The BLE echo server does exactly what you think it does.
The echo server will accept the first BLE bonding request. Everything sent to the BLE 'websocket' service will be sent back. Checkout: ble_echo_server.js
Commands (replace 192.168.4.1 with the IP of your Fluxn0de):
curl http://192.168.4.1/control?setload=/ble_echo_server.js
curl http://192.168.4.1/control?reset
Now you should see Fluxn0de BLE advertisement packets.
Connect to the BLE service and start sending data.
If you have a BLE device that can query standard BLE services such as the battery service you should be able to get a reading from Fluxn0de.