You can use the code in this tip to make web requests to a remote HTTP server and read the response:

try{   // The URL http://www.microsoft.com/en/us/default.aspx    // is used here purely as an example.   // Substitute your own URL as needed.   Uri uri = new Uri("http://www.microsoft.com/en/us/default.aspx");   System.Net.HttpWebRequest httpWebRequest =       (System.Net.HttpWebRequest)         System.Net.HttpWebRequest.Create(targetUri);   if ((httpWebRequest.GetResponse().ContentLength > 0))   {      System.IO.StreamReader str = new System.IO.StreamReader(         httpWebRequest.GetResponse().GetResponseStream());      Response.Write(str.ReadToEnd());      if (str != null) str.Close();    }}catch (System.Net.WebException ex){   Response.Write("File does not exist.");}