Bug 165188 logging per report
Setting up a dedicated (birt) report server, which serves all our web apps, leads to a logging desaster. Birtegine logs all messages to one file. There's no info which rptdesign caused the logmessage or who (e.g. user) caused the logmessage. Retrieving who/which rpt caused some logmessage is not possible! There are two possible solutions: (a) prefixing each logmessage with a userdefineable message (task.setLogprefix("myprefix")) (b) set an outputstream for each task (task.setLoggingOutputStream(outputstream)) to split the huge logfile to many small pieces.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/api/impl/EngineLogger.java
if ( directoryName == null )
			directoryName = ""; 
		else if ( directoryName.length() > 0 )
			directoryName += System.getProperty("file.separator"); 
		
		return new String( directoryName + "ReportEngine_" + dateTimeString + ".log" ); 
	}
	private static void createLogFile( Logger logger )
	{
		if ( logFileHandler != null || dirName == null )
			return;
		try {
			logFileHandler = new FileHandler( generateUniqueLogFileName(dirName), true );
		} catch (SecurityException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		
		if ( logFileHandler != null )
		{
			logFileHandler.setFormatter( new SimpleFormatter() ); 
			logFileHandler.setLevel( Level.FINEST );
			logger.addHandler( logFileHandler );
		}
		
		logger.setUseParentHandlers( false );
	}
}