c# - Hosting ASP.NET Core API in a Windows Forms Application

Question

Background: I am working on a project that involves a WinForms app. The client wants to expose a local-only HTTP server to allow other apps to trigger functionality on a running instance of the WinForms app via a REST API (or similar). The preference is to implement the aforementioned API using ASP.NET Core.

My question is thus: How do I structure a project to have both an ASP.NET Core API and a WinForms GUI in the same process? Are there any pitfalls I'd have to be wary of?

Answer 1

Hosting ASP.NET CORE API in a Windows Forms Application and Interaction with Form

Here is a basic step by step example about how to create a project to host ASP.NET CORE API inside a Windows Forms Application and perform some interaction with Form.

To do so, follow these steps:

1. Create a Windows Forms Application name it MyWinFormsApp
2. Open Form1 in design mode and drop a TextBox on it.
3. Change the Modifiers property of the textBox1 in designer to Public and save it.
4. Install Microsoft.AspNetCore.Mvc package
5. Install Microsoft.AspNetCore package

6. Create a Startup.cs file in the root of the project, and copy the following code:

   using Microsoft.AspNetCore.Builder;
   using Microsoft.AspNetCore.Hosting;
   using Microsoft.AspNetCore.Mvc;
   using Microsoft.Extensions.Configuration;
   using Microsoft.Extensions.DependencyInjection;
   namespace MyWinFormsApp
   {
       public class Startup
       {
           public Startup(IConfiguration configuration)
           {
               Configuration = configuration;
           }
           public IConfiguration Configuration { get; }
           public void ConfigureServices(IServiceCollection services)
           {
               services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);
           }
           public void Configure(IApplicationBuilder app, IHostingEnvironment env)
           {
               if (env.IsDevelopment())
               {
                   app.UseDeveloperExceptionPage();
               }
               app.UseMvc();
           }
       }
   }
   

7. Copy the following code in Program.cs:

   using System;
   using System.Threading;
   using System.Windows.Forms;
   using Microsoft.AspNetCore;
   using Microsoft.AspNetCore.Hosting;
   
   namespace MyWinFormsApp
   {
       public class Program
       {
           public static Form1 MainForm { get; private set; }
   
           [STAThread]
           public static void Main(string[] args)
           {
               CreateWebHostBuilder(args).Build().RunAsync();
   
               Application.EnableVisualStyles();
               Application.SetCompatibleTextRenderingDefault(false);
               MainForm = new Form1();
               Application.Run(MainForm);
           }
   
           public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
               WebHost.CreateDefaultBuilder(args)
                   .UseStartup<Startup>();
       }
   }
   

8. Create a folder called Controllers in the root of the project.

9. Create ValuesController.cs in the Controllers folder and copy the following code to file:

   using System;
   using Microsoft.AspNetCore.Mvc;
   
   namespace MyWinFormsApp.Controllers
   {
       [Route("api/[controller]")]
       [ApiController]
       public class ValuesController : ControllerBase
       {
           [HttpGet]
           public ActionResult<string> Get()
           {
               string text = "";
               Program.MainForm.Invoke(new Action(() =>
               {
                   text = Program.MainForm.textBox1.Text;
               }));
               return text;
           }
   
           [HttpGet("{id}")]
           public ActionResult Get(string id)
           {
               Program.MainForm.Invoke(new Action(() =>
               {
                   Program.MainForm.textBox1.Text = id;
               }));
               return Ok();
           }
       }
   }
   

10. Run the application.

11. Type "hi" in the textBox1
12. Open browser and browse http://localhost:5000/api/values → You will see hi as response.
13. http://localhost:5000/api/values/bye → You will see bye in textBox1