SinalR安装
install-package Microsoft.AspNet.SignalR
Install-Package Microsoft.Owin.Cors
SignalR的技术介绍，微软官方的不错，介绍的很全面，而且还有源码
https://docs.microsoft.com/en-us/aspnet/signalr/overview/getting-started/tutorial-high-frequency-realtime-with-signalr
源码：https://github.com/Microsoft-Web/WebCampTrainingKit/releases/tag/v2016.02.09
MVC4异步：https://docs.microsoft.com/en-us/aspnet/mvc/overview/performance/using-asynchronous-methods-in-aspnet-mvc-4