/**
* View "demo event" data using JFreeCharts and cewolf tag libraries.
*
* @param req HttpServletRequest
* @param res HttpServletResponse
*/

public void viewEvents(HttpServletRequest req, HttpServletResponse res) 
throws IOException, ServletException {
try {
	Connection conn = getDatabaseConnection();
	Statement stmt = conn.createStatement();
	String query = "";

		if ("EVENT_METHOD".equals(req.getParameter("groupby"))) {
			// group by eventMethod
		query = "select count(*), method.value " + "from ascfact_demo_event fact, ascdim_page_name page, ascdim_event_method method " + "where fact.page_name = page.id and fact.event_method = method.id " + "group by method.value";
		req.getSession().setAttribute("GROUP_BY_CHECKED", "EVENT_METHOD"); 

		} else {
			// group by pageName
		query = "select count(*), page.value " + "from ascfact_demo_event fact, ascdim_page_name page, ascdim_event_method method " + "where fact.page_name = page.id and fact.event_method = method.id " + "group by page.value";
		req.getSession().setAttribute("GROUP_BY_CHECKED", "PAGE_NAME"); 
	}

	// execute the query
	ResultSet results = stmt.executeQuery(query);

	// create a JFreeChart DatasetProducer which will be rendered by the cewolf tag library
	DatasetProducer datasource = new PieChartDatasetProducer(results);
	req.setAttribute("datasource", datasource);

	// close database resources
	results.close();
	stmt.close();
	conn.close();

} catch (Exception e) {
e.printStackTrace();
throw new ServletException("Exception while creating DatasetProducer - " + e);
}

RequestDispatcher dis = req.getRequestDispatcher("demo_chart.jsp"); 
dis.forward(req, res);
}</p>