Hub

At the core level of SignalR sits something called a PersistentConnection class; hubs build on top of this. We won't be covering PersistentConnection as it is far more convenient to be working with the hub. In my opinion, a hub is the preferred abstraction to use; most applications really don't need to go any lower than this. It provides functionality to define functionality on the server in a C# class, much like an MVC or a Web API controller with the exception of it being persistently connected, leaving it possible to also call functionality on the client as well. The clients consume the hub and can directly call the methods on them. However, these clients can also register the client functions it responds to and create a subscription from the client that makes it respond to what it registered when the server calls it.