我们如何将Android/iOS应用连接到Azure IoT Central并发送遥测数据？

Question

我们已经在Azure IOT Central上注册了我们的IOT设备，并且能够在IOT Central上可视化遥测数据。但是，当我们使用Azure在Android示例应用IOT central上生成的主键发送遥测时，我们无法可视化数据。

我错过什么了吗？我们如何将iOS和Android注册为IoT Central上的一个设备以可视化数据？

Answer 1

以下屏幕片段显示了使用REST Post请求向IoT Central App发送遥测数据的示例：

单击按钮：

    private async void FabOnClick(object sender, EventArgs eventArgs)
    {
        double tempValue = double.Parse(floatingTemperatureLabel.Text);
        var payload = new { Temperature = tempValue };

        using (var client = new HttpClient())
        {
            client.DefaultRequestHeaders.Add("Authorization", sasToken);
            await client.PostAsync(requestUri, new StringContent(JsonConvert.SerializeObject(payload), Encoding.UTF8, "application/json"));
        }

        View view = (View) sender;
        Snackbar.Make(view, $"Sent: {tempValue}", Snackbar.LengthLong).SetAction("Action", (Android.Views.View.IOnClickListener)null).Show();
    }

遥测数据发送至物联中心APP：

注意，上面示例的requestUri和sasToken是在我的单独工具上创建的，但它们可以根据IoTC应用程序的scopeId、deviceId和SAS令牌从自定义azure函数中获得。

更新：

对于运行时注册（包括分配给设备模板），可以使用具有以下有效负载的REST PUT请求：

{
  "registrationId":"yourDeviceId",
  "payload": {
     "__iot:interfaces": {
       "CapabilityModelId":"yourCapabilityModelId"
     }
   }
}

请注意,授权头（如sasToken）可以由以下操作生成：

string sasToken = SharedAccessSignatureBuilder.GetSASToken($"{scopeId}/registrations/{deviceId}", deviceKey, "registration");

注册过程的状态可以通过REST GET获得，其中DeviceRegistrationResult为您提供IoT Central应用程序的底层Azure IoT Hub的名称空间，例如assignedHub属性。

正如我上面提到的，所有这些REST API调用都可以由azure函数处理（实现），并且您的移动应用程序将根据您的IoTC应用程序的scopeId、deviceId、deviceTemplateId和sas-token在post响应中获得requestUrl和sasToken。

更新-2：

我正在添加azure函数（HttpTriggerGetConnectionInfo）的示例，以获取设备http协议到IoT Central应用程序的连接信息：

该函数要求将以下变量添加到应用程序设置中：

• AzureIOTC_ScopeID
• AzureIOTC_Sastoken

run.csx：

#r "Newtonsoft.Json"

using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Azure.WebJobs;
using Microsoft.Extensions.Logging;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;
using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Net.Http;
using System.Security.Cryptography;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;
using System.Web;

public static async Task<IActionResult> Run(HttpRequest req, ILogger log)
{
    log.LogInformation("C# HTTP trigger function processed a request.");

    int retryCounter = 10;
    int pollingTimeInSeconds = 3;

    string deviceId = req.Query["deviceid"];
    string cmid = req.Query["cmid"];

    if (!Regex.IsMatch(deviceId, @"^[a-z0-9\-]+$"))
        throw new Exception($"Invalid format: DeviceID must be alphanumeric, lowercase, and may contain hyphens");

    string iotcScopeId = System.Environment.GetEnvironmentVariable("AzureIoTC_scopeId"); 
    string iotcSasToken = System.Environment.GetEnvironmentVariable("AzureIoTC_sasToken"); 

    if(string.IsNullOrEmpty(iotcScopeId) || string.IsNullOrEmpty(iotcSasToken))
        throw new ArgumentNullException($"Missing the scopeId and/or sasToken of the IoT Central App");

    string deviceKey = SharedAccessSignatureBuilder.ComputeSignature(iotcSasToken, deviceId);

