MTWorkHR/MTWorkHR.API/Chat/ChatHub.cs

using Microsoft.AspNetCore.SignalR;

namespace MTWorkHR.API.Chat
{
    public class ChatHubxx : Hub
    {
        public async Task SendMessage(string user, string message)
        {
            await Clients.All.SendAsync("ReceiveMessage", user, message);
        }
    }
}