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
* prepare( query, null). The default session application context is used
	 * for this query.
	 * 
	 * @param querySpec
	 *            Specifies the data access and data transforms services needed
	 *            from DtE to produce a set of query results.
	 * @return The <code>IPreparedQuery</code> object that contains a prepared
	 *         query ready for execution.
	 * @throws BirtException
	 *             if error occurs during the preparation of querySpec
	 */
	public abstract IPreparedQuery prepare( IQueryDefinition query )
			throws BirtException;
	
	/**
	 * Provides a hint to DtE that the consumer is done with the given data
	 * source, and that its resources can be safely released as appropriate.
	 * This tells DtE that there is to be no more query in this session that
	 * uses such data source.
	 * 
	 * @param dataSourceName
	 *            The name of a data source. The named data source must have
	 *            been previously defined.
	 */
	public abstract void closeDataSource( String dataSourceName )
			throws BirtException;
	
	/**
	 * Delete the cache content of the specified data set. Subsequent requests
	 * using this data set will cause its cache to be regenerated with updated