Demonstrate bi-direction communication between server and client.

EventHub.cs

using Microsoft.AspNetCore.SignalR;
using Microsoft.AspNetCore.SignalR;


namespace SignalR.Lab.Web.Hubs
{
    public interface IEventHub
    {
        // here place some method(s) for message from server to client(s) (broadcast)
        Task SendNoticeEventToClient(string message);
        
        send message from server to specific group if client registered
        //Task SendMessageToGroup(string group, string message);
    }
    
    public class EventHub : Hub<IEventHub>
    {
        // here place some method(s) for message from client to server
        // subscription or un-subscription for client(s)
        public Task JoinOrLeaveGroup(string group, bool check)
        {
            if (check)
            {
                return Groups.AddToGroupAsync(Context.ConnectionId, group);
            }
            else
            {
                return Groups.RemoveFromGroupAsync(Context.ConnectionId, group);
            }
        }
    }
}