MQTT client

About

Asynchronous MQTT client for 3.1.1 protocol version.

Installation

Recommended way (via pip):

$ pip install aio-mqtt

Example

Simple echo server:

import asyncio as aio
import logging
import typing as ty

import aio_mqtt

logger = logging.getLogger(__name__)


class EchoServer:

    def __init__(
            self,
            reconnection_interval: int = 10,
            loop: ty.Optional[aio.AbstractEventLoop] = None
    ) -> None:
        self._reconnection_interval = reconnection_interval
        self._loop = loop or aio.get_event_loop()
        self._client = aio_mqtt.Client(loop=self._loop)
        self._tasks = [
            self._loop.create_task(self._connect_forever()),
            self._loop.create_task(self._handle_messages())
        ]

    async def close(self) -> None:
        for task in self._tasks:
            if task.done():
                continue
            task.cancel()
            try:
                await task
            except aio.CancelledError:
                pass
        if self._client.is_connected():
            await self._client.disconnect()

    async def _handle_messages(self) -> None:
        async for message in self._client.delivered_messages('in'):
            while True:
                try:
                    await self._client.publish(
                        aio_mqtt.PublishableMessage(
                            topic_name='out',
                            payload=message.payload,
                            qos=aio_mqtt.QOSLevel.QOS_1
                        )
                    )
                except aio_mqtt.ConnectionClosedError as e:
                    logger.error("Connection closed", exc_info=e)
                    await self._client.wait_for_connect()
                    continue

                except Exception as e:
                    logger.error("Unhandled exception during echo message publishing", exc_info=e)

                break

    async def _connect_forever(self) -> None:
        while True:
            try:
                connect_result = await self._client.connect('localhost')
                logger.info("Connected")

                await self._client.subscribe(('in', aio_mqtt.QOSLevel.QOS_1))

                logger.info("Wait for network interruptions...")
                await connect_result.disconnect_reason
            except aio.CancelledError:
                raise

            except aio_mqtt.AccessRefusedError as e:
                logger.error("Access refused", exc_info=e)

            except aio_mqtt.ConnectionLostError as e:
                logger.error("Connection lost. Will retry in %d seconds", self._reconnection_interval, exc_info=e)
                await aio.sleep(self._reconnection_interval, loop=self._loop)

            except aio_mqtt.ConnectionCloseForcedError as e:
                logger.error("Connection close forced", exc_info=e)
                return

            except Exception as e:
                logger.error("Unhandled exception during connecting", exc_info=e)
                return

            else:
                logger.info("Disconnected")
                return


if __name__ == '__main__':
    logging.basicConfig(
        level='DEBUG'
    )
    loop = aio.new_event_loop()
    server = EchoServer(reconnection_interval=10, loop=loop)
    try:
        loop.run_forever()
    except KeyboardInterrupt:
        pass

    finally:
        loop.run_until_complete(server.close())
        loop.run_until_complete(loop.shutdown_asyncgens())
        loop.close()

License

Copyright 2019-2020 Not Just A Toy Corp.

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.