Owin Nuget 包解释

1、Install-Package Microsoft.Owin.Host.SystemWeb

OWIN server that enables OWIN-based applications to run on IIS using the ASP.NET request pipeline. 
依赖于IIS，需要配置MVC使用

2、Install-Package Microsoft.AspNet.WebApi.OwinSelfHost

This package allows you to host ASP.NET Web API within your own process using the OWIN HttpListener server. 
ASP.NET Web API is a framework that makes it easy to build HTTP services that reach a broad range of clients, including browsers and mobile devices.
ASP.NET Web API is an ideal platform for building RESTful applications on the .NET Framework.

自宿主，不需要依赖IIS，构建WebAPI，即可使用http请求服务。