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
*/
public class EngineLogger {
	
	static private final String BIRT_NAME_SPACE = "org.eclipse.birt" ; 
	/**
	 * the handler used by "org.eclipse.birt"
	 */
	static private EngineLoggerHandler sharedHandler = null;
	/**
	 * the user defined logger.
	 */
	static private Logger userLogger = null;
	/**
	 * the user defined logger output directory.
	 */
	static private String dirName = null;
	
	/**
	 * the logger uses the file handler
	 */
	static private Logger fileLogger = null;
	
	/**
	 * This function should only called by the main application that starts BIRT. It will add a new log handler to the global BIRT logger. 
	 * @param directoryName - the directory name of the log file (e.g. C:\Log). The final file name will be the directory name plus an unique file name.
	 * 						  For example, if the directory name is C:\Log, the log file name will be something like C:\Log\ReportEngine_2005_02_26_11_26_56.log
	 * @param logLevel - the log level to be set. If logLevel is null, it will be ignored.
	 */
	public static void startEngineLogging( Logger logger, String directoryName,
			Level logLevel )