/*
============================================================================
The Apache Software License, Version 1.1
============================================================================
Copyright (C) 1999-2003 The Apache Software Foundation. All rights reserved.
Redistribution and use in source and binary forms, with or without modifica-
tion, are permitted provided that the following conditions are met:
1. Redistributions of source code must retain the above copyright notice,
this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
3. The end-user documentation included with the redistribution, if any, must
include the following acknowledgment: "This product includes software
developed by the Apache Software Foundation (http://www.apache.org/)."
Alternately, this acknowledgment may appear in the software itself, if
and wherever such third-party acknowledgments normally appear.
4. The names "Apache Cocoon" and "Apache Software Foundation" must not be
used to endorse or promote products derived from this software without
prior written permission. For written permission, please contact
apache@apache.org.
5. Products derived from this software may not be called "Apache", nor may
"Apache" appear in their name, without prior written permission of the
Apache Software Foundation.
THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
APACHE SOFTWARE FOUNDATION OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLU-
DING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
This software consists of voluntary contributions made by many individuals
on behalf of the Apache Software Foundation and was originally created by
Stefano Mazzocchi <stefano@apache.org>. For more information on the Apache
Software Foundation, please see <http://www.apache.org/>.
*/
package org.apache.cocoon.components.modules.input;
import java.util.Iterator;
import java.util.Map;
import org.apache.avalon.framework.activity.Disposable;
import org.apache.avalon.framework.component.ComponentException;
import org.apache.avalon.framework.component.ComponentManager;
import org.apache.avalon.framework.component.ComponentSelector;
import org.apache.avalon.framework.component.Composable;
import org.apache.avalon.framework.configuration.Configuration;
import org.apache.avalon.framework.configuration.ConfigurationException;
import org.apache.avalon.framework.thread.ThreadSafe;
/**
* AbstractMetaModule gives you the infrastructure for easily
* deploying more "meta" InputModules i.e. InputModules that are
* composed of other InputModules. In order to get at the Logger, use
* getLogger().
*
* @author <a href="mailto:haul@apache.org">Christian Haul</a>
* @author <a href="mailto:jefft@apache.org">Jeff Turner</a>
* @version CVS $Id: AbstractMetaModule.java,v 1.6 2003/12/23 15:28:33 joerg Exp $
*/
public abstract class AbstractMetaModule extends AbstractInputModule
implements Composable, Disposable {
/** The component manager instance */
protected ComponentManager manager;
/** The cached InputModule-Selector */
protected ComponentSelector inputSelector = null;
/** The cached default InputModule */
protected InputModule input = null;
/** The default InputModule name / shorthand. Defaults to 'request-param' */
protected String defaultInput = "request-param"; // default to request parameters
/** The default InputModule configuration */
protected Configuration inputConf = null; // will become an empty configuration object
// during configure() so why bother here...
/** Is this instance initialized? */
protected boolean initialized = false;
/* Constants */
protected final static String INPUT_MODULE_SELECTOR = InputModule.ROLE+"Selector";
/* Operation codes */
private final static int OP_GET = 0;
private final static int OP_VALUES = 1;
private final static int OP_NAMES = 2;
private final static String[] OPNAME = new String[] {"GET_VALUE", "GET_VALUES", "GET_NAMES"};
/**
* Set the current <code>ComponentManager</code> instance used by this
* <code>Composable</code>.
*/
public void compose(ComponentManager manager) throws ComponentException {
this.manager=manager;
}
/**
* Initialize the meta module with exactly one other input
* module. Since "meta" modules require references to components
* of the same role, initialization cannot be done in initialize()
* when also implementing ThreadSafe since at that point the
* component selector is not yet initialized it would trigger the
* creation of a new one resulting in an endless loop of
* initializations. Therefore, every module needs to call this
* method when it first requires access to another module if the
* module itself has not been initialized. Override this method
* and dispose() to keep references to more than one module.
