mqtt/__init__.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
"""
mqtt (MQTT)
===========

**Author:**

* Dirk Alders <sudo-dirk@mount-mockery.de>

**Description:**

    This Module supports functionality for mqtt connections

**Submodules:**

* :mod:`mqtt_client`

**Unittest:**

        See also the :download:`unittest <mqtt/_testresults_/unittest.pdf>` documentation.

**Module Documentation:**

"""

__DEPENDENCIES__ = []

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

try:
    from config import APP_NAME as ROOT_LOGGER_NAME
except ImportError:
    ROOT_LOGGER_NAME = 'root'
logger = logging.getLogger(ROOT_LOGGER_NAME).getChild(__name__)


class mqtt_client(object):
    def __init__(self, name, host, port=1883, username=None, password=None):
        self.__block_add_callbacks__ = False
        logger.info("Initiating mqtt client instance")
        self.__callbacks__ = {}
        self.__client__ = paho.Client(name)                                     # create client object
        if username is not None and password is not None:
            logger.debug("Configuring authentification")
            self.__client__.username_pw_set(username, password)                 # login with credentials
        self.__client__.on_message = self.__receive__                           # attach function to callback
        self.__client__.on_connect = self.__on_connect__
        self.__client__.on_disconnect = self.__on_disconnect__
        try:
            self.__client__.connect(host, port)                                 # establish connection
        except (socket.timeout, OSError) as e:
            logger.warning("Can not connect to MQTT-Server")
        self.__client__.loop_start()                                            # start the loop

    def add_callback(self, topic, callback):
        while self.__block_add_callbacks__:
            time.sleep(.1)
        logger.debug("Adding callback for topic %s", topic)
        self.__callbacks__[topic] = callback
        self.__client__.subscribe(topic)

    def send(self, topic, payload):
        self.__client__.publish(topic, payload)

    def __on_connect__(self, client, userdata, flags, rc):
        logger.debug("Connect with rc=%d", rc)
        if rc == 0:
            self.__block_add_callbacks__ = True
            logger.debug("Registering topics...")
            for topic in self.__callbacks__:
                self.__client__.subscribe(topic)
            self.__block_add_callbacks__ = False
 
    def __on_disconnect__(self, client, flags, rc):
        logger.warning("Disconnect with rc=%d", rc)

    def __receive__(self, client, userdata, message):
        logger.debug("Received message with topic %s and payload %s", message.topic, str(message.payload))
        for topic in self.__callbacks__:
            if topic.endswith('#'):
                if message.topic.startswith(topic[:-1]):
                    self.__callbacks__[topic](client, userdata, message)
            else:
                if topic == message.topic:
                    self.__callbacks__[topic](client, userdata, message)