    string address = $"https://global.azure-devices-provisioning.net/{iotcScopeId}/registrations/{deviceId}/register?api-version=2019-03-31";
    string sas = SharedAccessSignatureBuilder.GetSASToken($"{iotcScopeId}/registrations/{deviceId}", deviceKey, "registration");

    using (HttpClient client = new HttpClient())
    {
        client.DefaultRequestHeaders.Add("Authorization", sas);
        client.DefaultRequestHeaders.Add("accept", "application/json");
        string jsontext = string.IsNullOrEmpty(cmid) ? null : $"{{ \"__iot:interfaces\": {{ \"CapabilityModelId\":\"{cmid}\"}} }}";
        var response = await client.PutAsync(address, new StringContent(JsonConvert.SerializeObject(new { registrationId = deviceId, payload = jsontext }), Encoding.UTF8, "application/json"));

        var atype = new { errorCode = "", message = "", operationId = "", status = "", registrationState = new JObject() };
        do
        {
            dynamic operationStatus = JsonConvert.DeserializeAnonymousType(await response.Content.ReadAsStringAsync(), atype);
            if (!string.IsNullOrEmpty(operationStatus.errorCode))
            {
                throw new Exception($"{operationStatus.errorCode} - {operationStatus.message}");
            }
            response.EnsureSuccessStatusCode();
            if (operationStatus.status == "assigning")
            {
               Task.Delay(TimeSpan.FromSeconds(pollingTimeInSeconds)).Wait();
               address = $"https://global.azure-devices-provisioning.net/{iotcScopeId}/registrations/{deviceId}/operations/{operationStatus.operationId}?api-version=2019-03-31";
               response = await client.GetAsync(address);
            }
            else if (operationStatus.status == "assigned")
            {
               string assignedHub = operationStatus.registrationState.assignedHub;
               string cstr = $"HostName={assignedHub};DeviceId={deviceId};SharedAccessKey={deviceKey}";
               string requestUri = $"https://{assignedHub}/devices/{deviceId}/messages/events?api-version=2020-03-01";
               string deviceSasToken = SharedAccessSignatureBuilder.GetSASToken($"{assignedHub}/{deviceId}", deviceKey);

               log.LogInformation($"IoTC DeviceConnectionString:\n\t{cstr}");
               return new OkObjectResult(JObject.FromObject(new { iotHub = assignedHub, requestUri = requestUri, sasToken = deviceSasToken, deviceConnectionString = cstr }));
            }
            else
            {
                throw new Exception($"{operationStatus.registrationState.status}: {operationStatus.registrationState.errorCode} - {operationStatus.registrationState.errorMessage}");
            }
        } while (--retryCounter > 0);

        throw new Exception("Registration device status retry timeout exprired, try again.");
    } 
}

public sealed class SharedAccessSignatureBuilder
{
    public static string GetHostNameNamespaceFromConnectionString(string connectionString)
    {
        return GetPartsFromConnectionString(connectionString)["HostName"].Split('.').FirstOrDefault();
    }
    public static string GetSASTokenFromConnectionString(string connectionString, uint hours = 24)
    {
        var parts = GetPartsFromConnectionString(connectionString);
        if (parts.ContainsKey("HostName") && parts.ContainsKey("SharedAccessKey"))
            return GetSASToken(parts["HostName"], parts["SharedAccessKey"], parts.Keys.Contains("SharedAccessKeyName") ? parts["SharedAccessKeyName"] : null, hours);
        else
            return string.Empty;
    }
    public static string GetSASToken(string resourceUri, string key, string keyName = null, uint hours = 24)
    {
        try
        {
            var expiry = GetExpiry(hours);
            string stringToSign = System.Web.HttpUtility.UrlEncode(resourceUri) + "\n" + expiry;
            var signature = SharedAccessSignatureBuilder.ComputeSignature(key, stringToSign);
            var sasToken = keyName == null ?
                String.Format(CultureInfo.InvariantCulture, "SharedAccessSignature sr={0}&sig={1}&se={2}", HttpUtility.UrlEncode(resourceUri), HttpUtility.UrlEncode(signature), expiry) :
                String.Format(CultureInfo.InvariantCulture, "SharedAccessSignature sr={0}&sig={1}&se={2}&skn={3}", HttpUtility.UrlEncode(resourceUri), HttpUtility.UrlEncode(signature), expiry, keyName);
            return sasToken;
        }
        catch
        {
            return string.Empty;
        }
    }

