Book excerpt: Get definitive guidance on SignalR, a new library for ASP.NET developers that simplifies the process of adding real-time web functionality to your applications. Real-time web functionality enables server-side code to push content to connected clients instantly as it becomes available. With this book, Microsoft .NET developers familiar with HTML and JavaScript will gain the skills to add real-time and async communication features for web, desktop, and mobile phone applications. Topics include: Introduction to async development; HTTP and real-time communications; SignalR technology fundamentals; persistent connections and hubs; multiplatform real-time applications; advanced topics Learn how SignalR uses Websockets when supported by the browser and the server and falls back to other techniques and technologies when it is not Use the simple ASP.NET API in SignalR for creating server-to-client remote procedure calls (RPC) that call JavaScript functions in client browsers from server-side .NET code. Exploit the API for connection management (e.g. connect and disconnect events), grouping connections, and authorization.