255 lines
10 KiB
Python
255 lines
10 KiB
Python
# Copyright (c) 2016 Roger Light <roger@atchoo.org>
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#
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# All rights reserved. This program and the accompanying materials
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# are made available under the terms of the Eclipse Public License v1.0
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# and Eclipse Distribution License v1.0 which accompany this distribution.
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#
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# The Eclipse Public License is available at
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# http://www.eclipse.org/legal/epl-v10.html
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# and the Eclipse Distribution License is available at
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# http://www.eclipse.org/org/documents/edl-v10.php.
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#
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# Contributors:
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# Roger Light - initial API and implementation
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"""
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This module provides some helper functions to allow straightforward subscribing
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to topics and retrieving messages. The two functions are simple(), which
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returns one or messages matching a set of topics, and callback() which allows
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you to pass a callback for processing of messages.
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"""
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import paho.mqtt.client as paho
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import paho.mqtt as mqtt
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def _on_connect(client, userdata, flags, rc):
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"""Internal callback"""
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if rc != 0:
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raise mqtt.MQTTException(paho.connack_string(rc))
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if isinstance(userdata['topics'], list):
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for topic in userdata['topics']:
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client.subscribe(topic, userdata['qos'])
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else:
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client.subscribe(userdata['topics'], userdata['qos'])
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def _on_message_callback(client, userdata, message):
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"""Internal callback"""
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userdata['callback'](client, userdata['userdata'], message)
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def _on_message_simple(client, userdata, message):
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"""Internal callback"""
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if userdata['msg_count'] == 0:
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return
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# Don't process stale retained messages if 'retained' was false
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if message.retain and not userdata['retained']:
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return
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userdata['msg_count'] = userdata['msg_count'] - 1
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if userdata['messages'] is None and userdata['msg_count'] == 0:
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userdata['messages'] = message
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client.disconnect()
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return
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userdata['messages'].append(message)
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if userdata['msg_count'] == 0:
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client.disconnect()
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def callback(callback, topics, qos=0, userdata=None, hostname="localhost",
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port=1883, client_id="", keepalive=60, will=None, auth=None,
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tls=None, protocol=paho.MQTTv311, transport="tcp",
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clean_session=True):
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"""Subscribe to a list of topics and process them in a callback function.
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This function creates an MQTT client, connects to a broker and subscribes
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to a list of topics. Incoming messages are processed by the user provided
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callback. This is a blocking function and will never return.
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callback : function of the form "on_message(client, userdata, message)" for
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processing the messages received.
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topics : either a string containing a single topic to subscribe to, or a
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list of topics to subscribe to.
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qos : the qos to use when subscribing. This is applied to all topics.
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userdata : passed to the callback
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hostname : a string containing the address of the broker to connect to.
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Defaults to localhost.
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port : the port to connect to the broker on. Defaults to 1883.
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client_id : the MQTT client id to use. If "" or None, the Paho library will
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generate a client id automatically.
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keepalive : the keepalive timeout value for the client. Defaults to 60
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seconds.
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will : a dict containing will parameters for the client: will = {'topic':
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"<topic>", 'payload':"<payload">, 'qos':<qos>, 'retain':<retain>}.
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Topic is required, all other parameters are optional and will
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default to None, 0 and False respectively.
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Defaults to None, which indicates no will should be used.
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auth : a dict containing authentication parameters for the client:
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auth = {'username':"<username>", 'password':"<password>"}
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Username is required, password is optional and will default to None
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if not provided.
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Defaults to None, which indicates no authentication is to be used.
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tls : a dict containing TLS configuration parameters for the client:
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dict = {'ca_certs':"<ca_certs>", 'certfile':"<certfile>",
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'keyfile':"<keyfile>", 'tls_version':"<tls_version>",
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'ciphers':"<ciphers">}
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ca_certs is required, all other parameters are optional and will
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default to None if not provided, which results in the client using
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the default behaviour - see the paho.mqtt.client documentation.
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Alternatively, tls input can be an SSLContext object, which will be
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processed using the tls_set_context method.
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Defaults to None, which indicates that TLS should not be used.
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transport : set to "tcp" to use the default setting of transport which is
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raw TCP. Set to "websockets" to use WebSockets as the transport.
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clean_session : a boolean that determines the client type. If True,
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the broker will remove all information about this client
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when it disconnects. If False, the client is a persistent
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client and subscription information and queued messages
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will be retained when the client disconnects.
