Configuring disconnected client notifications

To configure disconnected client notifications, you must configure Eclipse Amlen and a notification provider. You can use notification providers such as Worklight®, or you can create your own MQTT application to handle the notifications.

Configuring Eclipse Amlen for disconnected client notifications

To configure Eclipse Amlen for disconnected client notifications, you must create a topic policy that sets the DisconnectedClientNotification option to true. Any MQTT application that uses cleansession=0, and subscribes to a topic that is controlled by a messaging policy with DisconnectedClientNotification=True, is then monitored for disconnected client notifications.

For more information about configuring messaging policies, see Configuring message hubs.

Creating an MQTT application to receive disconnected client notifications

You can create an MQTT application to receive disconnected client notifications. The MQTT application must be configured to do the following things:

Connect to Eclipse Amlen using cleanSession=1
Subscribe to the reserved system topic: $SYS/DisconnectedClientNotification
Note: Applications are not permitted to create a shared subscription to the disconnected notification topic.
Process the published notifications. The notifications are published in JSON format, and include the user ID, client ID, and an array of topic strings and number of waiting messages. The following example shows a notification message for a client:
```
{ "ClientId":"MyPhone", "UserID":"Tom",
  "MessagesArrived": [
     { "TopicString":"/News/City/Austin", "MessageCount":"3" },
     { "TopicString":"/News/Breaking", "MessageCount":"1" }
  ]
}
```