将Web Api服务自托管到Windows窗体中

Question

I am trying to self host a Web Api service inside a windows forms application using the code below

namespace MascoteAquarium.Desktop
{
    static class Program
    {
        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main()
        {
            var config = new HttpSelfHostConfiguration("http://localhost:8080");
            config.Routes.MapHttpRoute(
                "DefaultApi", "api/{controller}/id", new { id = RouteParameter.Optional });

            using (HttpSelfHostServer server = new HttpSelfHostServer(config))
            {
                server.OpenAsync().Wait();
            }

            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new frmMainMenu());
        }
    }
}

When I try

http://localhost:8080/api/*(some-controller)* 

I receive a NullReferenceException at System.Web.Http.SelfHost.HttpSelfHostServer.ProcessRequestContext(ChannelContext channelContext, RequestContext requestContext)

Someone know what is happening? Is it possible to self host inside a Win Forms app?

Answer 1

The problem is that the HttpSelfHostServer object gets lost just before Application.Run(...) , which contains the main event loop that keeps your program running. The using statement makes sure that Dispose method gets called for the object, in this case server , thus making it unavailable for answering requests, resulting in the NullReferenceException you are experiencing.

To fix the exception, your code should look like this:

...
using (HttpSelfHostServer server = new HttpSelfHostServer(config))
{
    server.OpenAsync().Wait();
    Application.EnableVisualStyles();
    Application.SetCompatibleTextRenderingDefault(false);
    Application.Run(new frmMainMenu());
}
...

Answer 2

1. You need to run the WinForms application (or VS if you run the WinForm app from the debugger) with elevated privileges (as Admin), otherwise the self-host will not be allowed to open a port.

2. Make sure no other application is running on port 8080 already