*/
public synchronized void lazy_initialize() {
try {
// obtain input modules
if (!this.initialized) {
this.inputSelector=(ComponentSelector) this.manager.lookup(INPUT_MODULE_SELECTOR);
if (this.inputSelector != null && this.inputSelector instanceof ThreadSafe) {
if (this.defaultInput != null) {
this.input = obtainModule(this.defaultInput);
}
} else if (!(this.inputSelector instanceof ThreadSafe) ) {
this.manager.release(this.inputSelector);
this.inputSelector = null;
}
this.initialized = true;
}
} catch (Exception e) {
if (getLogger().isWarnEnabled())
getLogger().error("A problem occurred setting up input modules :'" + e.getMessage(), e);
}
}
/**
* Dispose exactly one cached InputModule. To work on more than
* one, override this method and initialize().
*/
public void dispose() {
if (this.inputSelector != null) {
if (this.input != null)
this.inputSelector.release(this.input);
this.manager.release(this.inputSelector);
}
}
/**
* Obtain a permanent reference to an InputModule.
*/
protected InputModule obtainModule(String type) {
ComponentSelector inputSelector = this.inputSelector;
InputModule module = null;
try {
if (inputSelector == null)
inputSelector=(ComponentSelector) this.manager.lookup(INPUT_MODULE_SELECTOR);
if (inputSelector.hasComponent(type)){
if (type != null && inputSelector.hasComponent(type))
module = (InputModule) inputSelector.select(type);
if (!(module instanceof ThreadSafe) ) {
inputSelector.release(module);
module = null;
}
}
if (type != null && module == null)
if (getLogger().isWarnEnabled())
getLogger().warn("A problem occurred setting up '" + type
+"': Selector is "+(inputSelector!=null?"not ":"")
+"null, Component is "
+(inputSelector!=null && inputSelector.hasComponent(type)?"known":"unknown"));
} catch (ComponentException ce) {
if (getLogger().isWarnEnabled())
getLogger().warn("Could not obtain selector for InputModules: "+ce.getMessage());
} finally {
if (this.inputSelector == null)
this.manager.release(inputSelector);
// FIXME: Is it OK to keep a reference to the module when we release the selector?
}
return module;
}
/**
* release a permanent reference to an InputModule.
*/
protected void releaseModule(InputModule module) {
ComponentSelector inputSelector = this.inputSelector;
if (module != null) {
try {
// FIXME: Is it OK to release a module when we have released the selector before?
if (inputSelector == null)
inputSelector=(ComponentSelector) this.manager.lookup(INPUT_MODULE_SELECTOR);
inputSelector.release(module);
module = null;
} catch (ComponentException ce) {
if (getLogger().isWarnEnabled())
getLogger().warn("Could not obtain selector for InputModules: "+ce.getMessage());
} finally {
if (this.inputSelector == null)
this.manager.release(inputSelector);
}
}
}
/**
* Get names of available attributes in the specified (usually statically
* assigned) Input Module.
* @see InputModule#getAttributeNames(Configuration, Map)
*/
protected Iterator getNames(Map objectModel,
InputModule staticMod, String staticModName, Configuration staticModConf)
throws ConfigurationException {
return (Iterator) this.get(OP_NAMES, null, objectModel, staticMod, staticModName, staticModConf, null, null, null);
}
/**
* Get names of available attributes in one of the specified Input Modules
* (static or dynamic, dynamic preferred). Dynamic IM may be
* <code>null</code>.
* @see InputModule#getAttributeNames(Configuration, Map)
*/
protected Iterator getNames(Map objectModel,
InputModule staticMod, String staticModName, Configuration staticModConf,
InputModule dynamicMod, String dynamicModName, Configuration dynamicModConf)
throws ConfigurationException {
return (Iterator) this.get(OP_NAMES, null, objectModel, staticMod, staticModName, staticModConf, dynamicMod, dynamicModName, dynamicModConf);
}
/**
* Get an attribute's value from a (usually statically assigned) Input
* Module.
* @see InputModule#getAttribute(String, Configuration, Map)
*/
protected Object getValue(String attr, Map objectModel,
InputModule staticMod, String staticModName, Configuration staticModConf)
throws ConfigurationException {
return this.get(OP_GET, attr, objectModel, staticMod, staticModName, staticModConf, null, null, null);
}
/**
* Get attribute's value in one of the specified Input Modules
* (static or dynamic, dynamic preferred). Dynamic IM may be
* <code>null</code>.
