https://www.cnblogs.com/OceanEyes/p/thinking-in-asp-net-mvc-what-is-owin.html
https://www.cnblogs.com/OceanEyes/p/thinking-in-asp-net-mvc-what-is-katana.html
https://www.cnblogs.com/OceanEyes/p/thinking-in-asp-net-mvc-create-custom-middleware.html