• OwinHost.exe: While some will want to write a custom process to run Katana Web applications, many would prefer to simply launch a pre-built executable that can start a server and run their application. For this scenario, the Katana component suite includes OwinHost.exe. When run from within a project’s root directory, this executable will start a server (it uses the HttpListener server by default) and use conventions to find and run the user’s startup class. For more granular control, the executable provides a number of additional command line parameters.

  • K Commands: Whenever you want to run your app in command line using K* commands, you will use k run. The K command is your entry point to the runtime. To run an application you can use K run to build you can use K build, and all other commands that are about taking your application and running it.

K Commands 是 APS.NET 5 引出的，根据说明知道它是加载与启动 OWIN 组件的一个命令，那 OwinHost.exe 是什么？它其实是之前 OWIN 的实现 Katana 项目中的一个东西，这个东西是什么？看一下源码结构：

摘自 Program.cs 中的一段源代码：

using System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Globalization;
using System.IO;
using System.Linq;
using System.Reflection;
using Microsoft.Owin.Hosting;
using Microsoft.Owin.Hosting.Services;
using Microsoft.Owin.Hosting.Starter;
using Microsoft.Owin.Hosting.Utilities;
using OwinHost.Options;

namespace OwinHost
{
    public static class Program
    {
        public static void RunServer(StartOptions options)
        {
            if (options == null)
            {
                return;
            }

            string boot;
            if (!options.Settings.TryGetValue("boot", out boot)
                || string.IsNullOrWhiteSpace(boot))
            {
                options.Settings["boot"] = "Domain";
            }

            ResolveAssembliesFromDirectory(
                Path.Combine(Directory.GetCurrentDirectory(), "bin"));
            WriteLine("Starting with " + GetDisplayUrl(options));

            IServiceProvider services = ServicesFactory.Create();
            var starter = services.GetService();
            IDisposable server = starter.Start(options);

            WriteLine("Started successfully");
            WriteLine("Press Enter to exit");
            Console.ReadLine();

            WriteLine("Terminating.");

            server.Dispose();
        }
    }
}

可以看到，它其实和 Microsoft.AspNet.Hosting/Program.cs 中的配置代码很相似，但不相同，Microsoft.AspNet.Hosting 是 OWIN Host 的所有概念实现，而 OwinHost 只是一个控制台启动程序，用来加载所有的 OWIN 组件，但它不包含任何的实现，比如 Host 中的 Builder、Server、Startup 等一些操作，再看下面一张图就明白了：

对，没错，OwinHost 依赖于 Microsoft.Owin.Hosting，OwinHost 中所有的 Host 操作都在 Microsoft.Owin.Hosting 中进行完成了，说白了，OwinHost 没多少东西，就是一个开启命令，和 Microsoft.AspNet.Hosting 完全不是一个概念问题，那 OwinHost 和 K Commands 相等吗？其实也不相等，只是很类似，但这个类似点只是体现在加载 OWIN 组件的时候，OwinHost 的工作就是干这个的，并且只能干这个，而 K Commands 却不仅仅如此，它还包含了其他的一些命令管理，比如“gen”、“ef”等。