Helper class for paho-mqtt to quickly integrate into existing sensor code (with reliable connection handling)

mqtt_helper.py

# Author: Skylar Sadlier 
# Author URL: https://github.com/skylord123
# Script Link: https://gist.github.com/skylord123/a54ce88aa79dfcd268a1cd92b499883d

import paho.mqtt.client as mqtt_client

# - Class Terminal -
# Uses curses to draw data to the terminal window.

class MQTT_Helper():
    def __init__(self, client_id='', host='', port=1883, username='', password='', keepalive=30, debug=False):
        self.client_id = client_id
        self.host = host
        self.port = port
        self.username = username
        self.password = password
        self.keepalive = keepalive
        self.active = False
        self.connected = False
        self.debug = debug
        self.topics = dict()

        """ Init the client """
        self.client = mqtt_client.Client(self.client_id)
        self.client.on_message = self.on_message
        self.client.on_publish = self.on_publish
        self.client.on_connect = self.on_connect
        self.client.on_disconnect = self.on_disconnect
        if(self.username != '' and self.password != ''):
            self.client.username_pw_set(self.username, self.password)

    def subscribe(self, ch, cb):
        if ch in self.topics:
            return False

        self.topics[ch] = cb
        # subscribe to topics
        if self.connected:
            self.client.subscribe(ch, 2)

        return True

    def on_message(self, client, data, msg):
        if self.debug:
            print("[MQTT RECEIVED] " + msg.topic + ": " + str(msg.payload))
        if msg.topic in self.topics:
            self.topics[msg.topic](msg)

    def exception_handler(self, request, exception):
        if self.debug:
            print("[MQTT ERROR]")
            print(vars(exception))
            print(vars(request))

    def on_publish(self, client, userdata, mid):
        if self.debug:
            print("[MQTT] PUBLISHED")

    def on_connect(self, client, userdata, flags, rc):
        if self.debug:
            print("[MQTT] CONNACK received with code %d." % (rc))
        self.connected = True
        for i in self.topics:
            self.client.subscribe(i, 2)

    def on_disconnect(self, client, userdata, rc):
        if self.debug:
            print("[MQTT] DISCON received with code %d." % (rc))
        self.connected = False
        self.active = False

    def publish(self, channel, message):
        if not self.connected and not self.active:
            self.connect();
        self.client.publish(channel, message)

    def connect(self):
        self.active = True
        self.client.connect(self.host, self.port, self.keepalive)
        self.client.loop_start()

    def disconnect():
        self.client.disconnect()
        self.client.loop_stop()

Example:

from classes.mqtt_helper import MQTT_Helper
import time

mqtt = MQTT_Helper('client_id', 'example.com', '1883')
mqtt.connect()

def test_event(msg):
	print msg.topic + ": " + msg.payload

mqtt.subscribe('test/test', test_event)

sup = 0
while True:
	try:
		sup += 1
		mqtt.publish("test/test2", "yo sup " + str(sup))
	except KeyboardInterrupt:
		print "Bye"
		GPIO.cleanup()
		sys.exit()