/// <summary>
 /// Sets the cancell flag.
 /// </summary>
 public void Cancel()
 {
     lock (this) { _parent = null; }
 }
 /// <summary>
 /// Overloaded Constructor.
 /// </summary>
 /// <param name="parent"></param>
 /// <param name="period"></param>
 public PeriodicPresenceAnnouncer(IPresenceAnnouncement parent, long period)
 {
     _parent = parent;
     _period = period;
 }
 /// <summary>
 /// Constructor.
 /// </summary>
 /// <param name="parent"></param>
 public PeriodicPresenceAnnouncer(IPresenceAnnouncement parent)
 {
     _parent = parent;
 }
		/// <summary>
		/// Sets the cancell flag.
		/// </summary>
		public void Cancel()
		{
			lock (this) { _parent = null; }
		}
		/// <summary>
		/// Overloaded Constructor.
		/// </summary>
		/// <param name="parent"></param>
		/// <param name="period"></param>
		public PeriodicPresenceAnnouncer(IPresenceAnnouncement parent, long period)
		{
			_parent = parent;
			_period = period;
		}
		/// <summary>
		/// Constructor.
		/// </summary>
		/// <param name="parent"></param>
		public PeriodicPresenceAnnouncer(IPresenceAnnouncement parent)
		{
			_parent = parent;
		}