Add on disconnect callback to mqtt example

Messaging/clientEx copy.py

@@ -18,14 +18,19 @@ def on_message(client, userdata, message):
     print("Received message '" + p + "' on topic '" 
     + message.topic + "' with QoS " + str(message.qos))
 
-mqttc = mqtt.Client()
+def on_disconnect(client, userdata, rc):
+    if rc != 0:
+        print("Unexpected disconnection.")
+
+mqttc = mqtt.Client(transport="websockets")
 
 # mqttc.tls_set_context(context = ssl.create_default_context())
 
 mqttc.on_connect = on_connect
+mqttc.on_disconnect = on_disconnect
 mqttc.on_message = on_message
 
-mqttc.connect('10.1.3.123', 1883, 60)
+mqttc.connect('iot.eclipse.org', 1883, 60)
 
 mqttc.loop_start()