为什么我不能使用 Python（使用此代码）通过 MQTT 将图像发送到

Question

下面是我尝试使用 MQTT 将图像发送到 Google Cloud IoT Core。我已阅读以下对我有所帮助的帖子，但我的代码仍然无法正常工作：如何在 Python 中使用 Mosquitto 将文件发布到 AWS-IoT以及如何在 Python 中使用 Mosquitto 发布文件？.

我猜我的错误与qosin theclient.publish或我如何使用循环有关，但恐怕到目前为止我对这些因素的试验对我没有帮助（尝试qos= 0/1/2 和 eg client.loop_forever()）。我的图像是 1.2 Mb，所以据我所知，这应该不是问题。

#!/usr/bin/python

from picamera import PiCamera

import datetime

import time

import jwt

import paho.mqtt.client as mqtt

from time import sleep

# Define some project-based variables to be used below. This should be the only

# block of variables that you need to edit in order to run this script

ssl_private_key_filepath = 'FILE1.pem'

ssl_algorithm = 'RS256' # Either RS256 or ES256

root_cert_filepath = 'FILE2.PEM'

project_id = 'PROJECT_ID'

gcp_location = 'LOCATION'

registry_id = 'REG_ID'

device_id = 'DEVICE_ID'

# end of user-variables

run = True

cur_time = datetime.datetime.utcnow()

def create_jwt():

  token = {

      'iat': cur_time,

      'exp': cur_time + datetime.timedelta(minutes=60),

      'aud': project_id

  }

  with open(ssl_private_key_filepath, 'r') as f:

    private_key = f.read()

  return jwt.encode(token, private_key, ssl_algorithm)

_CLIENT_ID = 'projects/{}/locations/{}/registries/{}/devices/{}'.format(project_id, gcp_location, registry_id, device_id)

_MQTT_TOPIC = '/devices/{}/events'.format(device_id)

client = mqtt.Client(client_id=_CLIENT_ID)

# authorization is handled purely with JWT, no user/pass, so username can be whatever

client.username_pw_set(

    username='unused',

    password=create_jwt())

def error_str(rc):

    return '{}: {}'.format(rc, mqtt.error_string(rc))

def on_connect(unusued_client, unused_userdata, unused_flags, rc):

    print('on_connect', error_str(rc))

def on_publish(unused_client, unused_userdata, unused_mid):

    print('on_publish')

    run = False

client.on_connect = on_connect

client.on_publish = on_publish

client.tls_set(ca_certs=root_cert_filepath) # Replace this with 3rd party cert if that was used when creating registry

client.connect('mqtt.googleapis.com', 8883)

Answer 1

答案由@Aaron 提供。“1.2Mb 太大了……”遥测事件有效负载限制为 256 KB，不能增加