Styjun

I'm currently trying to use the paho mqtt library in Python3 in a object oriented context.
However, for some reason, the callback functions don't get called.

import paho.mqtt.client as mqtt
import time
import logging

logger = logging.getLogger("IDS_LOGGER.refining")
logging.basicConfig(level=logging.INFO)

class refiner(object):


def __init__(self,configpath="./sampleconfig.xml"):
 try:
 self.CONFIGPATH = configpath
 self.BROKER_IP = "localhost"

 self.parse_config()
 self.client = mqtt.Client()
 self.client.on_connect = self.on_connect
 self.client.on_message = self.on_message
 self.client.connect(self.BROKER_IP)
 logging.info("Connected to 0, starting MQTT loop".format(self.BROKER_IP))
 self.client.loop_forever()
 except Exception as e:
 print("error")


def on_message(self,client,userdata,msg):
 """MQTT Callback function for handling received messages"""
 print("message received!")


def on_connect(self,client,userdata,msg):
 print("connected!")
 self.client.subscribe("TRACED")

why?

Replace your on_connect() definition with:

def on_connect(self, client, userdata, flags, rc):
 print("connected!")
 self.client.subscribe("TRACED")

Also for debugging purposes, consider printing the actual exception in the exception handler instead of just printing "error":

 try:
 ...
 except Exception as e:
 print(e)

With the fixes above, I tested your code by connecting to test.mosquitto.org:

class refiner(object):

 def __init__(self):
 try:
 self.BROKER_IP = "test.mosquitto.org"
 self.client = mqtt.Client()
 self.client.on_connect = self.on_connect
 self.client.connect(self.BROKER_IP, 1883, 60)
 logging.info("Connected to 0, starting MQTT loop".format(self.BROKER_IP))
 self.client.loop_forever()
 except Exception as e:
 print(e)

 def on_connect(self, client, userdata, flags, rc):
 print("connected!")
 self.client.subscribe("TRACED")

x = refiner()

And it successfully outputs:

INFO:root:Connected to test.mosquitto.org, starting MQTT loop
connected!

I am Reading The Fine Docs.
They say you should:

def on_connect(client, userdata, flags, rc):
....
client = mqtt.Client()
client.on_connect = on_connect

Bbuuuttt, you didn't do that.
Within an OO class you have:

 def on_connect(self, client, userdata, msg):

Hmmm. Initially I thought that adding self was the problem, that your method would expect one more arg than paho provides when calling back.
But having written them both out, now I see that you turned flags, rc into msg, for reasons I cannot fathom.
I was thinking that somewhere behind the scenes paho might be logging a takes 5 positional arguments but 4 were given python error, but now it's unclear what happened.

In any event, you could finesse this detail and put the concern to rest with this code:

def on_connect(*args, **kwargs:
 with open('/tmp/log', 'a') as fout:
 fout.write('connected!n')

I avoided print() just in case sys.stdout is no longer connected to your shell terminal.

Consider using enable_logger at DEBUG level, and perhaps even the on_log callback.