EWS streaming notifications are not received after some time

Question

I have a strange problem with the streaming events in EWS.

I have subscribed to a group of mailboxes using the needed cookies as mentioned here: https://msdn.microsoft.com/en-us/library/office/dn458789(v=exchg.150).aspx

After receiving notifications for some time, suddenly they stop to arrive ( usually after 40 minutes - 1 hour) I tried to debug it with the EWS trace and noticed that "heartbeat" messages that the exchange server sends periodically are no longer received, and example to this message:

<Envelope xmlns="http://schemas.xmlsoap.org/soap/envelope/">
<soap11:Header xmlns:soap11="http://schemas.xmlsoap.org/soap/envelope/">
  <ServerVersionInfo xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" MajorVersion="15" MinorVersion="1" MajorBuildNumber="1178" MinorBuildNumber="21" Version="V2017_04_14" xmlns="http://schemas.microsoft.com/exchange/services/2006/types" />
</soap11:Header>
<soap11:Body xmlns:soap11="http://schemas.xmlsoap.org/soap/envelope/">
  <m:GetStreamingEventsResponse xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages">
    <m:ResponseMessages>
      <m:GetStreamingEventsResponseMessage ResponseClass="Success">
        <m:ResponseCode>NoError</m:ResponseCode>
        <m:ConnectionStatus>OK</m:ConnectionStatus>
      </m:GetStreamingEventsResponseMessage>
    </m:ResponseMessages>
  </m:GetStreamingEventsResponse>
</soap11:Body>

I have set the OnDisconnect event to re-open the connection on timeout and saw that it works - so i guess its not a timeout problem.

Have anybody have a clue why the messages stop to arrive ?

Is the subscription is lost? should i re-subscribe ? (I didn't find any reference to this issue)

this is my code:

`static void ListenerFunciton()
{
// Set the exchange service
ExchangeService service = null;
service = new ExchangeService(ExchangeVersion.Exchange2013_SP1);
service.Url = new Uri("https://outlook.office365.com/EWS/Exchange.asmx");
service.Credentials = new WebCredentials(ServiceAccount, ServicePassowrd);
System.Net.ServicePointManager.ServerCertificateValidationCallback =
 delegate (Object obj, X509Certificate certificate, X509Chain chain, SslPolicyErrors errors)
 {
     return true;
 };

 string anchorMailbox = "blabla@domain.onmicrosoft.com"
 StreamingSubscription subsribption = null;

 //Set the coockies
 service.HttpHeaders.Add("X-AnchorMailbox", anchorMailbox);
 service.HttpHeaders.Add("X-PreferServerAffinity", "true");

 // Set the impersonation
 service.ImpersonatedUserId = new ImpersonatedUserId(ConnectingIdType.SmtpAddress, anchorMailbox);

 subsribption = service.SubscribeToStreamingNotifications(new FolderId[] { WellKnownFolderName.Inbox }, EventType.NewMail);

 int index = service.HttpResponseHeaders["Set-Cookie"].IndexOf("X-BackEndOverrideCookie");
 string coockie = service.HttpResponseHeaders["Set-Cookie"].Substring(index).Split(';')[0];
 service.HttpHeaders.Add("Cookie", coockie);

 StreamingSubscriptionConnection connection = new StreamingSubscriptionConnection(service, 29);
 connection.AddSubscription(subsribption);
 connection.OnNotificationEvent += OnNotificationEvent;
 connection.OnDisconnect += OnDisconnect;
 connection.Open();
 while(true)
 {

 }

}

static private void OnDisconnect(object sender, SubscriptionErrorEventArgs args)
{
    Console.WriteLine("\n\n\n\nFrom now this is the reconnection\n\n\n\n");
    //cast the sender object
    StreamingSubscriptionConnection connection = (StreamingSubscriptionConnection)sender;
    //reconnect
    connection.Open();

}

static private  void OnNotificationEvent(object sender, NotificationEventArgs args)
{
    file.WriteLine(DateTime.Now.ToString() + " || Got notification");
    file.Flush();
    foreach (NotificationEvent notification in args.Events)
    {
        file.WriteLine("From Subscription: "+args.Subscription.Id+" Event: "+notification.EventType.ToString("D"));
        file.Flush();
    }
    file.WriteLine("\n\n");
}`

Answer 1

StreamingSubscriptionConnection has life time is 1-30, so after life time min Stream open connect, raise events and close connection.