public void Dispose()
 {
     if (_ql != null)
     {
         _ql.StopListen();
         _ql = null;
     }
 }
        public string StartListen(string maxConcurrency)
        {
            int mc;

            if (int.TryParse(maxConcurrency, out mc))
            {
                if (_ql == null)
                    _ql = new Classes.QueueListener();

                _ql.StartListen(mc);

                return "OK";
            }
            else
            {
                throw new ArgumentException("'maxConcurrency' needs to be a valid integer.");
            }
        }