private async Task SendMessage(Message message, List <FileModel> attachments, Guid stamp) { var dto = Dto.CreateMessage(message, attachments); var ack = Dto.CreateMessageAck(message, stamp); await Task.WhenAll( Clients.OthersInGroup($"R{message.RoomId}").SendAsync("NewMessage", dto), Clients.Caller.SendAsync("MessageAck", ack) ); }