    #region Helpers
    public static string ComputeSignature(string key, string stringToSign)
    {
        using (HMACSHA256 hmac = new HMACSHA256(Convert.FromBase64String(key)))
        {
            return Convert.ToBase64String(hmac.ComputeHash(Encoding.UTF8.GetBytes(stringToSign)));
        }
    }

    public static Dictionary<string, string> GetPartsFromConnectionString(string connectionString)
    {
        return connectionString.Split(new[] { ';' }, StringSplitOptions.RemoveEmptyEntries).Select(s => s.Split(new[] { '=' }, 2)).ToDictionary(x => x[0].Trim(), x => x[1].Trim(), StringComparer.OrdinalIgnoreCase);
    }

    // default expiring = 24 hours
    private static string GetExpiry(uint hours = 24)
    {
        TimeSpan sinceEpoch = DateTime.UtcNow - new DateTime(1970, 1, 1);
        return Convert.ToString((ulong)sinceEpoch.TotalSeconds + 3600 * hours);
    }

    public static DateTime GetDateTimeUtcFromExpiry(ulong expiry)
    {
        return (new DateTime(1970, 1, 1)).AddSeconds(expiry);
    }
    public static bool IsValidExpiry(ulong expiry, ulong toleranceInSeconds = 0)
    {
        return GetDateTimeUtcFromExpiry(expiry) - TimeSpan.FromSeconds(toleranceInSeconds) > DateTime.UtcNow;
    }

    public static string CreateSHA256Key(string secret)
    {
        using (var provider = new SHA256CryptoServiceProvider())
        {
            byte[] keyArray = provider.ComputeHash(UTF8Encoding.UTF8.GetBytes(secret));
            provider.Clear();
            return Convert.ToBase64String(keyArray);
        }
    }

    public static string CreateRNGKey(int keySize = 32)
    {
        byte[] keyArray = new byte[keySize];
        using (var provider = new RNGCryptoServiceProvider())
        {
            provider.GetNonZeroBytes(keyArray);
        }
        return Convert.ToBase64String(keyArray);
    }
    #endregion
}

配置mydeviceid并分配给urn:rk2019IOTCPreview:tester_653:1设备模板的函数的用法：

GET: https://yourFncApp.azurewebsites.net/api/HttpTriggerGetConnectionInfo?code=****&deviceid=mydeviceid&cmid=urn:rk2019iotcpreview:Tester_653:1

下面的屏幕片段显示了我们可以从设备模板中获取CapabilityModelId(cmid)的位置。注意，错误的值将返回：500内部服务器错误响应代码。

移动应用程序中收到的响应将允许将遥测数据发送到IoT中央应用程序：

{
  "iotHub": "iotc-xxxxx.azure-devices.net",
  "requestUri": "https://iotc-xxxxx.azure-devices.net/devices/mydeviceid/messages/events?api-version=2020-03-01",
  "sasToken": "SharedAccessSignature sr=iotc-xxxxx.azure-devices.net%2fmydeviceid&sig=xxxxxxxx&se=1592414760",
  "deviceConnectionString": "HostName=iotc-xxxxx.azure-devices.net;DeviceId=mydeviceid;SharedAccessKey=xxxxxxx"
 }

响应对象可以缓存在移动应用程序中，并在其过期之前刷新。请注意，上述sasToken的有效期为24小时（默认值）。

下面的屏幕片段展示了从移动应用程序向Azure IoT Central应用程序发送遥测数据的概念：