/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.camel.component.jetty;
import java.io.IOException;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.camel.AsyncCallback;
import org.apache.camel.Exchange;
import org.apache.camel.ExchangePattern;
import org.apache.camel.component.http.CamelServlet;
import org.apache.camel.component.http.HttpConsumer;
import org.apache.camel.component.http.HttpMessage;
import org.apache.camel.component.http.helper.HttpHelper;
import org.apache.camel.impl.DefaultExchange;
import org.eclipse.jetty.continuation.Continuation;
import org.eclipse.jetty.continuation.ContinuationSupport;
/**
* Servlet which leverage <a href="http://wiki.eclipse.org/Jetty/Feature/Continuations">Jetty Continuations</a>.
*
* @version
*/
public class CamelContinuationServlet extends CamelServlet {
static final String EXCHANGE_ATTRIBUTE_NAME = "CamelExchange";
static final String EXCHANGE_ATTRIBUTE_ID = "CamelExchangeId";
private static final long serialVersionUID = 1L;
// jetty will by default use 30000 millis as default timeout
private Long continuationTimeout;
// we must remember expired exchanges as Jetty will initiate a new continuation when we send
// back the error when timeout occurred, and thus in the async callback we cannot check the
// continuation if it was previously expired. So that's why we have our own map for that
private final Map<String, String> expiredExchanges = new ConcurrentHashMap<String, String>();
@Override
protected void service(final HttpServletRequest request, final HttpServletResponse response) throws ServletException, IOException {
log.trace("Service: {}", request);
// is there a consumer registered for the request.
HttpConsumer consumer = resolve(request);
if (consumer == null) {
response.sendError(HttpServletResponse.SC_NOT_FOUND);
return;
}
if (consumer.getEndpoint().getHttpMethodRestrict() != null
&& !consumer.getEndpoint().getHttpMethodRestrict().equals(request.getMethod())) {
response.sendError(HttpServletResponse.SC_METHOD_NOT_ALLOWED);
return;
}
if ("TRACE".equals(request.getMethod()) && !consumer.isTraceEnabled()) {
response.sendError(HttpServletResponse.SC_METHOD_NOT_ALLOWED);
return;
}
final Exchange result = (Exchange) request.getAttribute(EXCHANGE_ATTRIBUTE_NAME);
if (result == null) {
// no asynchronous result so leverage continuation
final Continuation continuation = ContinuationSupport.getContinuation(request);
if (continuation.isInitial() && continuationTimeout != null) {
// set timeout on initial
continuation.setTimeout(continuationTimeout);
}
// are we suspended and a request is dispatched initially?
if (consumer.isSuspended() && continuation.isInitial()) {
response.sendError(HttpServletResponse.SC_SERVICE_UNAVAILABLE);
return;
}
if (continuation.isExpired()) {
String id = (String) continuation.getAttribute(EXCHANGE_ATTRIBUTE_ID);
// remember this id as expired
expiredExchanges.put(id, id);
log.warn("Continuation expired of exchangeId: {}", id);
response.sendError(HttpServletResponse.SC_SERVICE_UNAVAILABLE);
return;
}
// a new request so create an exchange
final Exchange exchange = new DefaultExchange(consumer.getEndpoint(), ExchangePattern.InOut);
if (consumer.getEndpoint().isBridgeEndpoint()) {
exchange.setProperty(Exchange.SKIP_GZIP_ENCODING, Boolean.TRUE);
}
if (consumer.getEndpoint().isDisableStreamCache()) {
exchange.setProperty(Exchange.DISABLE_HTTP_STREAM_CACHE, Boolean.TRUE);
}
HttpHelper.setCharsetFromContentType(request.getContentType(), exchange);
exchange.setIn(new HttpMessage(exchange, request, response));
// set context path as header
String contextPath = consumer.getEndpoint().getPath();
exchange.getIn().setHeader("CamelServletContextPath", contextPath);
String httpPath = (String)exchange.getIn().getHeader(Exchange.HTTP_PATH);
// here we just remove the CamelServletContextPath part from the HTTP_PATH
if (contextPath != null
&& httpPath.startsWith(contextPath)) {
exchange.getIn().setHeader(Exchange.HTTP_PATH,
httpPath.substring(contextPath.length()));
}
if (log.isTraceEnabled()) {
log.trace("Suspending continuation of exchangeId: {}", exchange.getExchangeId());
}
continuation.setAttribute(EXCHANGE_ATTRIBUTE_ID, exchange.getExchangeId());
// we want to handle the UoW
try {
consumer.createUoW(exchange);
} catch (Exception e) {
log.error("Error processing request", e);
throw new ServletException(e);
}
// must suspend before we process the exchange
continuation.suspend();
ClassLoader oldTccl = overrideTccl(exchange);
if (log.isTraceEnabled()) {
log.trace("Processing request for exchangeId: {}", exchange.getExchangeId());
}
// use the asynchronous API to process the exchange
consumer.getAsyncProcessor().process(exchange, new AsyncCallback() {
public void done(boolean doneSync) {
// check if the exchange id is already expired
boolean expired = expiredExchanges.remove(exchange.getExchangeId()) != null;
if (!expired) {
if (log.isTraceEnabled()) {
log.trace("Resuming continuation of exchangeId: {}", exchange.getExchangeId());
}
// resume processing after both, sync and async callbacks
continuation.setAttribute(EXCHANGE_ATTRIBUTE_NAME, exchange);
continuation.resume();
} else {
log.warn("Cannot resume expired continuation of exchangeId: {}", exchange.getExchangeId());
}
}
});
if (oldTccl != null) {
restoreTccl(exchange, oldTccl);
}
// return to let Jetty continuation to work as it will resubmit and invoke the service
// method again when its resumed
return;
}
try {
// now lets output to the response
if (log.isTraceEnabled()) {
log.trace("Resumed continuation and writing response for exchangeId: {}", result.getExchangeId());
}
Integer bs = consumer.getEndpoint().getResponseBufferSize();
if (bs != null) {
log.trace("Using response buffer size: {}", bs);
response.setBufferSize(bs);
}
consumer.getBinding().writeResponse(result, response);
} catch (IOException e) {
log.error("Error processing request", e);
throw e;
} catch (Exception e) {
log.error("Error processing request", e);
throw new ServletException(e);
} finally {
consumer.doneUoW(result);
}
}
public Long getContinuationTimeout() {
return continuationTimeout;
}
public void setContinuationTimeout(Long continuationTimeout) {
this.continuationTimeout = continuationTimeout;
}
@Override
public void destroy() {
expiredExchanges.clear();
super.destroy();
}
}