/// <summary>
 /// Unsubscribe to activity polling.
 /// </summary>
 public static void UnsubscribeToActivity()
 {
     if (ActivityTimer != null)
     {
         ActivityTimer.Change(Timeout.InfiniteTimeSpan, Timeout.InfiniteTimeSpan);
         ActivityTimer.Dispose();
         ActivityTimer = null;
     }
 }
        /// <summary>
        /// Subscribe to activity polling.
        /// </summary>
        public static void SubscribeToActivity()
        {
            if (ActivityTimer == null)
            {
                ActivityTimer = new Timer(new TimerCallback(ActivityTimerCallback));
            }

            RepositoryActivityTask = null;
            ActivityTimer.Change(DefaultActivityPollingTime, DefaultActivityPollingTime);
        }