/*
* Copyright 1999-2004 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.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 1.9 2004/04/28 18:13:38 haul 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);
}
protected Object getValue(String attr, Map objectModel, ModuleHolder holder) throws ConfigurationException{
return this.getValue(attr, objectModel, holder.input, holder.name, holder.config);
}
protected Object getValue(String attr, Map objectModel, ModuleHolder staticHolder, ModuleHolder dynamicHolder) throws ConfigurationException{
return this.getValue(attr, objectModel, staticHolder.input, staticHolder.name, dynamicHolder.config);
}
protected Object[] getValues(String attr, Map objectModel, ModuleHolder holder) throws ConfigurationException{
return this.getValues(attr, objectModel, holder.input, holder.name, holder.config);
}
protected Object[] getValues(String attr, Map objectModel, ModuleHolder staticHolder, ModuleHolder dynamicHolder) throws ConfigurationException{
return this.getValues(attr, objectModel, staticHolder.input, staticHolder.name, dynamicHolder.config);
}
/**
* 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;
}
}