private async Task ChatCallbackMsg(Notificationmessage m)
        {
            foreach (var client in clients)
            {
                try
                {
                    var data = string.Format("data:{0}|{1}|{2}\n\n", m.username, m.text, m.dt);
                    await client.WriteAsync(data);

                    await client.FlushAsync();

                    client.Dispose();
                }
                catch (Exception)
                {
                    StreamWriter ignore;
                    clients.TryTake(out ignore);
                }
            }
        }
 public async Task PostAsync(Notificationmessage m)
 {
     m.dt = DateTime.Now.ToString("MM/dd/yyyy HH:mm:ss");
     await ChatCallbackMsg(m);
 }