Get ASP.NET MVC5 WebAPI token fails sometimes

Question

Get ASP.NET MVC5 WebAPI token fails sometimes

Code

string GetAPITokenSync(string username, string password, string apiBaseUri)
              


        

Answer 1

It's hard to say for certain, but the way you're blocking HttpClient calls can't be helping. HttpClient is an async-only library; you may have a deadlock situation. I suggest getting rid of all .Results and .Wait()s and write everything asynchronously, using async/await. And your Task.Run is achieving nothing, so that should go.

I understand this is Topshelf app ported over from a console app. I'm not very familiar with Topshelf, but I assume that, like console apps, you need to block somewhere or your app will simply exit. The place to do that is at the very top - the entry point of the app.

This demonstrates the pattern, along with a re-write of your GetApiToken method:

// app entry point - the only place you should block
void Main()
{
    MainAsync().Wait();
}

// the "real" starting point of your app logic. do everything async from here on
async Task MainAsync()
{
    ...
    var token = await GetApiTokenAsync(username, password, apiBaseUri);
    ...
}

async Task GetApiTokenAsync(string username, string password, string apiBaseUri)
{
    var token = string.Empty;

    using (var client = new HttpClient())
    {
        client.BaseAddress = new Uri(apiBaseUri);
        client.DefaultRequestHeaders.Accept.Clear();
        client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
        client.Timeout = TimeSpan.FromSeconds(60);  

        //setup login data
        var formContent = new FormUrlEncodedContent(new[]
        {
         new KeyValuePair("grant_type", "password"),
         new KeyValuePair("username", username),
         new KeyValuePair("password", password),
         });

        //send request               
        HttpResponseMessage responseMessage = await client.PostAsync("/Token", formContent);
        var responseJson = await responseMessage.Content.ReadAsStringAsync();
        var jObject = JObject.Parse(responseJson);
        token = jObject.GetValue("access_token").ToString();

        return token;
    }
}