/*
* Copyright 2012 JBoss, by Red Hat, Inc
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.jboss.errai.bus.server.servlet;
import static org.jboss.errai.bus.server.io.MessageFactory.createCommandMessage;
import org.jboss.errai.bus.client.api.QueueSession;
import org.jboss.errai.bus.server.QueueUnavailableException;
import org.jboss.errai.bus.server.api.MessageQueue;
import org.jboss.errai.bus.server.api.QueueActivationCallback;
import org.jboss.errai.bus.server.io.OutputStreamWriteAdapter;
import org.mortbay.jetty.RetryRequest;
import org.mortbay.util.ajax.Continuation;
import org.mortbay.util.ajax.ContinuationSupport;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.OutputStream;
/**
* The <tt>JettyContinuationsServlet</tt> provides the HTTP-protocol gateway between the server bus and the client buses,
* using Jetty Continuations.
*/
public class JettyContinuationsServlet extends AbstractErraiServlet {
/**
* Called by the server (via the <tt>service</tt> method) to allow a servlet to handle a GET request by supplying
* a response
*
* @param httpServletRequest
* - object that contains the request the client has made of the servlet
* @param httpServletResponse
* - object that contains the response the servlet sends to the client
*
* @throws IOException
* - if an input or output error is detected when the servlet handles the GET request
* @throws ServletException
* - if the request for the GET could not be handled
*/
@Override
protected void doGet(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse)
throws ServletException, IOException {
pollForMessages(sessionProvider.createOrGetSession(httpServletRequest.getSession(true),
getClientId(httpServletRequest)),
httpServletRequest, httpServletResponse, true);
}
/**
* Called by the server (via the <code>service</code> method) to allow a servlet to handle a POST request, by
* sending the request.
*
* @param httpServletRequest
* - object that contains the request the client has made of the servlet
* @param httpServletResponse
* - object that contains the response the servlet sends to the client
*
* @throws IOException
* - if an input or output error is detected when the servlet handles the request
* @throws ServletException
* - if the request for the POST could not be handled
*/
@Override
protected void doPost(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse)
throws ServletException, IOException {
final QueueSession session = sessionProvider.createOrGetSession(httpServletRequest.getSession(true),
getClientId(httpServletRequest));
session.setAttribute("NoSSE", Boolean.TRUE);
try {
service.store(createCommandMessage(session, httpServletRequest));
}
catch (QueueUnavailableException e) {
if (!session.isValid()) {
sendDisconnectDueToSessionExpiry(httpServletResponse);
}
}
pollForMessages(session, httpServletRequest, httpServletResponse, shouldWait(httpServletRequest));
}
private void pollForMessages(QueueSession session, HttpServletRequest httpServletRequest,
HttpServletResponse httpServletResponse, boolean wait) throws IOException {
final OutputStream stream = httpServletResponse.getOutputStream();
try {
final MessageQueue queue = service.getBus().getQueue(session);
if (queue == null) {
switch (getConnectionPhase(httpServletRequest)) {
case CONNECTING:
case DISCONNECTING:
return;
}
sendDisconnectDueToSessionExpiry(httpServletResponse);
return;
}
queue.heartBeat();
if (wait) {
synchronized (queue.getActivationLock()) {
final Continuation cont = ContinuationSupport.getContinuation(httpServletRequest, queue);
if (!cont.isResumed() && !queue.messagesWaiting()) {
queue.setActivationCallback(new JettyQueueActivationCallback(cont));
if (cont.suspend(30 * 1000)) {
return;
}
}
}
}
pollQueue(queue, stream, httpServletResponse);
}
catch (RetryRequest r) {
/**
* This *must* be caught and re-thrown to work property with Jetty.
*/
throw r;
}
catch (final Throwable t) {
t.printStackTrace();
httpServletResponse.setHeader("Cache-Control", "no-cache");
httpServletResponse.setHeader("Pragma", "no-cache");
httpServletResponse.setHeader("Expires", "-1");
httpServletResponse.addHeader("Payload-Size", "1");
httpServletResponse.setContentType("application/json");
StringBuilder b = new StringBuilder("{Error" +
"Message:\"").append(t.getMessage()).append("\",AdditionalDetails:\"");
for (StackTraceElement e : t.getStackTrace()) {
b.append(e.toString()).append("<br/>");
}
b.append("\"}").toString();
writeToOutputStream(stream, b.toString());
}
}
private static boolean pollQueue(MessageQueue queue, OutputStream stream,
HttpServletResponse httpServletResponse) throws IOException {
if (queue == null) return false;
queue.heartBeat();
httpServletResponse.setHeader("Cache-Control", "no-cache");
httpServletResponse.setHeader("Pragma", "no-cache");
httpServletResponse.setHeader("Expires", "-1");
httpServletResponse.setContentType("application/json");
return queue.poll(new OutputStreamWriteAdapter(stream));
}
private static class JettyQueueActivationCallback implements QueueActivationCallback {
private final Continuation cont;
private JettyQueueActivationCallback(Continuation cont) {
this.cont = cont;
}
@Override
public void activate(MessageQueue queue) {
synchronized (queue.getActivationLock()) {
queue.setActivationCallback(null);
cont.resume();
}
}
}
}