Bug 182061 Data engine changes to support result set sharing
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/impl/DataEngineImpl.java
if ( existingDefn != null )
			this.dataSourceManager.addDataSource( (DataSourceRuntime) existingDefn );
		
		
		
		DataSourceRuntime newDefn = DataSourceRuntime.newInstance( dataSource,
				this );
		dataSources.put( newDefn.getName( ), newDefn );
		
		logger.exiting( DataEngineImpl.class.getName( ), "defineDataSource" );
	}
	/**
	 * Provides the definition of a data set to Data Engine. A data set must be
	 * defined using this method prior to preparing any report query that uses such data set.
	 * <br>
	 * Data sets are uniquely identified name. If specified data set has already
	 * been defined, its definition will be updated with the content of the provided DataSetDesign
	 */
	public void defineDataSet( IBaseDataSetDesign dataSet )
			throws DataException
	{
		logger.entering( DataEngineImpl.class.getName( ),
				"defineDataSet",
				dataSet == null ? null : dataSet.getName( ) );
		if ( dataSet == null )
		{
			NullPointerException e = new NullPointerException( "dataSource param cannot be null" );
			logger.logp( Level.WARNING,
					DataEngineImpl.class.getName( ),
					"defineDataSet",