How to host Web API in a separate process

While IIS is a popular choice for hosting Web APIs, it's not the only option. You can host your Web API in a separate process using a host application, such as a console.

1. Create a Console Application to Host the API

To begin, we will create a console application to self-host our Web API.

• Create the Console Application: Open Visual Studio and create a new Console Application project. Name it something like "BookWebAPIHost."
• Install Required NuGet Package: Right-click on the project in Solution Explorer, select Manage NuGet Packages, search for Microsoft.AspNet.WebAPI.SelfHost, and install it. This package allows you to host your Web API without IIS.
• Write the Self-Hosting Code: In your Program.cs file, you can write code to host the API on a specific URL (e.g., http://localhost:8080):

using System;
using System.Net.Http;
using System.Web.Http;
using System.Web.Http.SelfHost;

class Program
{
    static void Main(string[] args)
    {
        string baseAddress = "http://localhost:8080";
        var config = new HttpSelfHostConfiguration(baseAddress);

        config.Routes.MapHttpRoute(
            "API Default", "api/{controller}/{id}",
            new { id = RouteParameter.Optional });

        using (HttpSelfHostServer server = new HttpSelfHostServer(config))
        {
            server.OpenAsync().Wait();
            Console.WriteLine("Service started ... Press Enter to quit.");
            Console.ReadLine();
        }
    }
}

2. Create the API Model

Now let’s create a model that represents the data structure we will work with.

namespace SimpleWebAPI.Models
{
    public class Book
    {
        public int Id { get; set; }
        public string Title { get; set; }
        public string Author { get; set; }
    }
}

3. Create the Web API Controller

Next, create a controller that will handle the API logic. This controller will use the Book model to return a list of books:

using System.Collections.Generic;
using System.Web.Http;
using SimpleWebAPI.Models;

public class BooksController : ApiController
{
    private static List<Book> books = new List<Book>
    {
        new Book { Id = 1, Title = "The Great Gatsby", Author = "F. Scott Fitzgerald" },
        new Book { Id = 2, Title = "1984", Author = "George Orwell" }
    };

    public IEnumerable<Book> GetAllBooks()
    {
        return books;
    }
}

4. Consume the Web API

To consume the API we just created, you can create another console application.

This application will send HTTP requests to our hosted Web API and display the results.

1. Create the New Console Application: In Visual Studio, create another console application project named "BookWebAPIClient."

2. Install NuGet Packages: Add the Microsoft.AspNet.WebAPI.Client package to the new project, as it will help with consuming the Web API.

3. Create the Code to Call the API: In your Program.cs, use the HttpClient class to request data from the Web API:

using System;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Threading.Tasks;
using System.Collections.Generic;

namespace BookWebAPIClient
{
    class Program
    {
        static async Task Main(string[] args)
        {
            HttpClient client = new HttpClient();
            client.BaseAddress = new Uri("http://localhost:8080/");
            client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

            HttpResponseMessage response = await client.GetAsync("api/books");

            if (response.IsSuccessStatusCode)
            {
                var books = await response.Content.ReadAsAsync<List<Book>>();
                foreach (var book in books)
                {
                    Console.WriteLine("{0}: {1} by {2}", book.Id, book.Title, book.Author);
                }
            }
            else
            {
                Console.WriteLine("Error: {0} ({1})", (int)response.StatusCode, response.ReasonPhrase);
            }

            Console.ReadKey();
        }
    }
}

5. Run the Application

• Start the Web API: First, run the BookWebAPIHost project, which will start the Web API on http://localhost:8080.

• Consume the Web API: Run the BookWebAPIClient project. This will make a request to the API, retrieve the list of books, and display them in the console.

By following these steps, you can easily self-host a Web API using a console application.