MqttDemo1

1. install paho-mqtt.

```

import paho.mqtt.client as paho
import json
import  pandas as pd
import pytz
import time


client1= paho.Client('client1')
client1.connect('host:port')


def on_connect(client1, userdata, flags, rc):
    print("Connected with result code " + str(rc))
    client1.subscribe(const.presence_subscriber)

dis = {}
est = pytz.timezone('US/Eastern')

df = pd.DataFrame(columns=["uuid","timestamp","presenceDetected"])
print(df)


def on_message(client1, userdata, msg):
    payload = msg.payload.decode()
    print("Presence data received",payload)

    jsonPayload = json.loads(payload)

    df.loc[len(df)] = jsonPayload
    uuid = jsonPayload["uuid"]
    room = mt.Thisdict[uuid]

    timestamp= jsonPayload["timestamp"]
    ts = time.strptime(timestamp[:19], "%Y-%m-%dT%H:%M:%S")
    ts1 = time.strftime("%Y-%m-%d %H:%M:%S",ts)


    presenceDetected = jsonPayload["presenceDetected"]

    strPayload = str(room)+','+str(ts1)+','+str(presenceDetected)+"\n"

    with open(const.presence_mqtt_input,'a') as f:
       f.write(strPayload)



client1.on_connect = on_connect
client1.on_message = on_message

client1.loop_forever()
client1.disconnect();

```

the above code will constantly get the message from a topic and write to the file.