/*
* Copyright 1999-2002,2004 The Apache Software Foundation.
*
* 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.apache.cocoon.portal.coplet.adapter.impl;
import org.apache.avalon.framework.parameters.Parameterizable;
import org.apache.avalon.framework.parameters.Parameters;
import org.apache.cocoon.components.sax.XMLByteStreamCompiler;
import org.apache.cocoon.components.sax.XMLByteStreamInterpreter;
import org.apache.cocoon.portal.coplet.CopletInstanceData;
import org.apache.cocoon.portal.event.CopletInstanceEvent;
import org.apache.cocoon.portal.event.Event;
import org.xml.sax.ContentHandler;
import org.xml.sax.SAXException;
/**
* This is the adapter to use pipelines as coplets. The result of the called
* pipeline is cached until a
* {@link org.apache.cocoon.portal.event.CopletInstanceEvent}
* for that coplet is received. Configuration options of super
* classes apply.
*
* @author <a href="mailto:gerald.kahrer@rizit.at">Gerald Kahrer</a>
*
* @version CVS $Id: CachingURICopletAdapter.java,v 1.5 2004/04/25 20:09:34 haul Exp $
*/
public class CachingURICopletAdapter
extends URICopletAdapter
implements Parameterizable {
/**
* The cache for saving the coplet data
*/
public static final String CACHE = "cacheData";
/**
* Marks the validity of the cached data
*/
public static final String CACHE_VALIDITY = "cacheValidity";
/**
* Tells the adapter to not cache the current response
*/
public static final String DO_NOT_CACHE = "doNotCache";
/**
* Marks cache valid.
*/
public static final String CACHE_VALID = "1";
/**
* Marks cache invalid
*/
public static final String CACHE_INVALID = "0";
/**
* Caching can be basically disabled with this parameter
*/
public static final String PARAMETER_DISABLE_CACHING = "disable_caching";
/**
* instance variable, that shows, if caching is disabled
*/
private boolean disableCaching = false;
/* (non-Javadoc)
* @see org.apache.avalon.framework.parameters.Parameterizable#parameterize(org.apache.avalon.framework.parameters.Parameters)
*/
public void parameterize(Parameters parameters) {
if (parameters != null) {
this.disableCaching = parameters.getParameterAsBoolean(PARAMETER_DISABLE_CACHING, false);
if (this.disableCaching) {
getLogger().info(this.getClass().getName() + " Caching is disabled.");
} else {
getLogger().info(this.getClass().getName() + " Caching is enabled.");
}
}
}
/* (non-Javadoc)
* @see org.apache.cocoon.portal.coplet.adapter.impl.AbstractCopletAdapter#streamContent(org.apache.cocoon.portal.coplet.CopletInstanceData, org.xml.sax.ContentHandler)
*/
public void streamContent(CopletInstanceData coplet, ContentHandler contentHandler)
throws SAXException {
this.streamContent( coplet, (String) coplet.getCopletData().getAttribute("uri"), contentHandler);
}
/* (non-Javadoc)
* @see org.apache.cocoon.portal.coplet.adapter.impl.URICopletAdapter#streamContent(org.apache.cocoon.portal.coplet.CopletInstanceData, java.lang.String, org.xml.sax.ContentHandler)
*/
public void streamContent( final CopletInstanceData coplet,
final String uri,
final ContentHandler contentHandler)
throws SAXException {
if (this.isValidCache(coplet)) {
this.toSAXFromCache(coplet, contentHandler);
} else {
XMLByteStreamCompiler bc = new XMLByteStreamCompiler();
super.streamContent(coplet, uri, bc);
if ( coplet.getAttribute(DO_NOT_CACHE) != null ) {
coplet.removeAttribute(DO_NOT_CACHE);
this.setCacheInvalid(coplet);
XMLByteStreamInterpreter bi = new XMLByteStreamInterpreter();
bi.setContentHandler(contentHandler);
bi.deserialize(bc.getSAXFragment());
} else {
this.toCache(coplet, bc.getSAXFragment());
this.toSAXFromCache(coplet, contentHandler);
}
}
}
/**
* Caches the data of the coplet resource in the coplet instance.
* @param coplet the coplet instance data
* @param data the data of the coplet resource
*/
private void toCache(CopletInstanceData coplet, Object data) {
coplet.setAttribute(CACHE, data);
this.setCacheValid(coplet);
}
/**
* Creates SAX events from the cached coplet data.
* @param coplet the coplet instance data
* @param contentHandler the handler, that should receive the SAX events
* @throws SAXException
*/
private void toSAXFromCache(CopletInstanceData coplet,
ContentHandler contentHandler)
throws SAXException {
XMLByteStreamInterpreter bi = new XMLByteStreamInterpreter();
bi.setContentHandler(contentHandler);
bi.deserialize(coplet.getAttribute(CACHE));
}
/**
* Tests the cache for validity.
* @param coplet the coplet instance data
*/
public boolean isValidCache(CopletInstanceData coplet) {
if (disableCaching) {
return false;
}
String cacheValidity = (String) coplet.getAttribute(CACHE_VALIDITY);
if (cacheValidity == null) {
return false;
}
return CACHE_VALID.equals(cacheValidity);
}
/**
* Sets the cache valid.
* @param coplet the coplet instance data
*/
public void setCacheValid(CopletInstanceData coplet) {
coplet.setAttribute(CACHE_VALIDITY, CACHE_VALID);
}
/**
* Sets the cache invalid.
* @param coplet the coplet instance data
*/
public void setCacheInvalid(CopletInstanceData coplet) {
coplet.setAttribute(CACHE_VALIDITY, CACHE_INVALID);
}
/* (non-Javadoc)
* @see org.apache.cocoon.portal.event.Subscriber#inform(org.apache.cocoon.portal.event.Event)
*/
public void inform(Event e) {
if (e instanceof CopletInstanceEvent) {
if ( this.getLogger().isInfoEnabled() ) {
this.getLogger().info("CopletInstanceEvent " + e + " caught by CachingURICopletAdapter");
}
this.handleCopletInstanceEvent(e);
}
super.inform(e);
}
/**
* This adapter listens for CopletInstanceEvents. Each event sets the cache invalid.
*/
public void handleCopletInstanceEvent(Event e) {
final CopletInstanceEvent event = (CopletInstanceEvent) e;
final CopletInstanceData coplet = (CopletInstanceData) event.getTarget();
this.setCacheInvalid(coplet);
}
}