public bool enabled (CommandHandle handle)
		{
			if ( handle == null || !handle.connected () )
				return false;
			string resource = handle.getName ();
			return enabled_.ContainsKey ( resource );
		}
		public bool start (CommandHandle handle)
		{
			if ( handle == null || !handle.connected () )
				return false;
			string resource = handle.getName ();

			if ( enabled_.ContainsKey ( resource ) )
			{
				if ( enabled_ [ resource ] == handle )
					return true;
				
			} else
			{
				enabled_.Add ( resource, handle );
				ROS.Info ( "quadrotor_interface", "Enabled %s output", resource );
				return true;
			}

			return false;
		}