Hi,

I'm using the NotificationSampleWebDAV provided with Exchange SDK to moniter
the MailBox over the excange server and process the inbox messages when ever
new mail comes.Here I'm using the Subscribe and Poll methods of
WebDavAccessor. I'm using the application as it is, but the problem is that
when I run the application continuoulsy for more then 20 min,  I'm getting
the following error

Warning: Exiting Action with an exception: The remote server returned an
error: (440) Login Timeout.
Stack Trace for the excetion:    at
System.Net.HttpWebRequest.CheckFinalStatus()
  at System.Net.HttpWebRequest.EndGetResponse(IAsyncResult asyncResult)
  at System.Net.HttpWebRequest.GetResponse()

After through investigation i found that the server is creating the
SessionId and the session is expiring after 20 minutes.

I want to have the continues access to the exchange server.

Can any body help me to resolve this issue.

The code that I'm using is as follows,

static private string Action(string Uri, string Method, string
NotificationType, string SubscriptionID)
        {
           // Declare variables.
            string XmlData = "";  
            Request = null;
            byte[] bytes = null;
           WebResponse requestResponse = null;
            string Body = "";
            NetworkCredential mycred = new
System.Net.NetworkCredential(Username,Password,Domain);
           
            try
            {   
                //accept ssl certificate
                ServicePointManager.CertificatePolicy = new AcceptAllCertificatePolicy();

                //do form-based authentication
                if (AuthCookies==null)
                {
                    AuthCookies = DoFormbasedAuthentication(Uri, mycred);
                }

           
                // Create a new credentials cache.
                System.Net.CredentialCache MyCredentialCache = new
System.Net.CredentialCache();

                // Add user name, password, and domain to the credentials cache and use
NTLM authentication.
                MyCredentialCache.Add(new Uri(Uri),"Basic", new
System.Net.NetworkCredential(Username,Password,Domain));
               
                //accept ssl certificate
                ServicePointManager.CertificatePolicy = new AcceptAllCertificatePolicy();

                // Create request object and assign credentials.
                Request = (System.Net.HttpWebRequest) HttpWebRequest.Create(Uri);
                Request.CookieContainer = new CookieContainer();
               
                // Set the WebRequest credentials property to the credentials cache.
                Request.Credentials = MyCredentialCache;
               

               if (AuthCookies.Count == 2)
                {
                    Request.CookieContainer.Add(AuthCookies);
                }
                else
                {
                    throw new ApplicationException("Authentication cookies not set.");
               
                }
                switch(Method)
                {
                    case "UNSUBSCRIBE":
                        Request.Method = "UNSUBSCRIBE";
                        Request.Headers.Add("subscription-id",SubscriptionID);
                        break;

                    case "POLL":
                        Request.Method = "POLL";
                        Request.Headers.Add("subscription-id",SubscriptionID);
                        break;

                    case "SUBSCRIBE":
                        Request.Method = "SUBSCRIBE";
                        Request.Headers.Add("Notification-type",NotificationType);
                        Request.Headers.Add("Subscription-lifetime","12000");
                        if(SubscriptionID != "0" && SubscriptionID != "-1")
                        {
                            Request.Headers.Add("subscription-id",SubscriptionID);
                        }
                        Request.Headers.Add("Depth","1");
                        break;
                    case "SEARCH":
                        Request.Method = "SEARCH";
                        //retrieve subject and href for all emails that have an
                        //attachment
                        Body = "<?xml version=\"1.0\"?><D:searchrequest xmlns:D = \"DAV:\" >"
                            + "<D:sql>SELECT \"urn:schemas:httpmail:subject\" FROM \"" + Uri + "\""
                            + "WHERE \"DAV:ishidden\" = false AND \"DAV:isfolder\" = false"
                            + " AND \"urn:schemas:httpmail:hasattachment\" = true"
                            + "</D:sql></D:searchrequest>";

                        Request.ContentType = "text/xml";
                        //Request.Headers.Add("Brief","t");
                        break;
                    case "X-MS-ENUMATTS":
                        Request.Method = "X-MS-ENUMATTS";
                        //Request.Headers.Add("subscription-id",SubscriptionID);
                        Body = "<?xml version=\"1.0\" ?><NoResponse></NoResponse>";
                        Request.Headers.Add("Depth","1,noroot");
                        Request.ContentType = "text/xml";
                        break;
                    case "DELETE":
                        Request.Method = "DELETE";
                        Request.Headers.Add("Depth","infinity");
                        Request.ContentType = "text/xml";
                        break;

                    default:
                        Trace.WriteLine("Warning: Case missed in Action method");
                        Request.Method = Method;
                        Request.Headers.Add("translate","f");
                        Request.ContentType = "text/xml";
                        Request.Headers.Add("Overwrite","t");
                        break;
                }

                // The SUBSCRIBE, POLL, AND UNSUBSCRIBE methods do not
                // require a method request body.
               

