Why does HttpWebRequest fail the first time and then works OK?

Question

I am truing to integrate fusemail in asp.net 2.0. I am using HttpWebRequest for requesting the API pages. It has recently come to my notice that HttpWebRequest fails the first time and then continues and subsequent requests succeed.

say ( i know if i use goto it is a bad programming approach) if i use this code

retry:
        try
        {
            Uri uri = new Uri("http://www.fusemail.com/api/request.html");
            if (uri.Scheme == Uri.UriSchemeHttp)
            {

                HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(uri);
                request.PreAuthenticate = true;
                request.Method =
                WebRequestMethods.Http.Post;

                //request.ReadWriteTimeout = System.Threading.Timeout.Infinite;
                //request.Timeout = System.Threading.Timeout.Infinite;
                request.ContentLength = data.Length;
                request.ContentType =
                "application/x-www-form-urlencoded";
                //request.UserAgent = Request.UserAgent;
                request.UserAgent = "Mozilla/4.0";
                request.KeepAlive = false;

                request.ServicePoint.Expect100Continue = true;
                //request.Accept = "Accept: text/html,application/xhtml+xml,application/xml";


                StreamWriter writer = new StreamWriter(request.GetRequestStream());
                writer.Write(data);
                writer.Close();

                HttpWebResponse response = (HttpWebResponse)request.GetResponse();

                StreamReader reader = new StreamReader(response.GetResponseStream());
                string tmp = reader.ReadToEnd();
                response.Close();
                //Response.Write(tmp);

                if (!String.IsNullOrEmpty(tmp))
                {
                    return tmp;
                }
            }
            return String.Empty;
        }
        catch (WebException ex)
        {

            goto retry;
        }

it works after failing once. i am writing to a text file in case of an error and after i failed request it works the second time. I am using ASP.Net 2.0 and the website is hosted on IIS 7 with Windows Server 2008 Standard. Also pinging the API address it fails the first time and then responds

C:\>ping 67.207.202.118

Pinging 67.207.202.118 with 32 bytes of data:
Reply from 192.168.0.253: **Destination host unreachable**.
Reply from 67.207.202.118: bytes=32 time=218ms TTL=49
Reply from 67.207.202.118: bytes=32 time=218ms TTL=49
Reply from 67.207.202.118: bytes=32 time=217ms TTL=49

Ping statistics for 67.207.202.118:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 217ms, Maximum = 218ms, Average = 217ms

The first time it fails in HttpWebRequest it fails with this error

System.Net.WebException: Unable to connect to the remote server ---> System.Net.Sockets.SocketException: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond 67.207.202.118:80

Is there an authentication issue the first time?. i read on some forums it first sends a 401 Unauthorized and then it can connect. I am unable to verify this using Fiddler.

Is there anything wrong with IIS configuration?

Answer 1

This is not a programming issue at all, I have faced a similar problem later and it was a network configuration problem due to ISA server / Firewall settings. You have to contact your network administrator to check this issue.

I wish this helped you.

Yours,

Mohamed Kamal Elbeah

Senior .Net Developer