package org.jboss.errai.bus.server.servlet;
import com.google.inject.Singleton;
import org.apache.catalina.CometEvent;
import org.jboss.errai.bus.client.framework.MarshalledMessage;
import org.jboss.errai.bus.client.api.Message;
import org.jboss.errai.bus.server.MessageQueue;
import org.jboss.errai.bus.server.QueueActivationCallback;
import org.jboss.errai.bus.server.QueueSession;
import org.jboss.servlet.http.HttpEvent;
import org.jboss.servlet.http.HttpEventServlet;
import org.mvel2.util.StringAppender;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.OutputStream;
import java.nio.CharBuffer;
import java.util.*;
import static org.jboss.errai.bus.server.io.MessageFactory.createCommandMessage;
/**
* The <tt>JBossCometServlet</tt> provides the HTTP-protocol gateway between the server bus and the client buses,
* using JBoss Comet.
*/
@Singleton
public class JBossCometServlet extends AbstractErraiServlet implements HttpEventServlet {
private final Map<MessageQueue, QueueSession> queueToSession = new HashMap<MessageQueue, QueueSession>();
private final HashMap<QueueSession, Set<HttpEvent>> activeEvents = new HashMap<QueueSession, Set<HttpEvent>>();
private Logger log = LoggerFactory.getLogger(this.getClass());
/**
* When an event is received, it is processed accordingly. A post event will tell the servlet to wait for the
* messages, if there are messages waiting, they will be transmitted. Any errors will be handled.
*
* @param event - the Http event that occured
* @throws IOException - thrown if there is a read/write error
* @throws ServletException - thrown if a servlet error occurs
*/
public void event(final HttpEvent event) throws IOException, ServletException {
final HttpServletRequest request = event.getHttpServletRequest();
final QueueSession session = sessionProvider.getSession(request.getSession());
MessageQueue queue;
switch (event.getType()) {
case BEGIN:
boolean post = "POST".equals(request.getMethod());
queue = getQueue(session, !post);
if (queue == null) {
sendDisconnectWithReason(event.getHttpServletResponse().getOutputStream(),
"There is no queue associated with this session.");
}
synchronized (activeEvents) {
if (post) {
// do not pause incoming messages.
break;
} else if (queue.messagesWaiting()) {
transmitMessages(event.getHttpServletResponse(), queue);
event.close();
break;
}
if (!queueToSession.containsKey(queue)) {
queueToSession.put(queue, session);
}
Set<HttpEvent> events = activeEvents.get(session);
if (events == null) {
activeEvents.put(session, events = new LinkedHashSet<HttpEvent>());
}
if (events.contains(event)) {
event.close();
} else {
events.add(event);
}
}
break;
case END:
if ((queue = getQueue(session, false)) != null) {
queue.heartBeat();
}
synchronized (activeEvents) {
Set<HttpEvent> evt = activeEvents.get(session);
if (evt != null) {
evt.remove(event);
}
}
event.close();
break;
case EOF:
event.close();
break;
case TIMEOUT:
case ERROR:
queue = getQueue(session, false);
synchronized (activeEvents) {
Set<HttpEvent> evt = activeEvents.get(session);
if (evt != null) {
evt.remove(event);
}
}
if (event.getType() == HttpEvent.EventType.TIMEOUT) {
if (queue != null) queue.heartBeat();
} else {
if (queue != null) {
queueToSession.remove(queue);
service.getBus().closeQueue(session.getSessionId());
// session.invalidate();
activeEvents.remove(session);
}
log.error("An Error Occured" + event.getType());
}
event.close();
break;
case READ:
readInRequest(request);
event.close();
}
}
/**
* Receives standard HTTP requests from the public, and writes it to the response's output stream in JSON format
*
* @param req - the object that contains the request the client made of the servlet
* @param httpServletResponse - the object that contains the response the servlet returns to the client
* @throws IOException - if an input or output error occurs while the servlet is handling the HTTP request
* @throws ServletException - if the HTTP request cannot be handled
*/
@Override
protected void service(HttpServletRequest req, HttpServletResponse httpServletResponse) throws ServletException, IOException {
System.out.println(CONFIG_PROBLEM_TEXT);
httpServletResponse.setHeader("Cache-Control", "no-cache");
httpServletResponse.addHeader("Payload-Size", "1");
httpServletResponse.setContentType("application/json");
OutputStream stream = httpServletResponse.getOutputStream();
stream.write('[');
writeToOutputStream(stream, new MarshalledMessage() {
public String getSubject() {
return "ClientBusErrors";
}
public Object getMessage() {
StringBuilder b = new StringBuilder("{ErrorMessage:\"").append(CONFIG_PROBLEM_TEXT).append("\",AdditionalDetails:\"");
return b.append("\"}").toString();
}
});
stream.write(',');
writeToOutputStream(stream, new MarshalledMessage() {
public String getSubject() {
return "ClientBus";
}
public Object getMessage() {
