traininfoservice/banedk/MetroServlet.java

package dk.thoerup.traininfoservice.banedk;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.simpleframework.xml.Serializer;
import org.simpleframework.xml.core.Persister;

import dk.thoerup.android.traininfo.common.MetroBean;
import dk.thoerup.circuitbreaker.CircuitBreakerException;
import dk.thoerup.traininfoservice.Statistics;


public class MetroServlet extends HttpServlet {

        private static final long serialVersionUID = 1L;

        Logger logger = Logger.getLogger(MetroServlet.class.getName());
        
        MetroFetcher fetcher = new MetroFetcher();

        protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
                
                if (req.getParameter("station") == null) {
                        resp.sendError(400, "not enough parameters");
                        return;
                }                       
                
                //TODO: How should statistics be handled for the metro
                //Statistics.getInstance().incrementDepartureLookups(); 
                
                int station = Integer.parseInt( req.getParameter("station") );


                MetroBean bean;         

                try {
                        
                        bean = fetcher.cachedLookupMetroDepartures(station);
                        String xml = formatXml(bean);
                        
                        resp.setDateHeader("Expires", 0);
                        resp.setHeader("Cache-Control", "no-cache, must-revalidate");
                        resp.setContentType("text/xml");
                        resp.getWriter().print(xml);
                        
                } catch (java.io.IOException ioe) {
                        logger.warning("Metro read failed, station="+station + ". " + ioe.getMessage() );
                        //Statistics.getInstance().incrementDepartureErrors();
                        resp.sendError(500);
                        return;
                } catch (CircuitBreakerException cbe) {
                        logger.warning("Circuitbreaker - failing fast");
                        //Statistics.getInstance().incrementDepartureErrors();
                        resp.sendError(500);
                        return;
                } catch (Exception e) {                 
                        logger.log(Level.WARNING, "Unknown exception, metro-station=" +station, e);
                        Statistics.getInstance().incrementDepartureErrors();
                        resp.sendError(500);
                        return;
                }
                
                
        }
        
        String formatXml(MetroBean metro) throws ServletException {
                
                Serializer serializer = new Persister();

                ByteArrayOutputStream out = new ByteArrayOutputStream();

                try {
                        serializer.write(metro, out);
                } catch (Exception e) {
                        throw new ServletException(e);
                }
                
                return out.toString();
        }
        
}
1	package dk.thoerup.traininfoservice.banedk;
2
3	import java.io.ByteArrayOutputStream;
4	import java.io.IOException;
5	import java.util.logging.Level;
6	import java.util.logging.Logger;
7
8	import javax.servlet.ServletException;
9	import javax.servlet.http.HttpServlet;
10	import javax.servlet.http.HttpServletRequest;
11	import javax.servlet.http.HttpServletResponse;
12
13	import org.simpleframework.xml.Serializer;
14	import org.simpleframework.xml.core.Persister;
15
16	import dk.thoerup.android.traininfo.common.MetroBean;
17	import dk.thoerup.circuitbreaker.CircuitBreakerException;
18	import dk.thoerup.traininfoservice.Statistics;
19
20
21
22
23
24	public class MetroServlet extends HttpServlet {
25
26	private static final long serialVersionUID = 1L;
27
28	Logger logger = Logger.getLogger(MetroServlet.class.getName());
29
30	MetroFetcher fetcher = new MetroFetcher();
31
32	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
33
34	if (req.getParameter("station") == null) {
35	resp.sendError(400, "not enough parameters");
36	return;
37	}
38
39	//TODO: How should statistics be handled for the metro
40	//Statistics.getInstance().incrementDepartureLookups();
41
42	int station = Integer.parseInt( req.getParameter("station") );
43
44
45	MetroBean bean;
46
47	try {
48
49	bean = fetcher.cachedLookupMetroDepartures(station);
50	String xml = formatXml(bean);
51
52	resp.setDateHeader("Expires", 0);
53	resp.setHeader("Cache-Control", "no-cache, must-revalidate");
54	resp.setContentType("text/xml");
55	resp.getWriter().print(xml);
56
57	} catch (java.io.IOException ioe) {
58	logger.warning("Metro read failed, station="+station + ". " + ioe.getMessage() );
59	//Statistics.getInstance().incrementDepartureErrors();
60	resp.sendError(500);
61	return;
62	} catch (CircuitBreakerException cbe) {
63	logger.warning("Circuitbreaker - failing fast");
64	//Statistics.getInstance().incrementDepartureErrors();
65	resp.sendError(500);
66	return;
67	} catch (Exception e) {
68	logger.log(Level.WARNING, "Unknown exception, metro-station=" +station, e);
69	Statistics.getInstance().incrementDepartureErrors();
70	resp.sendError(500);
71	return;
72	}
73
74
75	}
76
77	String formatXml(MetroBean metro) throws ServletException {
78
79	Serializer serializer = new Persister();
80
81	ByteArrayOutputStream out = new ByteArrayOutputStream();
82
83	try {
84	serializer.write(metro, out);
85	} catch (Exception e) {
86	throw new ServletException(e);
87	}
88
89	return out.toString();
90	}
91
92	}