/*
* Copyright 2011 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 java.io.IOException;
import javax.servlet.AsyncContext;
import javax.servlet.AsyncEvent;
import javax.servlet.AsyncListener;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.jboss.errai.bus.client.api.QueueSession;
import org.jboss.errai.bus.client.framework.ClientMessageBus;
import org.jboss.errai.bus.server.api.MessageQueue;
import org.jboss.errai.bus.server.api.QueueActivationCallback;
/**
* An implementation of {@link AbstractErraiServlet} leveraging asynchronous support of Servlet 3.0.
*
* @author Christian Sadilek <csadilek@redhat.com>
*/
public class StandardAsyncServlet extends AbstractErraiServlet {
private static final long serialVersionUID = 1L;
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException,
IOException {
final QueueSession session = sessionProvider.getSession(request.getSession(),
request.getHeader(ClientMessageBus.REMOTE_QUEUE_ID_HEADER));
final MessageQueue queue = service.getBus().getQueue(session);
if (queue == null) {
switch (getConnectionPhase(request)) {
case CONNECTING:
case DISCONNECTING:
return;
}
sendDisconnectDueToSessionExpiry(response.getOutputStream());
return;
}
response.setContentType("application/json");
if (queue.messagesWaiting()) {
queue.poll(false, response.getOutputStream());
return;
}
final AsyncContext asyncContext = request.startAsync();
asyncContext.addListener(new AsyncListener() {
@Override
public void onTimeout(AsyncEvent event) throws IOException {
poll(queue, asyncContext);
asyncContext.complete();
}
@Override
public void onComplete(AsyncEvent event) throws IOException {}
@Override
public void onError(AsyncEvent event) throws IOException {}
@Override
public void onStartAsync(AsyncEvent event) throws IOException {}
});
queue.setActivationCallback(new QueueActivationCallback() {
@Override
public void activate(MessageQueue queue) {
try {
poll(queue, asyncContext);
}
catch (final Throwable t) {
try {
writeExceptionToOutputStream((HttpServletResponse)asyncContext.getResponse(), t);
}
catch (IOException e) {
throw new RuntimeException("Failed to write exception to output stream", e);
}
}
finally {
asyncContext.complete();
}
}
});
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
final QueueSession session = sessionProvider.getSession(request.getSession(),
request.getHeader(ClientMessageBus.REMOTE_QUEUE_ID_HEADER));
try {
service.store(createCommandMessage(session, request));
}
catch (Exception e) {
if (!e.getMessage().contains("expired")) {
writeExceptionToOutputStream(response, e);
}
}
}
private void poll(MessageQueue queue, AsyncContext asyncContext) throws IOException {
if (queue == null) return;
queue.setActivationCallback(null);
queue.heartBeat();
queue.poll(false, asyncContext.getResponse().getOutputStream());
}
}