Python3: MQTT クライアントのサンプル

こちらで定めた仕様を満たすクライアントです。
IOT: MQTT クライアントのサンプル

Raspberry Pi で確認しました。

GPIO16 に接続した LED を ON/OFF します。

環境設定
ユーザーを gpio グループに所属させます。

sudo gpasswd -a uchida gpio

ライブラリーのインストール

sudo apt install python3-rpi.gpio

プログラム

subscribe_paho.py

#! /usr/bin/python3
#
#   subscribe_paho.py
#
#                   Oct/05/2021
# ------------------------------------------------------------------
import paho.mqtt.client as mqtt
import ssl
import sys
import json
import RPi.GPIO as GPIO

broker = "example.com"
topic = "example/test01"

# ------------------------------------------------------------------
def report_proc(on_off):
    rvalue = {}
    rvalue["state"] = {}
    rvalue["state"]["reported"] = {}
    rvalue["state"]["reported"]["led"] = on_off
    str_json = json.dumps(rvalue)
    client.publish(topic, str_json)
# ------------------------------------------------------------------
def led_proc(on_off):
    sys.stderr.write("led_proc " + on_off + "\n")
    if on_off == "on":
        GPIO.output(16,1)
    elif on_off == "off":
        GPIO.output(16,0)
    report_proc(on_off)
# ------------------------------------------------------------------
def on_connect(client, userdata, flags, respons_code):
    print('status {0}'.format(respons_code))
    client.subscribe(topic)

# ------------------------------------------------------------------
def on_message(client, userdata, msg):
    print(msg.topic + ' ' + str(msg.payload))
    bb = msg.payload
    str_json = bb.decode()
    print(str_json)
    try:
        dict_aa = json.loads(str_json)
        state = dict_aa['state']
        if 'desired' in state:
            desired = state['desired']
            on_off = desired['led']
            print(on_off)
            led_proc(on_off)
    except Exception as ee:
        sys.stderr.write("*** error *** in json.loads ***\n")
        sys.stderr.write(str(ee) + "\n")
    print()

# ------------------------------------------------------------------
sys.stderr.write("*** subscribe_paho *** start ***\n")
GPIO.setmode (GPIO.BCM)
GPIO.setup (16,GPIO.OUT)

client = mqtt.Client(client_id= "python",protocol=mqtt.MQTTv311)

client.on_connect = on_connect
client.on_message = on_message

#client.connect(broker, port=port, keepalive=6)
client.connect(broker, keepalive=6)
client.loop_forever()
#
sys.stderr.write("*** subscribe_paho *** end ***\n")
# ------------------------------------------------------------------