{
if (FileInput.Post edFile.ContentL ength > 1048576)
{
lblInfo.Text = "File is too large.";
}
else
{
string fileName = Path.GetFileNam e(FileInput.Pos tedFile.FileNam e);
string filepath = Server.MapPath( "") +"\\bin\\Custom erPic\\"+fileNa me;
FileInput.Poste dFile.SaveAs(fi lepath);
lblInfo.Text = "File " + fileName + " uploaded.";
}
}
catch (Exception err)
{
lblInfo.Text = err.Message;
}
}
}[/CODE]
This function is successful, then I want to use Ajax when Customer click on cmdUpload, I don't set FileInput runnat="server" , so code behind can't see FileInput.
Can you give value of FileInput.PostF ile in code behind.
Or you can tell me other way to use ajax for FileUpload.
I hope to have true answer than other.
Thanks.