Add methods for callbacks to the mqtt client.

Messaging/mqttsession.py

@@ -1,11 +1,28 @@
 import paho.mqtt.client as mqtt
 
+"""
+Wrapper module for paho mqtt library, providing a singleton instance of the client to be used.
+Also adds some convenience functions such as having multiple connected callbacks,
+and managing whether the client is still connected. 
+"""
+
+
 client = mqtt.Client()
 host = None
 
-"""
-Wrapper module for paho mqtt library, providing a singleton instance of the client to be used. 
-"""
+connect_callbacks = []
+disconnect_callbacks = []
+
+def on_connect(client, userdata, flags, rc):
+    print("Connected with result code " + str(rc))
+    if rc == 0:
+        global connected
+        connected = True
+
+    for callback in connect_callbacks:
+        callback()
+
+    client.subscribe('hello/test', qos=1)
 
 # Arguably not needed, just want to make the client static, but here anyway.
 def connect():
@@ -16,6 +33,14 @@ def connect():
         client.connect(host, port=1883, keepalive=60, bind_address="")
         client.loop_start()
 
+def add_connect_callback(callback):
+    global connect_callbacks
+    connect_callbacks += callback
+    connectted = True
+
+def add_disconnect_callback(callback):
+    global 
+
 def disconnect():
     global client
     if client is not None:
@@ -24,6 +49,13 @@ def disconnect():
     else:
         print("Error: Client is not initialised.")
 
+def on_disconnect(client, userdata, rc):
+    if rc != 0:
+        print("Unexpected disconnection.")
+
+    global connected
+    connected = False
+
 def Client():
     global client
     if client is None: