"""This module contains a class to create components to communicate with Snips
using the MQTT protocol directly.
.. note::
If you want to create a Snips app with access to an assistant's
configuration and a configuration for the app, you need to instantiate a
:class:`.MQTTSnipsApp` object, which is a subclass of
:class:`.MQTTSnipsComponent` and adds `assistant` and `config` attributes.
Example:
.. code-block:: python
from snipskit.mqtt.components import MQTTSnipsComponent
from snipskit.mqtt.decorators import topic
class SimpleSnipsComponent(MQTTSnipsComponent):
def initialize(self):
print('Component initialized')
@topic('hermes/hotword/toggleOn')
def hotword_on(self, topic, payload):
print('Hotword on {} is toggled on.'.format(payload['siteId']))
"""
import json
from paho.mqtt.client import Client
from snipskit.components import SnipsComponent
[docs]class MQTTSnipsComponent(SnipsComponent):
"""A Snips component using the MQTT protocol directly.
Attributes:
snips (:class:`.SnipsConfig`): The Snips configuration.
mqtt (`paho.mqtt.client.Client`_): The MQTT client object.
.. _`paho.mqtt.client.Client`: https://www.eclipse.org/paho/clients/python/docs/#client
"""
def _connect(self):
"""Connect with the MQTT broker referenced in the Snips configuration
file.
"""
self.mqtt = Client()
self.mqtt.on_connect = self._subscribe_topics
mqtt_options = self.snips.mqtt
host_port = mqtt_options.broker_address.split(':')
# Set up MQTT authentication
if mqtt_options.username and mqtt_options.password:
# The parameters mqtt_username and mqtt_password are both specified
# in the Snips configuration, so we use them for authentication.
self.mqtt.username_pw_set(mqtt_options.username,
mqtt_options.password)
# Set up an MQTT TLS connection
if mqtt_options.tls_hostname:
# Set up TLS.
self.mqtt.tls_set(ca_certs=mqtt_options.tls_ca_file,
certfile=mqtt_options.tls_client_cert,
keyfile=mqtt_options.tls_client_key)
host = mqtt_options.tls_hostname
else:
host = host_port[0]
port = host_port[1]
self.mqtt.connect(host, int(port), 60)
def _start(self):
"""Start the event loop to the MQTT broker so the component starts
listening to MQTT topics and the callback methods are called.
"""
self.mqtt.loop_forever()
def _subscribe_topics(self, client, userdata, flags, connection_result):
"""Subscribe to the MQTT topics we're interested in.
Each method with an attribute set by a
:func:`snipskit.decorators.mqtt.topic` decorator is registered as a
callback for the corresponding topic.
"""
for name in dir(self):
callable_name = getattr(self, name)
if hasattr(callable_name, 'topic'):
self.mqtt.subscribe(getattr(callable_name, 'topic'))
self.mqtt.message_callback_add(getattr(callable_name, 'topic'),
callable_name)
[docs] def publish(self, topic, payload, json_encode=True):
"""Publish a payload on an MQTT topic on the MQTT broker of this object.
Args:
topic (str): The MQTT topic to publish the payload on.
payload (str): The payload to publish.
json_encode (bool, optional): Whether or not the payload is a dict
that will be encoded as a JSON tring. The default value is
True. Set this to False if you want to publish a binary payload
as-is.
Returns: A :class:`paho.mqtt.MQTTMessageInfo` object.
"""
if json_encode:
payload = json.dumps(payload)
return self.mqtt.publish(topic, payload)