Bug 200755 [smoke]Fail to preview Crosstab after deploy BIRT in application servers.[0601][1102]
data/org.eclipse.birt.report.data.adapter/src/org/eclipse/birt/report/data/adapter/api/DataRequestSession.java
* @param useCache
	 *            If true, this method may return metadata cached in the report
	 *            design.If the cached metadata is empty then return an empty 
	 *            IResultMetaData instance. If the ReportDesignHandle does not 
	 *            have cached metadata then return null.
	 *		  	            
	 */
	public abstract IResultMetaData getDataSetMetaData(
			DataSetHandle dataSetHandle, boolean useCache )
			throws BirtException;
	
	/**
	 * Get the metadata information from the specified DataSetHandle. It will
	 * execute a query, force the cached metadata stored in the report design to
	 * be updated with the latest data set metadata read from out source. When
	 * there is any error in this action, an empty cached metadata will be
	 * inserted and an exception will be thrown out.
	 * 
	 * Since This method will change the data of model and it does not process
	 * any model change event, it is the responsible of the caller to make sure
	 * these events will be properly handled.
	 * 
	 * @param dataSetHandle
	 * @return the result metadata of specified dataSetHandle
	 * @throws BirtException
	 */
	public abstract IResultMetaData refreshMetaData( DataSetHandle dataSetHandle )
			throws BirtException;
	
	/**