SignalR's main goal is to deliver a real-time experience over HTTP, where both clients and servers can participate in a conversation as senders and listeners at the same time (known as full-duplex communication). A client initiates the flow by starting a new connection, but after that, both types of actors are equally capable of sending and receiving bits of the conversation.

In order to deliver such an experience, SignalR comes with two distinct APIs: one called persistent connection, which we can consider to be the low-level API, and one called Hubs, which is built on top of the former and brings a higher-level set of concepts and an easier and straightforward experience for the developer. We'll talk about Hubs first as we want to make our way through the SignalR features, starting from the simplest to use to the more sophisticated.

A Hub can be seen as a set of methods exposed by a server that any client can connect to, in order to perform actions on that server or to retrieve...