asyncio-paho 0.6.0

A Paho MQTT client supporting asyncio loop without additional setup.

Asynchronous I/O (asyncio) Paho MQTT client

A Paho MQTT client supporting asyncio loop without additional setup. Forget about configuring the Paho network-loop. The client can almost be used as a drop-in replacement for Paho Client. The asyncio loop is automatically configured when you connect.

Features

• Drop-in replacement of Paho Client (inherits from Paho Client)
• Automatic configuration of asyncio loop.
• Reconnect on connection loss.
• Type hinted.
• Async callbacks.
• Non blocking connect (await client.asyncio_connect()).
• Python Asynchronous Context Manager handles cleanup.
• No threading, only asyncio.

Installation

pip install asyncio-paho

Usage

You should use Paho connect_async() or extension asyncio_connect() when connecting to avoid blocking. It is often usefull to configure subscriptions in on_connect callback to make sure all subscriptions is also setup on reconnect after connection loss.

Drop-in replacement

Remove all you calls to Paho looping like loop_forever() etc.

client = AsyncioPahoClient()
client.connect_async("mqtt.eclipseprojects.io")

# remove your current looping (loop_forever() etc)
# do mqtt stuff

client.Disconnect()

Asynchronous Context Manager

The client is an Asynchronous Context Manager and can be used with the Python with statement to atomatically disconnect and clean up.

async with AsyncioPahoClient() as client:
    client.connect_async("mqtt.eclipseprojects.io")

    # do mqtt stuff - client.Disconnect() is called when exiting context.

Extensions

The client has some additional async features (functions prefixed with asyncio_).

asyncio_connect

The classic Paho connect() is blocking. Paho connect_async() is not blocking, but returns before the connect is complete. Use asyncio_connect() to wait for connect to complete without blocking. This function also throws exception on connect failure. Please note that asyncio_connect() cannot be used together with on_connect /on_connect_fail (use asyncio_add_on_connect_listener and asyncio_add_on_connect_fail_listener instead of on_connect and on_connect_fail).

async with AsyncioPahoClient() as client:
    await client.asyncio_connect("mqtt.eclipseprojects.io")

asyncio_subscribe

The classic Paho connect() returns before the subscriptions is acknowledged by the broker, and on_subscribe / asyncio_listeners.add_on_subscribe() has to be uses to capture the acknowledge if needed. The async extension asyncio_subscribe() can be used to subscribe and wait for the acknowledge without blocking. It is often usefull to configure subscriptions when connecting to make sure subscriptions are reconfigured on reconnect (connection lost).

async def on_connect_async(client, userdata, flags_dict, result):
    await client.asyncio_subscribe("mytopic")

async def on_message_async(client, userdata, msg):
    print(f"Received from {msg.topic}: {str(msg.payload)}")

async with AsyncioPahoClient() as client:
    client.asyncio_listeners.add_on_connect(on_connect_async)
    client.asyncio_listeners.add_on_message(on_message_async)
    await client.asyncio_connect("mqtt.eclipseprojects.io")

Callbacks

Paho has a lot of callbacks. Async alternatives have been added for some of them, but they are mutally exclusive (you have to pick sync or async for eatch callback type). Multiple async listeners can be added to the same event, and a function handle to unsubscribe is returned when adding.

Classic Paho	Extension alternative	Called when
on_connect	asyncio_listeners.add_on_connect()	the broker responds to our connection
on_connect_fail	asyncio_listeners.add_on_connect_fail()	the client failed to connect to the broker
on_message	asyncio_listeners.add_on_message()	a message has been received on a topic that the client subscribes to
message_callback_add	asyncio_listeners.message_callback_add()	a message has been received on a topic for specific subscription filters
on_subscribe	asyncio_listeners.add_on_subscribe()	the broker responds to a subscribe request
on_publish	asyncio_listeners.add_on_publish()	a message that was to be sent using the publish() call has completed transmission to the broker

async def on_connect_async(client, userdata, message) -> None:
    client.subscribe("mytopic")

async with AsyncioPahoClient() as client:
    client.asyncio_add_on_connect_listener(on_connect_async)
    await client.asyncio_connect("mqtt.eclipseprojects.io")

asyncio_listeners.add_on_connect()

Add async on_connect event listener.

MQTT v3 callback signature:

async def callback(client: AsyncioPahoClient, userdata: Any, flags: dict[str, Any], rc: int)

MQTT v5 callback signature:

async def callback(client: AsyncioPahoClient, userdata: Any, flags: dict[str, reasonCode: ReasonCodes, properties: Properties])

asyncio_listeners.add_on_message()

Add async on_connect event listener. Callback signature:

async def callback(client: AsyncioPahoClient, userdata: Any, msg: MQTTMessage)

Dependencies

• Python 3.8 or later.
• Paho MQTT

The client uses asyncio event loop add_reader() and add_writer() methods. These methods are not supported on Windows by ProactorEventLoop (default on Windows from Python 3.8). You should be able to use another event loop like SelectorEventLoop.