How to use IAppBuilder-based Owin Middleware in ASP.NET 5

Question

ASP.NET 5 (aspnet vnext) is OWIN based like Katana was, but has different abstractions. Notably IAppBuilder has been replaced by IApplicationBuilder.

Answer 1

Edit: you can now use the AspNet.Hosting.Katana.Extensions package for that.

---

Here's a slightly different version, that uses AppBuilder.DefaultApp:

public static IApplicationBuilder UseOwinAppBuilder(this IApplicationBuilder app, Action configuration)
{
    if (app == null)
    {
        throw new ArgumentNullException(nameof(app));
    }

    if (configuration == null)
    {
        throw new ArgumentNullException(nameof(configuration));
    }

    return app.UseOwin(setup => setup(next =>
    {
        var builder = new AppBuilder();
        var lifetime = (IApplicationLifetime) app.ApplicationServices.GetService(typeof(IApplicationLifetime));

        var properties = new AppProperties(builder.Properties);
        properties.AppName = app.ApplicationServices.GetApplicationUniqueIdentifier();
        properties.OnAppDisposing = lifetime.ApplicationStopping;
        properties.DefaultApp = next;

        configuration(builder);

        return builder.Build, Task>>();
    }));
}

Note that referencing Microsoft.Owin makes your app incompatible with dnxcore50 (Core CLR).