Hello Andrei.

The example from microsoft is for .NET Core.

The way I normal do this HttpClient in terms of Umbraco and .Net 4.x. I start by creating a Service of Depency injectable Class. Where HttpClient is Static, without dispose it. It means i share the connectionPool the HttpClient start.

public class TestService : ITestService {
     private static HttpClient _httpClient;

     public TestService() {
          if (_httpClient == null) {
               _httpClient = new HttpClient() { 
                   BaseAddress = new Uri("https://google.com") 
               }
          }
     }

     public bool CallGoogle() {
         return _httpClient.GetAsync("")
             .GetAwaiter()
             .GetResult()
             .IsSuccessStatusCode;
     }
}

From my RenderMvcController it will be like this:

 public class FrontpageController : RenderMvcController {
      private readonly ITestService _testService;

      public FrontpageController(ITestService testService) {
           _testService = testService;
      }

      public override ActionResult Index(ContentModel contentModel) {
           _testService.CallGoogle();

           return CurrentTemplate(contentModel);
      }
 }

At last but not least, i register the component to Umbraco DI, with a lifetime deffindt to be a singleton Lifetime.Singleton - one unique instance for the whole web application: The single instance will be shared across all web requests.

public class IocComposer : IUserComposer {
     public void Compose(Composition composition) {
          composition.Register<ITestService, TestService(liftetime: Lifetime.Singleton);
     }
}

Hops this will help you :)

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