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Defaults to True.
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"""
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if qos < 0 or qos > 2:
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raise ValueError('qos must be in the range 0-2')
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callback_userdata = {
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'callback':callback,
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'topics':topics,
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'qos':qos,
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'userdata':userdata}
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client = paho.Client(client_id=client_id, userdata=callback_userdata,
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protocol=protocol, transport=transport,
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clean_session=clean_session)
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client.on_message = _on_message_callback
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client.on_connect = _on_connect
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if auth:
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username = auth.get('username')
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if username:
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password = auth.get('password')
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client.username_pw_set(username, password)
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else:
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raise KeyError("The 'username' key was not found, this is "
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"required for auth")
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if will is not None:
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client.will_set(**will)
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if tls is not None:
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if isinstance(tls, dict):
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client.tls_set(**tls)
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else:
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# Assume input is SSLContext object
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client.tls_set_context(tls)
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client.connect(hostname, port, keepalive)
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client.loop_forever()
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def simple(topics, qos=0, msg_count=1, retained=True, hostname="localhost",
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port=1883, client_id="", keepalive=60, will=None, auth=None,
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tls=None, protocol=paho.MQTTv311, transport="tcp",
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clean_session=True):
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"""Subscribe to a list of topics and return msg_count messages.
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This function creates an MQTT client, connects to a broker and subscribes
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to a list of topics. Once "msg_count" messages have been received, it
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disconnects cleanly from the broker and returns the messages.
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topics : either a string containing a single topic to subscribe to, or a
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list of topics to subscribe to.
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qos : the qos to use when subscribing. This is applied to all topics.
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msg_count : the number of messages to retrieve from the broker.
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if msg_count == 1 then a single MQTTMessage will be returned.
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if msg_count > 1 then a list of MQTTMessages will be returned.
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retained : If set to True, retained messages will be processed the same as
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non-retained messages. If set to False, retained messages will
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be ignored. This means that with retained=False and msg_count=1,
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the function will return the first message received that does
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not have the retained flag set.
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hostname : a string containing the address of the broker to connect to.
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Defaults to localhost.
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port : the port to connect to the broker on. Defaults to 1883.
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client_id : the MQTT client id to use. If "" or None, the Paho library will
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generate a client id automatically.
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keepalive : the keepalive timeout value for the client. Defaults to 60
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seconds.
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will : a dict containing will parameters for the client: will = {'topic':
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"<topic>", 'payload':"<payload">, 'qos':<qos>, 'retain':<retain>}.
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Topic is required, all other parameters are optional and will
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default to None, 0 and False respectively.
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Defaults to None, which indicates no will should be used.
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auth : a dict containing authentication parameters for the client:
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auth = {'username':"<username>", 'password':"<password>"}
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Username is required, password is optional and will default to None
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if not provided.
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Defaults to None, which indicates no authentication is to be used.
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tls : a dict containing TLS configuration parameters for the client:
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dict = {'ca_certs':"<ca_certs>", 'certfile':"<certfile>",
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'keyfile':"<keyfile>", 'tls_version':"<tls_version>",
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'ciphers':"<ciphers">}
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ca_certs is required, all other parameters are optional and will
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default to None if not provided, which results in the client using
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the default behaviour - see the paho.mqtt.client documentation.
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Alternatively, tls input can be an SSLContext object, which will be
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processed using the tls_set_context method.
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Defaults to None, which indicates that TLS should not be used.
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transport : set to "tcp" to use the default setting of transport which is
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raw TCP. Set to "websockets" to use WebSockets as the transport.
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clean_session : a boolean that determines the client type. If True,
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the broker will remove all information about this client
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when it disconnects. If False, the client is a persistent
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client and subscription information and queued messages
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will be retained when the client disconnects.
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Defaults to True.
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"""
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if msg_count < 1:
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raise ValueError('msg_count must be > 0')
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# Set ourselves up to return a single message if msg_count == 1, or a list
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# if > 1.
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if msg_count == 1:
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messages = None
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else:
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messages = []
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userdata = {'retained':retained, 'msg_count':msg_count, 'messages':messages}
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callback(_on_message_simple, topics, qos, userdata, hostname, port,
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client_id, keepalive, will, auth, tls, protocol, transport,
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clean_session)
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return userdata['messages']
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