Bug 182680 Use feature of new Aggregation framework of Data Engine.
DataEngine will implement new aggregation framework in 2.2.0RC0. After the implementation is finished Engine should go ahead to use new column bindings in definition of map/highlight.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/api/impl/EngineLogger.java
Logger rootLogger = Logger.getLogger( BIRT_NAME_SPACE );
			rootLogger.setLevel( newLevel );
		}
	}
	
	/**
	 * This is a utility function that will create an unique file name with the timestamp information in the file name and
	 * append the file name into the directory name.
	 * For example, if the directory name is C:\Log, the returned file name will be C:\Log\ReportEngine_2005_02_26_11_26_56.log.
	 * @param directoryName - the directory name of the log file. 
	 * @return An unique Log file name which is the directory name plus the file name.
	 */
	private static String generateUniqueLogFileName( String directoryName )
	{
		SimpleDateFormat df = new SimpleDateFormat("yyyy_MM_dd_HH_mm_ss"); 
		String dateTimeString = df.format( new Date() );
		
		if ( directoryName == null )
			directoryName = ""; 
		else if ( directoryName.length() > 0 )
			directoryName += System.getProperty("file.separator"); 
		
		return new String( directoryName + "ReportEngine_" + dateTimeString + ".log" ); 
	}
	private static Logger createFileLogger( String dirName )
	{
		try
		{
			Handler logFileHandler = new FileHandler(
					generateUniqueLogFileName( dirName ), true );