我正在尝试使用新的 Azure 机器学习服务，并从我的模型中创建了一个 Web 服务。该服务运行正常，当我使用 HTTPS 工具向其发送 POST 请求时，我得到了预期的结果。

我的问题在于如何让我的 ASP.NET 代码与之配合。我使用了机器学习 Web 服务详细信息页面提供的代码。我知道它正确地发送了所有 POST 请求，并且 Web 服务返回了正确的 JSON，因为我在跟踪通信数据包。但不知为何，我的代码无法识别这个返回值。

我已经在 Azure 网站和 Visual Studio 中的本地站点上运行了这段代码

namespace website{    public partial class ML : Page    {        protected void Page_Load(object sender, EventArgs e)        {            InvokeRequestResponseService().Wait();            //await InvokeRequestResponseService();        }        static async Task InvokeRequestResponseService()        {            using (var client = new HttpClient())            {                ScoreData scoreData = new ScoreData()                {                    FeatureVector = new Dictionary<string, string>()                     {                        { "age", "0" },                        { "education", "0" },                        { "education-num", "0" },                        { "marital-status", "0" },                        { "relationship", "0" },                        { "race", "0" },                        { "sex", "0" },                        { "capital-gain", "0" },                        { "capital-loss", "0" },                        { "hours-per-week", "0" },                        { "native-country", "0" },                    },                    GlobalParameters =                        new Dictionary<string, string>()                        {                        }                };                ScoreRequest scoreRequest = new ScoreRequest()                {                    Id = "score00001",                    Instance = scoreData                };                const string apiKey = "dg/pwCd7zMPc57lfOSJqxP8nbtKGV7//XXXXXXXXXXXXXXXXXXXXXXXXXXXXgvdVl/7VWjqe/ixOA=="; // Replace this with the API key for the web service                client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", apiKey);                client.BaseAddress = new Uri("https://ussouthcentral.services.XXXXXXX.net/workspaces/a932e11XXXXXXXXXXX29a69170eae9ed4/services/e8796c4382fb4XXXXXXXXXXXddac357/score");  // GETS STUCK ON THE NEXT LINE                HttpResponseMessage response = await client.PostAsJsonAsync("", scoreRequest); <---- NEVER RETURNS FROM THIS CALL                if (response.IsSuccessStatusCode)                {                    string result = await response.Content.ReadAsStringAsync();                    Console.WriteLine("Result: {0}", result);                }                else                {                    Console.WriteLine("Failed with status code: {0}", response.StatusCode);                }            }        }    }    public class ScoreData    {        public Dictionary<string, string> FeatureVector { get; set; }        public Dictionary<string, string> GlobalParameters { get; set; }    }    public class ScoreRequest    {        public string Id { get; set; }        public ScoreData Instance { get; set; }    }}

回答：

这个问题是由于一个在这里讨论的错误引起的 – HttpClient.GetAsync(…) 在使用 await/async 时永远不会返回

基本上，你需要添加 ConfigureAwait(false) 方法。

所以现在这行代码看起来像这样

HttpResponseMessage response = await client.PostAsJsonAsync("", scoreRequest).ConfigureAwait(false);