CODEWITHSUNDEEP
c#asp.netweb-servicesazuremachine-learning
Remixed123
Remixed123

Reputation: 1585

Not Processing Azure ASP.NET REST Web Service Call

I am experimenting with the new Azure Machine Learning Service and have created a web service from my model. The service is working fine, as when I use a HTTPS tool to POST to it, I get the results I would expect.

My issue is with getting my ASP.NET code to work with it. I am using the code provided via the Machine Learning Web Services details page. I know it POSTs everything correctly, and the web service returns the correct JSON as I am packet tracing the communication. But for some reason my code does not acknowledge this return.

I have run this code from both an Azure Website an a local site within Visual Studio

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; }
    }
}

Upvotes: 1

Views: 1030

Answers (1)

Remixed123
Remixed123

Reputation: 1585

This issue is due to a bug which is discussed here - HttpClient.GetAsync(...) never returns when using await/async

Basically you need to add the ConfigureAwait(false) method.

So the line of code now looks like 

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

Upvotes: 1

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