You can specify that the NexJ application server use streaming or push notifications to receive updates from user folders on Exchange Server.

Streaming notifications
The NexJ application server subscribes to a folder on Exchange Server and opens a streaming connection. Notifications are received by the NexJ application server as a response on that connection. You must enable the Autodiscover service to use streaming notifications.
Push notifications
The NexJ application server subscribes to a folder on Exchange Server and provides a callback URL, for example https://<host>/nexj/anon/channel/ExchangeEWSNotificationReceiver, for Exchange Server. When user folders are updated, Exchange Server posts a notification to the NexJ application server.

Specifying notification communication methods

You can enable streaming or push notifications for Exchange Server 2013 and Exchange Server 2016 in NexJ Admin Console.

Before enabling the streaming communication method, you must specify the URL for the Exchange Server target in the ExternalEwsUrl property on Exchange Server 2013 or Exchange Server 2016.

To specify the notification communication method for an Exchange server:

1. In NexJ Admin Console, navigate to the Synchronization page.
2. In the Synchronization tab, select an exchange server in the Targets list.
3. In the Exchange Server EWS zone, click the Edit button  on the top right of the page.
   The Edit Exchange Server dialog opens.
4. In the Version field, ensure that Exchange 2013 or Exchange 2016 is selected.
5. In the Subscription Type field, select Streaming or Push.
6. Click OK.
   The Edit Exchange Server dialog closes.

You have enabled streaming or push notifications for the selected Exchange server. If you enabled streaming notifications, note that subscriptions to user folders do not occur immediately. User folders become subscribed as follows:

1. The Autodiscover service runs and obtains grouping information for links to user folders.
2. Links to user folders subscribe on a periodic timer.
3. Subscribed links are placed on a queue and wait to be streamed.
4. Messages on the queue are processed and a streaming connection is opened for all links in that message.

You can view the subscription status of individual users folders in the Subscription State field in the Links list at the bottom of the Synchronization page.

Viewing the subscription status of user folders

You can view information about links to user folders for a target server in the Links list at the bottom of the Synchronization page. Statuses vary depending on whether push or streaming notification communication method is used.

To view the subscription status of a user folder:

1. In NexJ Admin Console, navigate to the Synchronization page.
2. In the Links list at the bottom of the page, select a user folder. The following information displays in the details section at the right of the Links list in the Subscription state field.
   

   Subscription state
   The subscription state of a user folder that receives notifications from Exchange Server. The following states are available for folders that use the push notification communication method.
   Waiting to subscribe
   The folder does not have an active subscription and is waiting to subscribe with the next subscription batch job.
   Subscribed
   The folder is subscribed and is waiting for notifications to arrive from Exchange Server.
   Disabled
   Inbound synchronization is disabled for the folder.
   The following states are available for folders which use the streaming notification communication method.
   Waiting for autodiscover
   Grouping information has not yet been obtained from the Autodiscover service. The NexJ application server requires grouping information to subscribe a user folder.
   Waiting to subscribe
   Grouping information has been obtained from the Autodiscover service and the folder is waiting for the subscription batch job to subscribe the folder.
   Queueing to stream
   A subscription ID has been obtained from Exchange Server and is being queued to open the streaming connection.
   Streaming
   A streaming connection is open for this folder and the folder is listening for changes.
   Disabled
   Inbound synchronization is disabled for the folder

3. Close the Synchronization page.

You have viewed the subscription status of a user folder.