Azure 物联网中心框架 3.5

Question

是否有任何好的教程或指南可以通过框架 3.5 的设备通过 MQTT 协议(protocol)来使用 Azure IoT 中心？我找到了 M2MQTT 客户端，但它无法与 Azure IoT 中心配合使用。

Answer 1

IoT 中心使设备能够直接使用 MQTT v3.1.1 协议(protocol)与 IoT 中心设备端点进行通信。你可以看看这个document 。在文档中，教程是用 python 编写的，以下代码是使用 uPLibrary.Networking.M2Mqtt 的 C# 完整示例。

C# 示例:

    private static string hostName = "<iothub-hosename>";
    private static int port = 8883;
    private static string deviceId = "<deviceid>";
    private static string userName = "";
    private static string password = "";
    private static string certBase64 = "<DigiCert Baltimore Root Certificate>";

    static void Main(string[] args)
    {

        try
        {
            userName = $"{hostName}/{deviceId}/api-version=2016-11-14";
            password = $"SharedAccessSignature sr=<SAS Token>";

            byte[] certBytes = Convert.FromBase64String(certBase64);
            X509Certificate caCert = new X509Certificate(certBytes);

            MqttClient client = new MqttClient(hostName, port, true, caCert, null , MqttSslProtocols.TLSv1_0);
            client.ProtocolVersion = MqttProtocolVersion.Version_3_1_1;

            client.MqttMsgPublishReceived += Client_MqttMsgPublishReceived;
            client.MqttMsgPublished += Client_MqttMsgPublished;
            client.ConnectionClosed += Client_ConnectionClosed;
            client.Connect(deviceId, userName, password);
            if(client.IsConnected)
            {
                //To receive messages from IoT Hub, a device should subscribe using devices/{device_id}/messages/devicebound/# as a Topic Filter. 
                client.Subscribe(new string[] { $"devices/{deviceId}/messages/devicebound/#" }, new byte[] { MqttMsgBase.QOS_LEVEL_AT_LEAST_ONCE });

                //After making a successful connection, a device can send messages to IoT Hub using devices/{device_id}/messages/events/ or devices/{device_id}/messages/events/{property_bag} as a Topic Name. 
                client.Publish($"devices/{deviceid}/messages/events/", System.Text.Encoding.ASCII.GetBytes("{id=123}"), MqttMsgBase.QOS_LEVEL_AT_LEAST_ONCE, false);
            }
        }
        catch(Exception ex)
        {
            Console.Write(ex.Message);
        }

        Console.Read();
    }

    private static void Client_MqttMsgPublished(object sender, MqttMsgPublishedEventArgs e)
    {
        Console.WriteLine("Mqtt Published Message-[MsgId:{0}]:{1}", e.MessageId, e.IsPublished ? "Success": "Failure");
    }

    private static void Client_ConnectionClosed(object sender, EventArgs e)
    {
        Console.WriteLine("ConnectionClosed");
    }

    private static void Client_MqttMsgPublishReceived(object sender, MqttMsgPublishEventArgs e)
    {
        Console.WriteLine(System.Text.Encoding.ASCII.GetString(e.Message));
    }

在代码中，您可能需要将 DigiCert 巴尔的摩根证书从 certs.c 复制到 certBase64作为 base64 字符串(删除行 -----BEGIN CERTIFICATE----- 和 -----END CERTIFICATE-----，并删除 \r\n\)。

更新:

如何获取 SAS token ？

您可以使用Device Explorer要生成 SAS token ，请参阅 Using IoT Hub security tokens 的设备部分.