I did some testing but never managed to get an application's response message in one of the node's receive windows. Instead, it always seems to be queued for the next uplink message...
So, should the following be feasible in the real world?
- Class A node sends uplink message.
- Application server, which has subscribed to TTN back end using MQTT, receives uplink message notification and immediately prepares response message.
- Application server publishes response message to TTN using MQTT within 1 second of uplink message reception notification.
- Response message is transmitted as downlink message to the node in one of the two receive windows of the uplink message.