Following these steps should create a new ASP.NET Core MVC project in Visual Studio 2019. In the new project, create a new API controller and save it using the default name, i.e., ValuesController. We’ll use this project in the sections that follow.

HttpClient challenges

Although the HttpClient class doesn’t implement the IDisposable interface directly, it extends the System.Net.Http.HttpMessageInvoker class, which does implement IDisposable. Nevertheless, when working with HttpClient instances, you shouldn’t be disposing of them. Although you can call the Dispose method on an HttpClient instance, it is not a recommended practice.

What should you do instead? One option is to make the HttpClient instance static or wrap a non-static instance of the HttpClient inside a custom class and make it a singleton class. But a better alternative is to use IHttpClientFactory to retrieve an instance of HttpClient and then use the instance for calling action methods.

IHttpClientFactory and HttpClientFactory

IHttpClientFactory is an interface that is implemented by the DefaultHttpClientFactory class, which is an opinionated factory. The DefaultHttpClientFactory implements the IHttpClientFactory and IHttpMessageHandlerFactory interfaces. IHttpClientFactory was introduced to provide ASP.NET Core with excellent built-in support for creating, caching, and disposing of HttpClient instances.

Note that HttpClientFactory (discussed in my earlier article ) is just a helper to create HttpClient instances configured with the handlers provided. This class has the following methods:

Create(DelegatingHandler[]) Create(HttpMessageHandler, DelegatingHandler[]) CreatePipeline(HttpMessageHandler, IEnumerable )

The overloaded Create methods of the HttpClientFactory class look like this:

public static HttpClient Create(params DelegatingHandler[] handlers)
return Create(new HttpClientHandler(), handlers);
Source: https://github.com/aspnet/HttpClientFactory/blob/master/src/Microsoft.Extensions.Http/IHttpClientFactory.cs