return "{CommandType:\"Disconnect\"}";
}
});
stream.write(']');
}
private int readInRequest(HttpServletRequest request) throws IOException {
BufferedReader reader = request.getReader();
if (!reader.ready()) return 0;
StringAppender sb = new StringAppender(request.getContentLength());
CharBuffer buffer = CharBuffer.allocate(10);
int read;
while ((read = reader.read(buffer)) > 0) {
buffer.rewind();
for (; read > 0; read--) {
sb.append(buffer.get());
}
buffer.rewind();
}
int messagesSent = 0;
for (Message msg : createCommandMessage(sessionProvider.getSession(request.getSession()), sb.toString())) {
service.store(msg);
messagesSent++;
}
return messagesSent;
}
private MessageQueue getQueue(QueueSession session, boolean post) {
MessageQueue queue = service.getBus().getQueue(session.getSessionId());
if (post && queue != null && queue.getActivationCallback() == null) {
queue.setActivationCallback(new QueueActivationCallback() {
boolean resumed = false;
public void activate(MessageQueue queue) {
if (resumed) {
// log.info("Blocking");
return;
}
resumed = true;
queue.setActivationCallback(null);
// log.info("Attempt to resume queue: " + queue.hashCode());
try {
Set<HttpEvent> activeSessEvents;
QueueSession session;
session = queueToSession.get(queue);
if (session == null) {
log.error("Could not resume: No session.");
return;
}
activeSessEvents = activeEvents.get(queueToSession.get(queue));
if (activeSessEvents == null || activeSessEvents.isEmpty()) {
log.warn("No active events to resume with");
return;
}
Iterator<HttpEvent> iter = activeSessEvents.iterator();
HttpEvent et;
transmitMessages((et = iter.next()).getHttpServletResponse(), queue);
iter.remove();
et.close();
}
catch (Exception e) {
e.printStackTrace();
}
}
});
}
return queue;
}
/**
* Transmits messages from the queue to the response, by writing them to the response's output stream in JSON
* format
*
* @param httpServletResponse - the response that will contain all the messages to be transmitted
* @param queue - the queue holding the messages to be transmitted
* @throws IOException - if an input or output error occurs while the servlet is handling the HTTP request
*/
public void transmitMessages(final HttpServletResponse httpServletResponse, MessageQueue queue) throws IOException {
// log.info("Transmitting messages to client (Queue:" + queue.hashCode() + ")");
List<MarshalledMessage> messages = queue.poll(false).getMessages();
httpServletResponse.setHeader("Cache-Control", "no-cache");
httpServletResponse.addHeader("Payload-Size", String.valueOf(messages.size()));
httpServletResponse.setContentType("application/json");
OutputStream stream = httpServletResponse.getOutputStream();
Iterator<MarshalledMessage> iter = messages.iterator();
stream.write('[');
while (iter.hasNext()) {
writeToOutputStream(stream, iter.next());
if (iter.hasNext()) {
stream.write(',');
}
}
stream.write(']');
stream.flush();
// queue.heartBeat();
}
private static final class PausedEvent {
private HttpServletResponse response;
private HttpSession session;
private CometEvent event;
private PausedEvent(HttpServletResponse response, HttpSession session, CometEvent event) {
this.response = response;
this.session = session;
this.event = event;
}
public HttpServletResponse getResponse() {
return response;
}
public void setResponse(HttpServletResponse response) {
this.response = response;
}
public HttpSession getSession() {
return session;
}
public void setSession(HttpSession session) {
this.session = session;
}
public CometEvent getEvent() {
return event;
}
public void setEvent(CometEvent event) {
this.event = event;
}
}
private static final String CONFIG_PROBLEM_TEXT =
"\n\n*************************************************************************************************\n"
+ "** PROBLEM!\n"
+ "** It appears something has been incorrectly configured. In order to use ErraiBus\n"
+ "** on JBoss, you must ensure that you are using the APR connector. Also make sure \n"
+ "** hat you have added these lines to your WEB-INF/web.xml file:\n"
+ "** ---\n"
+ "** <servlet>\n" +
"** <servlet-name>JBossErraiServlet</servlet-name>\n" +
"** <servlet-class>org.jboss.errai.bus.server.servlet.JBossCometServlet</servlet-class>\n" +
"** <load-on-startup>1</load-on-startup>\n" +
"** </servlet>\n" +
"**\n" +
"** <servlet-mapping>\n" +
"** <servlet-name>JBossErraiServlet</servlet-name>\n" +
"** <url-pattern>*.erraiBus</url-pattern>\n" +
"** </servlet-mapping>\n"
+ "** ---\n"
+ "** If you have the following lines in your WEB-INF/web.xml, you must comment or remove them:\n"
+ "** ---\n"
+ "** <listener>\n" +
"** <listener-class>org.jboss.errai.bus.server.ErraiServletConfig</listener-class>\n" +
"** </listener>\n"
+ "*************************************************************************************************\n\n";
}