Bug 124444 Preview attached file in pdf will display nothing.
Description: Preview attached file in pdf will display nothing. Steps to reproduce: 1. Preview attached design file in pdf Expected result: Report content shows Actual result: Wait for 10 minutes but nothing showed at all
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/data/IDataEngine.java
{
	/**
	 * Prepare all the information that data engine needs to successfully obtain
	 * data used in the report.
	 * <p>
	 * The information includes
	 * <ul>
	 * <li>all data sources.
	 * <li>all datasets.
	 * <li>all report query definitons (including sub-query definitions)
	 * </ul> 
	 * <p>
	 * This method needs to prepare all report queries, Verifies the elements of
	 * a report query spec and provides a hint to the query to prepare and
	 * optimize an execution plan.
	 * <p>
	 * @param report the report design
	 * @param appContext - the context map that will be passed to the data engine
	 */	
	void prepare( Report report, Map appContext );
	
	/**
	 * Executes the prepared (data) execution plan of a report item. Returns an
	 * IResultSet object
     * <p>
	 * 
	 * @param the
	 *            query to be executed
	 * @return IResultSet object or null if the query is null
	 */