DataSource Controls :: Export Data Of Sqldatasource To Exel And Save It In Specific Location?

I have a code that read all data from sqldatasource and store it in exel file. my problem is,when the program run when i click on button,the message pop up to open or save, so by click on open or save we can either save it in exel file or open and look in exel file.

i want withought poping any message,it store the file directly to the specific folder without infomring the user.

here is my code

string attachment = "attachment; filename=Contacts.xls";

Response.ClearContent();
Response.AddHeader("content-disposition", attachment);
Response.ContentType = "application/ms-excel";
StringWriter sw = new StringWriter();
HtmlTextWriter htw = new HtmlTextWriter(sw);
GridView1.RenderControl(htw);
Response.Write(sw.ToString());
Response.End();