/*
* 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.cocoon.acting;
import org.apache.avalon.framework.configuration.Configuration;
import org.apache.avalon.framework.configuration.ConfigurationException;
import org.apache.avalon.framework.parameters.Parameters;
import org.apache.avalon.framework.thread.ThreadSafe;
import org.apache.cocoon.environment.ObjectModelHelper;
import org.apache.cocoon.environment.Redirector;
import org.apache.cocoon.environment.Response;
import org.apache.cocoon.environment.SourceResolver;
import org.apache.commons.lang.time.DateUtils;
import org.apache.commons.lang.time.FastDateFormat;
import java.util.Calendar;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
/**
* This action adds the <code>Last-Modified</code>, <code>Expires</code> and
* <code>Cache-Control</code> HTTP headers to the response.
*
* <p>
* This action will add the <code>Last-Modified</code> header to the response
* with the time in which the request was executed, and an <code>Expires</code>
* header at a specified time difference. Additionally, it will provide an
* extra <code>Cache-Control</code> indicating the maximum age of the request
* as a delta between the expiration and last modification dates.
* </p>
* <p>
* This is useful (for example) when Cocoon is proxyied by a Web Server such
* as Apache HTTPD running mod_cache, to indicate for each request how long
* the output should be cached for.
* </p>
* <p>
* To configure the difference between <code>Last-Modified</code> and
* <code>Expires</code> this <code>Action</code> can be configured specifying
* days, hours, minutes, and seconds in this way:
* </p>
* <pre>
* <map:action>s
* <map:action name="xyz" src="org.apache.cocoon.acting.HttpCacheAction>"
* <days>1</day>s
* <hours>2</hour>s
* <minutes>3</minute>s
* <seconds>4</second>s
* </map:actio>n
* </map:action>s
* </pre>
* <p>
* Using this example configuration, the <code>Expires</code> header will
* specify a date one day, two hours, three minutes and four seconds after
* the time of the request (which will be in <code>Last-Modified</code>).
* </p>
* <p>
* Note that if any of the parameters mentioned above is <b>zero</b> or
* <b>less than zero</b> this action will modify the behaviour of the
* resulting <code>Cache-Control</code> header to emit the keyword
* <code>no-cache</code>.
* </p>
* <p>
* This action will also return the three headers it added as sitemap
* parameters called <code>last-modified</code>, <code>expires</code> and
* <code>cache-control</code> (all lowercase).
* </p>
*
* @author <a href="mailto:pier@apache.org">Pier Fumagalli</a>
* @version CVS $Id: HttpCacheAction.java 30941 2004-07-29 19:56:58Z vgritsenko $
*/
public class HttpCacheAction extends AbstractConfigurableAction implements ThreadSafe {
private FastDateFormat formatter = null;
int days = 0;
int hours = 0;
int minutes = 0;
int seconds = 0;
public void configure(Configuration configuration)
throws ConfigurationException {
super.configure(configuration);
// RFC-822 Date with a GMT based time zone
this.formatter = FastDateFormat.getInstance("EEE, dd MMM yyyy kk:mm:ss zzz", DateUtils.UTC_TIME_ZONE);
this.days = configuration.getChild("days").getValueAsInteger(0);
this.hours = configuration.getChild("hours").getValueAsInteger(0);
this.minutes = configuration.getChild("minutes").getValueAsInteger(0);
this.seconds = configuration.getChild("seconds").getValueAsInteger(0);
}
public Map act(Redirector redirector, SourceResolver resolver,
Map objectModel, String source, Parameters parameters)
throws Exception {
Response response = ObjectModelHelper.getResponse(objectModel);
Calendar calendar = Calendar.getInstance(DateUtils.UTC_TIME_ZONE);
Map values = new HashMap(3);
/* Get the current time and output as the last modified header */
String value = this.formatter.format(calendar);
long maxage = calendar.getTime().getTime();
response.setHeader("Last-Modified", value);
values.put("last-modified", value);
/* Advance the time as much as required */
calendar.add(Calendar.DATE, this.days);
calendar.add(Calendar.HOUR, this.hours);
calendar.add(Calendar.MINUTE, this.minutes);
calendar.add(Calendar.SECOND, this.seconds);
/* Recalculate time and age to see what changed */
maxage = calendar.getTime().getTime() - maxage;
/* If we got more than one second everything is quite normal */
if (maxage > 1000) {
value = this.formatter.format(calendar);
response.setHeader("Expires", value);
values.put("expires", value);
value = "max-age=" + Long.toString(maxage / 1000l);
response.setHeader("Cache-Control", value);
values.put("cache-control", value);
/* If we got less than one second (even negatives) no cache */
} else {
/* We still hold the old value from Last-Modified here */
response.setHeader("Expires", value);
values.put("expires", value);
response.setHeader("Cache-Control", "no-cache");
values.put("cache-control", "no-cache");
}
/* Return the headers */
return(Collections.unmodifiableMap(values));
}
}