org.cometd.server.CometdServlet Maven / Gradle / Ivy
/*
* Copyright (c) 2008-2014 the original author or authors.
*
* 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.cometd.server;
import java.io.IOException;
import java.lang.reflect.Constructor;
import java.util.Enumeration;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.cometd.bayeux.server.BayeuxServer;
import org.cometd.bayeux.server.ServerSession;
import org.cometd.bayeux.server.ServerTransport;
import org.cometd.server.transport.HttpTransport;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* The CometD Servlet maps HTTP requests to the {@link HttpTransport} of a {@link BayeuxServer} instance.
* The {@link BayeuxServer} instance is searched in the servlet context under the {@link BayeuxServer#ATTRIBUTE}
* attribute; if it is found then it is used without further configuration, otherwise a new {@link BayeuxServer}
* instance is created and configured using the init parameters of this servlet.
* If the init parameter "transports" is present, it is treated as a comma separated list of class names, each a
* {@link ServerTransport} to be added via {@link BayeuxServerImpl#addTransport(ServerTransport)} and by default will
* be included in the {@link BayeuxServerImpl#setAllowedTransports(List)}.
* If the init parameter "allowedTransports" is present, it is treated as a comma separated list of transport names
* and will be passed to {@link BayeuxServerImpl#setAllowedTransports(List)}.
* All other init parameters are passed to {@link BayeuxServerImpl#setOption(String, Object)}.
*/
public class CometdServlet extends HttpServlet
{
private static final long serialVersionUID = 3637310585741732936L;
protected final Logger _logger = LoggerFactory.getLogger(getClass());
private volatile BayeuxServerImpl _bayeux;
@Override
public void init() throws ServletException
{
try
{
boolean export = false;
_bayeux = (BayeuxServerImpl)getServletContext().getAttribute(BayeuxServer.ATTRIBUTE);
if (_bayeux == null)
{
export = true;
_bayeux = newBayeuxServer();
String value=getInitParameter("transports");
if (value!=null)
{
ClassLoader loader = Thread.currentThread().getContextClassLoader();
if (loader == null)
loader = this.getClass().getClassLoader();
for (String className : value.split(","))
{
className = className.trim();
try
{
Class transportClass = (Class)loader.loadClass(className);
Constructor constructor = transportClass.getConstructor(BayeuxServerImpl.class);
ServerTransport transport = constructor.newInstance(_bayeux);
_bayeux.addTransport(transport);
}
catch (Throwable x)
{
_logger.warn("Failed to add transport " + className, x);
}
}
}
value=getInitParameter("allowedTransports");
if (value!=null)
{
String[] allowedTransports = value.split(",");
for (int i = 0; i < allowedTransports.length; ++i)
allowedTransports[i] = allowedTransports[i].trim();
_bayeux.setAllowedTransports(allowedTransports);
}
// Transfer all servlet init parameters to the BayeuxServer implementation
for (Enumeration initParameterNames = getInitParameterNames(); initParameterNames.hasMoreElements();)
{
String initParameterName = (String)initParameterNames.nextElement();
value = getInitParameter(initParameterName);
if (!"transports".equals(initParameterName) &&
!"allowedTransports".equalsIgnoreCase(initParameterName))
{
_bayeux.setOption(initParameterName, value);
}
}
}
_bayeux.start();
if (export)
getServletContext().setAttribute(BayeuxServer.ATTRIBUTE, _bayeux);
}
catch (Exception x)
{
throw new ServletException(x);
}
}
public BayeuxServerImpl getBayeux()
{
return _bayeux;
}
protected BayeuxServerImpl newBayeuxServer()
{
return new BayeuxServerImpl();
}
protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
{
if ("OPTIONS".equals(request.getMethod()))
{
serviceOptions(request, response);
return;
}
HttpTransport transport = null;
for (String transportName : _bayeux.getAllowedTransports())
{
ServerTransport serverTransport = _bayeux.getTransport(transportName);
if (serverTransport instanceof HttpTransport)
{
HttpTransport t = (HttpTransport)serverTransport;
if (t.accept(request))
{
transport = t;
break;
}
}
}
if (transport == null)
{
response.sendError(HttpServletResponse.SC_BAD_REQUEST, "Unknown Bayeux Transport");
}
else
{
try
{
_bayeux.setCurrentTransport(transport);
transport.setCurrentRequest(request);
transport.handle(request, response);
}
finally
{
transport.setCurrentRequest(null);
BayeuxServerImpl bayeux = _bayeux;
if (bayeux != null)
bayeux.setCurrentTransport(null);
}
}
}
protected void serviceOptions(HttpServletRequest request, HttpServletResponse response)
{
// OPTIONS requests are made by browsers that are CORS compliant
// (see http://www.w3.org/TR/cors/) during a "preflight request".
// Preflight requests happen for each different new URL, then results are cached
// by the browser.
// For the Bayeux protocol, preflight requests happen for URLs such as
// "/cometd/handshake", "/cometd/connect", etc, since the Bayeux clients append
// the Bayeux message type to the base Bayeux server URL.
// Just return 200 OK, there is nothing more to add to such requests.
}
/**
* @see javax.servlet.GenericServlet#destroy()
*/
@Override
public void destroy()
{
for (ServerSession session : _bayeux.getSessions())
((ServerSessionImpl)session).cancelSchedule();
try
{
_bayeux.stop();
}
catch (Exception x)
{
_logger.debug("", x);
}
finally
{
_bayeux = null;
getServletContext().removeAttribute(BayeuxServer.ATTRIBUTE);
}
}
}
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