The :class:`~hbmqtt.client.MQTTClient` class implements the client part of MQTT protocol. It can be used to publish and/or subscribe MQTT message on a broker accessible on the network through TCP or websocket protocol, both secured or unsecured.
Usage examples
--------------
Subscriber
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The example below shows how to write a simple MQTT client which subscribes a topic and prints every messages received from the broker :
..code-block:: python
@asyncio.coroutine
def uptime_coro():
C = MQTTClient()
yield from C.connect('mqtt://test.mosquitto.org/')
The :class:`~hbmqtt.client.MQTTClient```__init__`` method accepts a ``config`` parameter which allow to setup some behaviour and defaults settings. This argument must be a Python dict object which may contain the following entries:
*``keep_alive``: keep alive (in seconds) to send when connecting to the broker (defaults to ``10`` seconds). :class:`~hbmqtt.client.MQTTClient` will *auto-ping* the broker if not message is sent within the keep-alive interval. This avoids disconnection from the broker.
*``ping_delay``: *auto-ping* delay before keep-alive times out (defaults to ``1`` seconds).
*``default_qos``: Default QoS used by :meth:`~hbmqtt.client.MQTTClient.publish` if ``qos`` argument is not given.
*``default_retain``: Default retain used by :meth:`~hbmqtt.client.MQTTClient.publish` if ``qos`` argument is not given.,
*``auto_reconnect``: enable or disable auto-reconnect feature (defaults to ``True``).
*``reconnect_max_interval``: maximum interval (in seconds) to wait before two connection retries (defaults to ``10``).
*``reconnect_retries``: maximum number of connect retries (defaults to ``2``).
Default QoS and default retain can also be overriden by adding a ``topics`` with may contain QoS and retain values for specific topics. See the following example:
..code-block:: python
config = {
'keep_alive': 10,
'ping_delay': 1,
'default_qos': 0,
'default_retain': False,
'auto_reconnect': True,
'reconnect_max_interval': 5,
'reconnect_retries': 10,
'topics': {
'/test': { 'qos': 1 },
'/some_topic': { 'qos': 2, 'retain': True }
}
}
With this setting any message published will set with QOS_0 and retain flag unset except for :
* messages sent to ``/test`` topic : they will be sent with QOS_1
* messages sent to ``/some_topic`` topic : they will be sent with QOS_2 and retain flag set
In any case, the ``qos`` and ``retain`` argument values passed to method :meth:`~hbmqtt.client.MQTTClient.publish` will override these settings.
