SignalR and WebSocket — what is their common principle of operation, differences, and when to use?

General principle:

• WebSocket is a protocol that provides a bidirectional persistent connection between the client and server, allowing real-time data exchange.
• SignalR is a library from Microsoft that simplifies real-time communication in .NET applications, automatically selecting the best transport (WebSocket, Server-Sent Events, Long Polling) based on client and server capabilities.

Differences:

• WebSocket is a low-level protocol that requires manual implementation of message exchange logic.
• SignalR is a high-level abstraction that offers a convenient API for calling methods on the client and server, managing user groups, and automatically reconnecting.

When to use:

• Use WebSocket if you need maximum performance and control, and are ready to implement the exchange logic yourself.
• Use SignalR if you work with .NET and want to quickly add real-time functionality with minimal effort.

Example of using SignalR in C#:

public class ChatHub : Hub
{
    public async Task SendMessage(string user, string message)
    {
        await Clients.All.SendAsync("ReceiveMessage", user, message);
    }
}

This allows clients to call the SendMessage method, and the server broadcasts the message to all connected clients.