Python SDK使用说明

SDK supports:

• 未加密和加密（TLS v1.2）的网络连接
• QoS 0 和 1
• 自动重连
• 所有设备的MQTT接口
• 所有网关的MQTT接口

当前的SDK基于paho-mqtt库

安装

使用pip安装：

pip3 install wt_mqtt

快速开始

初始化客户端并发布遥测数据

from wt_mqtt.wt_device_mqtt import WTDeviceMqttClient, WTPublishInfo


telemetry = {"temperature": 41.9, "enabled": False, "currentFirmwareVersion": "v1.2.2"}
client = WTDeviceMqttClient(host="things.xiaobodata.com", token="A1_TEST_TOKEN")
# Connect to WaveletThings
client.connect()
# Sending telemetry without checking the delivery status
client.send_telemetry(telemetry)
# Sending telemetry and checking the delivery status (QoS = 1 by default)
result = client.send_telemetry(telemetry)
# get is a blocking call that awaits delivery status
success = result.get() == WTPublishInfo.WT_ERR_SUCCESS
# Disconnect from WaveletThings
client.disconnect()

Connection using TLS

要通过SSL上的MQTT连接到WaveletThings，首先，您应该生成一个证书，并使用如下代码：

from wt_mqtt.wt_device_mqtt import WTDeviceMqttClient

client = WTDeviceMqttClient(host="things.xiaobodata.com", port=8883)
client.connect(tls=True,
               ca_certs="mqttserver.pub.pem",
               cert_file="mqttclient.nopass.pem")
client.disconnect()

使用设备API

WTDeviceMQTClient提供对Things平台的设备MQTT API的访问。 它允许发布遥测和属性更新、订阅属性更改、发送和接收RPC命令等。

订阅共享属性更新

如果需要接收共享属性更新，可以使用以下代码：

from time import sleep
from wt_mqtt.wt_device_mqtt import WTDeviceMqttClient


def callback(client, content, *args):
    print(content)


client = WTDeviceMqttClient("things.xiaobodata.com", "A1_TEST_TOKEN")
client.connect()
client.subscribe_to_attribute("uploadFrequency", callback)
client.subscribe_to_all_attributes(callback)
while True:
    sleep(1)

发布遥测数据

为了向Things发送数据，可以使用如下代码：

from time import time
from wt_mqtt.wt_device_mqtt import WTDeviceMqttClient, WTPublishInfo

telemetry_with_ts = {"ts": int(round(time() * 1000)), "values": {"temperature": 42.1, "humidity": 70}}
client = WTDeviceMqttClient("things.xiaobodata.com", "A1_TEST_TOKEN")
# we set maximum amount of messages sent to send them at the same time. it may stress memory but increases performance
client.max_inflight_messages_set(100)
client.connect()
results = []
result = True
for i in range(0, 100):
    results.append(client.send_telemetry(telemetry_with_ts))
for tmp_result in results:
    result &= tmp_result.get() == WTPublishInfo.WT_ERR_SUCCESS
print("Result", str(result))
client.disconnect()

请求属性

为了从Things请求属性值，可以使用以下示例，这个示例获取了"configuration", "targetFirmwareVersion"的值：

from time import sleep
from wt_mqtt.wt_device_mqtt import WTDeviceMqttClient


def on_attributes_change(client, result, *args):
    print(result)


client = WTDeviceMqttClient("things.xiaobodata.com", "A1_TEST_TOKEN")
client.connect()
client.request_attributes(["configuration", "targetFirmwareVersion"], callback=on_attributes_change)

while True:
    sleep(1)

响应服务端的RPC回调

如果您想发送某个RPC请求的响应，可以使用下面代码中的逻辑。 下面的示例连接到Things本地实例并等待RPC请求。 当接收到RPC请求时，客户机将向Things发送响应，其中包含来自具有客户机的机器的数据。

import json
from time import sleep

from psutil import cpu_percent, virtual_memory
from wt_mqtt.wt_device_mqtt import WTDeviceMqttClient


# dependently of request method we send different data back
def on_server_side_rpc_request(client, request_id, request_body):
    print(request_id, request_body)
    if request_body["method"] == "getCPULoad":
        client.send_rpc_reply(request_id, json.dumps({"CPU percent": cpu_percent()}))
    elif request_body["method"] == "getMemoryUsage":
        client.send_rpc_reply(request_id, json.dumps({"Memory": virtual_memory().percent}))


client = WTDeviceMqttClient("things.xiaobodata.com", "A1_TEST_TOKEN")
client.set_server_side_rpc_request_handler(on_server_side_rpc_request)
client.connect()

while True:
    sleep(1)

使用网关API

WTGatewayMqttClient继承了WTDeviceMqttClient，因此可以作为常规设备访问其所有API。 此外，网关能够代表连接到它的多个设备。

发送遥测和属性

可以使用如下代码：

from time import time
from wt_mqtt.wt_gateway_mqtt import WTGatewayMqttClient

gateway = WTGatewayMqttClient("things.xiaobodata.com", "GATEWAY_TEST_TOKEN")
gateway.connect()
gateway.gw_connect_device("Test Device A1")

gateway.gw_send_telemetry("Test Device A1", {"ts": int(round(time() * 1000)), "values": {"temperature": 42.2}})
gateway.gw_send_attributes("Test Device A1", {"firmwareVersion": "2.3.1"})

gateway.gw_disconnect_device("Test Device A1")
gateway.disconnect()

从server获取共享属性

获取Test Device A1的共享属性，可以使用如下代码：

from time import sleep
from wt_mqtt.wt_gateway_mqtt import WTGatewayMqttClient


def callback(client, result, *args):
    print(result)


gateway = WTGatewayMqttClient("things.xiaobodata.com", "GATEWAY_TEST_TOKEN")
gateway.connect()
gateway.gw_request_shared_attributes("Test Device A1", ["temperature"], callback)

while True:
    sleep(1)

响应服务端的RPC回调

可以使用如下代码：

import json
from time import sleep

from psutil import cpu_percent, virtual_memory
from wt_mqtt.wt_gateway_mqtt import WTGatewayMqttClient


def rpc_request_response(client, request_id, request_body):
    # request body contains id, method and other parameters
    print(request_body)
    method = request_body["data"]["method"]
    device = request_body["device"]
    req_id = request_body["data"]["id"]
    # dependently of request method we send different data back
    if method == 'getCPULoad':
        client.send_rpc_reply(request_id, json.dumps({"CPU percent": cpu_percent()}))
    elif method == 'getMemoryLoad':
        client.send_rpc_reply(request_id, json.dumps({"Memory": virtual_memory().percent}))
    else:
        print('Unknown method: ' + method)


gateway = WTGatewayMqttClient("things.xiaobodata.com", "GATEWAY_TEST_TOKEN")
gateway.connect()
# now rpc_request_response will process rpc requests from servers
gateway.gw_set_server_side_rpc_request_handler(rpc_request_response)
# without device connection it is impossible to get any messages
gateway.gw_connect_device("Test Device A1")

while True:
    sleep(1)