* @see InputModule#getAttribute(String, Configuration, Map)
*/
protected Object getValue(String attr, Map objectModel,
InputModule staticMod, String staticModName, Configuration staticModConf,
InputModule dynamicMod, String dynamicModName, Configuration dynamicModConf)
throws ConfigurationException {
return this.get(OP_GET, attr, objectModel, staticMod, staticModName, staticModConf, dynamicMod, dynamicModName, dynamicModConf);
}
/**
* Get an attribute's values from a (usually statically assigned) Input
* Module.
* @see InputModule#getAttributeValues(String, Configuration, Map)
*/
protected Object[] getValues(String attr, Map objectModel,
InputModule staticMod, String staticModName, Configuration staticModConf)
throws ConfigurationException {
return (Object[]) this.get(OP_VALUES, attr, objectModel, staticMod, staticModName, staticModConf, null, null, null);
}
/**
* Get attribute's values in one of the specified Input Modules
* (static or dynamic, dynamic preferred). Dynamic IM may be
* <code>null</code>.
* @see InputModule#getAttributeValues(String, Configuration, Map)
*/
protected Object[] getValues(String attr, Map objectModel,
InputModule staticMod, String staticModName, Configuration staticModConf,
InputModule dynamicMod, String dynamicModName, Configuration dynamicModConf)
throws ConfigurationException {
return (Object[]) this.get(OP_VALUES, attr, objectModel, staticMod, staticModName, staticModConf, dynamicMod, dynamicModName, dynamicModConf);
}
/**
* Encapsulates use of an InputModule. Does all the lookups and so on.
* The second module (dynamic) is preferred if it has an non null name. If
* an exception is encountered, a warn message is printed and null is
* returned.
* @param op Operation to perform ({@link OP_GET}, {@link OP_NAMES}, {@link OP_VALUES}).
*
* @return Either an Object, an Object[], or an Iterator, depending on <code>op</code> param.
*/
private Object get(int op, String attr, Map objectModel,
InputModule staticMod, String staticModName, Configuration staticModConf,
InputModule dynamicMod, String dynamicModName, Configuration dynamicModConf)
throws ConfigurationException {
ComponentSelector cs = this.inputSelector;
Object value = null;
String name = null;
InputModule input = null;
Configuration conf = null;
boolean release = false;
try {
if (cs == null) {
try {
cs = (ComponentSelector) this.manager.lookup(INPUT_MODULE_SELECTOR);
} catch (ComponentException e) {
throw new ConfigurationException("Could not find MetaModule's module selector", e);
}
}
boolean useDynamic;
if (dynamicMod == null && dynamicModName == null) {
useDynamic = false;
input = staticMod;
name = staticModName;
conf = staticModConf;
} else {
useDynamic = true;
input = dynamicMod;
name = dynamicModName;
conf = dynamicModConf;
}
if (getLogger().isDebugEnabled()) {
getLogger().debug("MetaModule performing op "+OPNAME[op]+" on " +
(useDynamic?"dynamically":"statically") + " " +
(input==null?"created":"assigned") +
" module '"+name+"', using config "+dynamicModConf);
}
if (input == null) {
if (cs.hasComponent(name)) {
release = true;
try {
input = (InputModule) cs.select(name);
} catch (ComponentException e) {
throw new ConfigurationException(
"MetaModule unable to create "+
(useDynamic ? "dynamically" : "statically")+
" specified internal module '"+name+"'", e);
}
} else {
if (getLogger().isWarnEnabled())
getLogger().warn("No such InputModule: "+name);
}
}
switch (op) {
case OP_GET:
value = input.getAttribute(attr, conf, objectModel);
break;
case OP_VALUES:
value = input.getAttributeValues(attr, conf, objectModel);
break;
case OP_NAMES:
value = input.getAttributeNames(conf, objectModel);
break;
}
if (getLogger().isDebugEnabled())
getLogger().debug("using "+name+" as "+input+" for "+op+" ("+attr+") and "+conf+" gives "+value);
} finally {
if (release)
cs.release(input);
if (this.inputSelector == null)
this.manager.release(cs);
}
return value;
}
}