Demo Python program illustrating connecting to AWS IoT Core and establishing multiple subscriptions in a single Subscription request

aws-iot-paho-client-multi-subscription-single-subscription-request.py

from __future__ import print_function
import sys
import ssl
import time
import datetime
import logging, traceback
import paho.mqtt.client as mqtt

IoT_protocol_name = "x-amzn-mqtt-ca"
aws_iot_endpoint = "a1tq0bx5we8tnk-ats.iot.us-east-1.amazonaws.com"
url = "https://{}".format(aws_iot_endpoint)

ca = "root-CA.crt"
cert = "daves_macbook.cert.pem"
private = "daves_macbook.private.key"

logger = logging.getLogger()
logger.setLevel(logging.DEBUG)
handler = logging.StreamHandler(sys.stdout)
log_format = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
handler.setFormatter(log_format)
logger.addHandler(handler)

def on_message(client, userdata, message):
    logger.info("Received message '" + str(message.payload) + "' on topic '" + message.topic + "' with QoS " + str(message.qos))

def ssl_alpn():
    try:
        #debug print opnessl version
        logger.info("open ssl version:{}".format(ssl.OPENSSL_VERSION))
        ssl_context = ssl.create_default_context()
        ssl_context.set_alpn_protocols([IoT_protocol_name])
        ssl_context.load_verify_locations(cafile=ca)
        ssl_context.load_cert_chain(certfile=cert, keyfile=private)

        return  ssl_context
    except Exception as e:
        print("exception ssl_alpn()")
        raise e

if __name__ == '__main__':

    try:
        mqttc = mqtt.Client()
        mqttc.on_message = on_message
        ssl_context= ssl_alpn()
        mqttc.tls_set_context(context=ssl_context)
        logger.info("start connect")
        mqttc.connect(aws_iot_endpoint, port=8883)
        logger.info("connect success")
        mqttc.loop_start()

        (result, message_id) = mqttc.subscribe([("sdk/test/Python0", 1), ("sdk/test/Python1", 1), ("sdk/test/Python2", 1)])
        logger.info("subscribe result: {}".format(result))
        logger.info("subscription request success? {}".format(mqtt.MQTT_ERR_SUCCESS == result))
        logger.info("subscribe message_id: {}".format(message_id))

        while True:
            now = datetime.datetime.now().strftime('%Y-%m-%dT%H:%M:%S')

            for x in range(3):
                topic = "{}{}".format("sdk/test/Python", x)
                logger.info("publishing {} on {}".format(now, topic))
                mqttc.publish(topic, now)

            time.sleep(1)

    except Exception as e:
        logger.error("exception main()")
        logger.error("e obj:{}".format(vars(e)))
        logger.error("message:{}".format(e.message))
        traceback.print_exc(file=sys.stdout)