How to use DependencyResolver in Net48 selfhosted application?

Question

I have gotten a task that contains creating a .Net 4.8 application that contains a "HttpSelfHostServer". I'm stuck in the quest of assigning "IServiceCollection services" to config.DependencyResolver (of type System.Web.Http.Dependencies.IDependencyResolver)

I would really like not to use autofac or other frameworks, but all guids I can find are pointing toward these frameworks. Isn't Microsoft providing a way through?

Answer 1

I just had to solve the same issue. This is how i did it:

First I created a new facade class to map the IServiceCollection from the host builder to the interface HttpSelfHostConfiguration supports:

using System;
using System.Collections.Generic;
using System.Web.Http.Dependencies;
using Microsoft.Extensions.DependencyInjection;

namespace IntegrationReceiver.WebApi
{
    public class HttpSelfHostDependencyResolver : IDependencyResolver
    {
        private readonly IServiceProvider sp;
        private readonly IServiceScope scope;

        public HttpSelfHostDependencyResolver(IServiceProvider sp)
        {
            this.sp = sp;
            this.scope = null;
        }

        public HttpSelfHostDependencyResolver(IServiceScope scope)
        {
            this.sp = scope.ServiceProvider;
            this.scope = scope;
        }

        public IDependencyScope BeginScope() => new HttpSelfHostDependencyResolver(sp.CreateScope());

        public void Dispose() => scope?.Dispose();

        public object GetService(Type serviceType) => sp.GetService(serviceType);

        public IEnumerable<object> GetServices(Type serviceType) => sp.GetServices(serviceType);
    }
}

This required me to get the latest NuGet package Microsoft.Extensions.DependencyInjection.Abstractions according to an answer here: How do I see all services that a .NET IServiceProvider can provide?

I then registered my HttpSelfHostServer in the service provider with this code:

services.AddSingleton(sp => new HttpSelfHostDependencyResolver(sp));

services.AddSingleton(sp =>
{
    //Starting the HttpSelfHostServer with user-level permissions requires to first run a command like
    // netsh http add urlacl url=http://+:8080/ user=[DOMAINNAME]\[USERNAME]
    var config = new HttpSelfHostConfiguration("http://localhost:8080");
    config.Routes.MapHttpRoute("API Default", "api/{controller}/{id}", new { id = RouteParameter.Optional });
    config.DependencyResolver = sp.GetRequiredService<HttpSelfHostDependencyResolver>();
    return new HttpSelfHostServer(config);
});

And finally, to find my ApiController, I had to register that too in the service provider. I did that simply with:

services.AddScoped<HealthCheckController>();

For brewity, I'm just including my api controller below to illustrate how it now gets its dependencies:

using System.Net.Http;
using System.Threading.Tasks;
using System.Web.Http;

namespace IntegrationReceiver.WebApi
{
    public class HealthCheckController : ApiController
    {
        private readonly ServiceBusRunner serviceBusRunner;

        public HealthCheckController(ServiceBusRunner serviceBusRunner)
        {
            this.serviceBusRunner = serviceBusRunner;
        }


        [HttpGet]
        public async Task<HttpResponseMessage> Get()
        {
            var response = new
            {
                serviceBusRunner.RunningTasks,
                serviceBusRunner.MaxRunningTasks
            };

            return await Json(response)
                .ExecuteAsync(System.Threading.CancellationToken.None);
        }
    }
}

This is a pretty dumb-down implementation but works for me until I can upgrade this code to net5.

I hope it helps you too!