Bug 120345 Need a URL generator API from Engine
The Chart Engine needs the ability to generate a viewer URL from an ActionHandle, this can be provided by a Report Engine public API for instance. The URL should usable as is by the viewer without any additional change. The Chart Engine can take care of evaluating the expressions inside the ActionHandle before calling the Report Engine API if necessary.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/extension/IRowSet.java
* 			0 if the result set has no groups.
     */
	int getStartingGroupLevel();
	
	/**
     * Returns the 1-based index of the outermost group
     * in which the current row is the first row. 
     * For example, if a query contain N groups 
     * (group with index 1 being the outermost group, and group with 
     * index N being the innermost group),
     * and this function returns a value M, it indicates that the 
     * current row is the first row in groups with 
     * indexes (M, M+1, ..., N ).
     * @return	1-based index of the outermost group in which 
     * 			the current row is the first row;
     * 			(N+1) if the current row is not at the start of any group;
     * 			0 if the result set has no groups.
     */
	int getEndingGroupLevel();
	
	/**
	 * evaluate the expression using current row.
	 * @param expr expression, must be prepared in DTE.prepared().
	 * @return result of the expression.
	 */
	Object evaluate(IBaseExpression expr);
	
	void close();
}