inversion of control - ASP.NET MVC & Windsor.Castle: working with HttpContext-dependent services

Question

I have several dependency injection services which are dependent on stuff like HTTP context. Right now I'm configuring them as singletons the Windsor container in the Application_Start handler, which is obviously a problem for such services.

What is the best way to handle this? I'm considering making them transient and then releasing them after each HTTP request. But what is the best way/place to inject the HTTP context into them? Controller factory or somewhere else?

Answer 1

Just like Mark said, you need to register these http-dependent services either as PerWebRequest or Transient. Here's a sample that shows how to register and inject a HttpRequest or HttpContext:

public class Service {
    private readonly HttpRequestBase request;

    public Service(HttpRequestBase request) {
        this.request = request;
    }

    public string RawUrl {
        get {
            return request.RawUrl;
        }
    }
}

...

protected void Application_Start(object sender, EventArgs e) {
    IWindsorContainer container = new WindsorContainer();
    container.AddFacility<FactorySupportFacility>();
    container.AddComponentLifeStyle<Service>(LifestyleType.Transient);

  container.Register(Component.For<HttpRequestBase>()
      .LifeStyle.PerWebRequest
      .UsingFactoryMethod(() => new HttpRequestWrapper(HttpContext.Current.Request)));

  container.Register(Component.For<HttpContextBase>()
      .LifeStyle.PerWebRequest
      .UsingFactoryMethod(() => new HttpContextWrapper(HttpContext.Current)));  
}

By using HttpRequestBase instead of HttpRequest you can easily mock it out for testing. Also, don't forget to register PerWebRequestLifestyleModule in your web.config.