Change to use external messaging module

DecisionSystem/CentralisedDecision/messenger.py

@@ -0,0 +1,133 @@
+import paho.mqtt.client as mqtt
+import json
+
+class Messenger:
+    _connect_callbacks = []
+    _disconnect_callbacks = []
+    _message_callbacks = []
+
+    def __init__(self):
+        pass
+
+    def broadcast_message(self, topic, message):
+        '''
+        Broadcasts the specified message to the swarm based upon its topic(or group).
+        '''
+        raise NotImplementedError
+
+    def unicast_message(self, target, message):
+        '''
+        Broadcasts the specified message to the single target.
+        '''
+        raise NotImplementedError
+
+    def connect(self):
+        '''
+        Connect to the swarm.
+        '''
+        raise NotImplementedError
+
+    def disconnect(self):
+        '''
+        Disconnect from the swarm.
+        '''
+        raise NotImplementedError
+
+    def add_connect(self, connect):
+        '''
+        Adds a callback to do something else once we are connected.
+        '''
+        self._connect_callbacks.append(connect)
+
+    def on_connect(self, code = None):
+        '''
+        Called once the messenger connects to the swarm.
+        '''
+        for cb in self._connect_callbacks:
+            cb(code)
+
+    def on_disconnect(self, code = None):
+        '''
+        Called when the messenger is disconnected from the swarm.
+        '''
+        for cb in self._disconnect_callbacks:
+            cb(code)
+
+    def add_disconnect_callback(self, on_disconnect):
+        '''
+        Adds a callback for when the messenger is disconnected.
+        '''
+        self._disconnect_callbacks.append(on_disconnect)
+
+    def add_message_callback(self, on_message):
+        '''
+        Adds a callback
+        '''
+        self._message_callbacks.append(on_message)
+
+    def on_message(self, message):
+        '''
+        Called when the messenger receives a message.
+        '''
+        for cb in self._message_callbacks:
+            cb(message)
+
+    @property
+    def id(self):
+        '''
+        The id for this messenger that is being used in communication.
+        '''
+        raise NotImplementedError
+
+    @property
+    def swarm(self):
+        '''
+        Gets the name of the swarm this instance is a part of.
+        '''
+        raise NotImplementedError
+    
+
+class MqttMessenger(Messenger):
+    '''
+    A messenger that uses MQTT.
+    '''
+    def __init__(self):
+        with open('config.json') as json_config:
+            self._cfg = json.load(json_config)
+
+        self._client = mqtt.Client()
+        self._client.on_connect = self.on_connect
+        self._client.on_message = self.on_message
+        self._client.on_disconnect = self.on_disconnect
+
+    def on_message(self, client, userdata, message):
+        Messenger.on_message(self, message)
+
+    def on_connect(self, client, userdata, flags, rc):
+        # Subscribe to the swarm specified in the config.
+        self._client.subscribe(self._cfg['mqtt']['swarm'])
+        Messenger.on_connect(self, rc)
+
+    def on_disconnect(self, client, userdata, rc):
+        Messenger.on_disconnect(self, rc)
+    
+    def broadcast_message(self, topic, message):
+        self._client.publish(topic, message, qos=1)
+
+    def connect(self):
+        self._client.connect(self._cfg['mqtt']['host'], \
+                            int(self._cfg['mqtt']['port']), \
+                            int(self._cfg['mqtt']['timeout']))
+
+        self._client.loop_start()
+
+    def disconnec(self):
+        self._client.disconnect()
+
+    @property
+    def id(self):
+        return self._client._client_id
+
+    @property
+    def swarm(self):
+        return self._cfg['mqtt']['swarm']