MQTT bundle for AppLauncher

MQTT support for applauncher

Installation

pip install mqtt_bundle 

Then add to your main.py

import mqtt_bundle

bundle_list = [
    mqtt_bundle.MqttBundle(),
]

Configuration

mqtt:
  host: localhost

How to use

Instead of handling the routing by yourself, the bundle offers a high level and simple to use topic/message handler. Check this example to see it in action

import inject
from mqtt_bundle import MqttTopicManager, MqttConnectEvent
from applauncher.kernel import Event

class MyEvent(Event):
    event_name = "my_event"
    topic = "my_topic"

    def __init__(self, payload):
        self.payload = payload

class MyBundle(object):
    def __init__(self):
        self.event_listeners = [
            (MqttConnectEvent, self.mqtt_ready),
        ]


    def mqtt_ready(self, event):
        print("MQTT READY")
        mtm = inject.instance(MqttTopicManager)  # type: MqttTopicManager
        mtm.subscribe(MyEvent, lambda m: print(m))
        # d = mtm.publish(MyEvent("My Message!"))

The usage is simple, just inject MqttTopicManager and subscribe to an event providing the consumer function. The consumer function will receive the message payload.

To send a message just send and Event providing the payload. The payload can be anything serialized to str or bytes.

Going deeper

You can also manage the mqtt connection using directly the paho client.

import paho.mqtt.client as mqtt
import inject

client = inject.instance(mqtt.Client)
# Subscribe to a topic
client.subscribe("my_topic")

# Sending a message
client.publish("my_topic", "my_payload")

And for receive messages, just listen for MqttMessageEvent

So an example of a bundle using that would be:

from mqtt_bundle import MqttMessageEvent, MqttConnectEvent
import paho.mqtt.client as mqtt
import inject

class MyBundle(object):

    def __init__(self):

        self.event_listeners = [
            (MqttMessageEvent, self.new_message),
            (MqttConnectEvent, self.on_connect),
        ]
        
    @inject.params(client=mqtt.Client)
    def on_connect(self, event, client):
        client.subscribe("my_topic")
        client.publish("status_topic", "IM IN")
        
    def new_message(self, event, client):
        message = event.message
        # message variable is a paho message object
        print(f"New message received in topic {message.topic}: {message.payload}")

The cilent object is a paho-mqtt client so you can find more information and details at their documentation https://pypi.python.org/pypi/paho-mqtt