public override async Task OnConnectedAsync()
{
// Update the presence tracker
var isOnline = await _tracker.UserConncted(Context.User.GetUsername(), Context.ConnectionId);
if (isOnline)
{
await Clients.Others.SendAsync("UserIsOnline", Context.User.GetUsername());
}
// send back all connected users
var currentUSers = await _tracker.GetOnlineUsers();
await Clients.Caller.SendAsync("GetOnlineUsers", currentUSers);
}