                // Encode the body using UTF-8.
               
                    bytes = Encoding.UTF8.GetBytes((string)Body);

                // Set the content header length.
                Request.ContentLength = bytes.Length;
                try
                {

                    Stream newStream = Request.GetRequestStream();
                    newStream.Write(bytes, 0, bytes.Length);

                    newStream.Close();
                }
                catch(Exception ex)
                {
                    Trace.WriteLine("Stact Trace:" + ex.Message +"---"+ ex.StackTrace);
                }

               
            }

           // If the server is not available, the exception will be caught
here.
            catch(Exception ex)
            {
               Trace.WriteLine("Exiting Action with an EXCEPTION when
handling stream: " + ex.Message);
                Trace.WriteLine("Stack Trace: " + ex.StackTrace);
                throw ex;
            }

           try
           {
                  // Call the method and get the response from the server.
               requestResponse = Request.GetResponse();
               if (requestResponse.ContentLength == 0)
               {
                   LastInterpretedResult = (bool)false;
               }

               try
               {
                   // Get the subscription ID.
                   LastSubscriptionID =
requestResponse.Headers.Get("Subscription-ID");
                   if (LastSubscriptionID == null)
                   {
                   LastSubscriptionID = "0";
                   }
               }
               catch
               {
                   // If the SUBSCRIBE method is not being called, then set
LastSubscriptionID
                   // to zero.re
                    LastSubscriptionID = "0";
               }

                // Get returned XML stream.
                Stream ReceiveStream = requestResponse.GetResponseStream();

                //set response stream on object
                LastResponseStream = ReceiveStream;
               

                // Get the utf-8 encoding object.
                Encoding encode = System.Text.Encoding.GetEncoding("utf-8");
                StreamReader sr = new StreamReader( ReceiveStream, encode );

                // Read the XML to the end.
                XmlData = sr.ReadToEnd();

               if (XmlData.IndexOf("412 Precondition Failed") > 0)
               {
                   // The POLL method failed.
                   LastSubscriptionID = "-1";
               }

                if (XmlData.IndexOf("Operation timed-out") > 0)
                {
                    LastSubscriptionID = "-1";
                }

                if (XmlData.IndexOf("(440) Login Timeout.") > 0)
                {
                    LastSubscriptionID = "-1";
                }

               if (XmlData.IndexOf("200 OK") > 0)
               {
                   // The WebDAV method succeeded.
                   LastInterpretedResult = (bool)true;
                   LastPollResult = (int)LastPollEnum.NotifyTrue;
               }
               else
               {
                   if (XmlData.IndexOf("No Content") > 0)
                   {
                       LastPollResult = (int)LastPollEnum.NoFolder;
                   }
                   else
                   {
                       LastPollResult = (int)LastPollEnum.NotifyFalse;
                   }
                   LastInterpretedResult = (bool)false;
               }

           }
           catch (Exception ex)
           {
               // A few of the most important and common errors. For more
detail see the
               // SDK documentation.
               //
               // 403 - Forbidden - This means there is not enough access
to create this folder.
               // 405 - Method not allowed - This can mean the user is
overwriting a folder (among
               // other things).
               // 404 - Not found -  This is often used to find out if
something exists.
               // 505 - Server unavailable.
               // 500 - Internal Server Error

               // Throw a clean version of the internal server error.
               if (XmlData.IndexOf("500 Internal Server Error") > 0)
               {
                    throw new ApplicationException("An internal server
error occured, unable to complete request.");
               }

                if (XmlData.IndexOf("Operation timed-out") > 0)
                {
                    LastSubscriptionID = "-1";
                }

                if (XmlData.IndexOf("(440) Login Timeout.") > 0)
                {
                    LastSubscriptionID = "-1";
                }

               Trace.WriteLine("Warning: Exiting Action with an exception:
" + ex.Message );
                Trace.WriteLine("Stack Trace for the excetion: "  + ex.StackTrace );
                //Trace.WriteLine("{0}"+ ex.InnerException);
                Trace.WriteLine("{0}",ex.Source);

               throw ex;
           }

           // Close the response object.
           requestResponse.Close();
           
           // Get the XML response from the WebDAV method call.
           LastResponseXML = XmlData;

            return XmlData;
        }
        // End of Class.
    }

static private CookieCollection DoFormbasedAuthentication(string uri,
NetworkCredential mycred)
        {
            string server;
            HttpWebRequest request;
            HttpWebResponse response;
            byte[] body;
            Stream stream;
            //string result;
           try
           {
               // Get the server portion of the requested uri and appen the
authentication dll from Exchange

               server = uri.Substring(0, uri.IndexOf("/", 8)) +
"/exchweb/bin/auth/owaauth.dll";

               request = GetRequestObject(server, "POST");
               request.CookieContainer = new CookieContainer();
                request.ContentType = "application/x-www-form-urlencoded";
              // Prepare the body of the request
            body =
Encoding.UTF8.GetBytes(string.Format("destination={0}&username={1}\\{2}&password={3}",uri, mycred.Domain, mycred.UserName, mycred.Password));
                    request.ContentLength = body.Length;
                    // Send the request to the server
                    stream = request.GetRequestStream();
                    stream.Write(body, 0, body.Length);
                    stream.Close();
                    // Get the response
                    response = (HttpWebResponse)request.GetResponse();
                    // Check if the login was successful
                    if (response.Cookies.Count < 2) throw
                    new  ApplicationException("Failed to login to OWA. Be sure your domain
and password are correct.");
                    return response.Cookies;
                }
                   catch (ApplicationException ex)           
                {           
                    throw ex;
                }
                catch (Exception ex)
                {
                    throw new Exception("Failed to login to OWA. Username =" +
mycred.UserName + " Password =" + mycred.Password + " domain = " +
mycred.Domain + ".The following error occured: " + ex.Message, ex);
                }
 }

Thanks in advance,
Vijay G