Bug 168305 IsHostPage doesn't work for birt:report tag.[0603]
viewer/org.eclipse.birt.report.viewer/birt/WEB-INF/classes/org/eclipse/birt/report/taglib/AbstractViewerTag.java
throw new JspTagException( BirtResources
					.getMessage( ResourceConstants.TAGLIB_INVALID_VIEWER_ID ) );
		}
		
		if ( pageContext.findAttribute( viewer.getId( ) ) != null )
		{
			throw new JspTagException( BirtResources
					.getMessage( ResourceConstants.TAGLIB_VIEWER_ID_DUPLICATE ) );
		}
		
		if ( viewer.getReportDesign( ) == null
				&& viewer.getReportDocument( ) == null )
		{
			throw new JspTagException( BirtResources
					.getMessage( ResourceConstants.TAGLIB_NO_REPORT_SOURCE ) );
		}
		
		if ( viewer.getReportletId( ) != null
				&& viewer.getReportDocument( ) == null )
		{
			throw new JspTagException( BirtResources
					.getMessage( ResourceConstants.TAGLIB_NO_REPORT_DOCUMENT ) );
		}
	}
	/**
	 * Validate the viewer id. Viewer id only can include number, letter and
	 * underline
	 * 
	 * @return
	 */