How to download objects/files from server side

 WebClient client = new WebClient();

        Byte[] buffer = client.DownloadData(strPDFFileName);

        Response.ContentType = "application/pdf";

        Response.AddHeader("content-length", buffer.Length.ToString());

        Response.BinaryWrite(buffer);

(or)

From Memory Stream

   HttpContext.Current.Response.Buffer = true;

        HttpContext.Current.Response.ClearContent();

        HttpContext.Current.Response.ClearHeaders();

        HttpContext.Current.Response.ContentType = "application/pdf";

        HttpContext.Current.Response.AddHeader("Content-Disposition", "attachment;filename=" + strOutputFileName);

        HttpContext.Current.Response.BinaryWrite(MStream.GetBuffer());

        HttpContext.Current.Response.End();