Add 'car/' from commit 'eee0e8dc445691e600680f4abc77f2814b20b054'

git-subtree-dir: car
git-subtree-mainline: 1d29a5526c
git-subtree-split: eee0e8dc44

car/Messaging/mqttsession.py

@@ -0,0 +1,64 @@
+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
+
+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():
+    global client
+    if client is None or host is None:
+        print("Error: Client and/or host are not initialised.")
+    else:
+        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:
+        client.loop_stop()
+        client.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:
+        client =  mqtt.Client()
+
+    return client