class Broker:
"""
Respresents a connection to the MQTT broker.
"""
def __init__(self,
bot,
host=BROKER_HOST,
port=BROKER_PORT,
subscriptions=None):
"""
Create an instance and connect to broker.
:param bot: reference to the `Bot` instance.
:param host: the hoststring for the broker.
:param port: the port of the broker.
:param subscriptions: a dictionary in the form `topic name (string) => function to execute (callback)`. callback must be
able to receive three arguments - namely `client_id`, `userdata`, `message`.
"""
self._bot = bot
self._host = host
self._port = port
self._client = Client()
self._client.connect(self._host, self._port, 60)
self._subscribed_thread = None
if subscriptions:
self._subscribe(subscriptions)
def _subscribe(self, subscriptions):
from threading import Thread
def on_connect(client_id, userdata, flags, rc):
print('subscribed with code {}'.format(rc))
def listen():
for topic, callback in subscriptions.items():
self._client.callback(callback,
topic=topic,
hostname=self._host)
self._client.loop_forever()
self._client.on_connect = on_connect
self._subscribed_thread = Thread(group=None,
target=listen,
daemon=True)
self._subscribed_thread.start()
def _publish(self, topic, payload, qos=0):
# TODO: add json headers here
# msg = json.encode()
self._client.publish(topic, payload, qos=qos)
def send_message(self, topic, message):
"""
Send a text message to the broker.
:param topic: mqtt topic to which the message will be published.
:param payload: the message as string.
"""
self._publish(topic, message)
def send_file(self, topic, payload):
"""
Send a file to the broker.
:param topic: mqtt topic to which the message will be published.
:param payload: the binary content of the file.
"""
self._publish(topic, base64.encode(payload))