/*
* 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.axis.providers.java;
// currently part of Cocoon until it's officially in Axis CVS (BZ#12903)
package org.apache.cocoon.components.axis.providers;
import org.apache.avalon.framework.component.Component;
import org.apache.avalon.framework.component.ComponentManager;
import org.apache.axis.AxisFault;
import org.apache.axis.MessageContext;
import org.apache.axis.providers.java.RPCProvider;
import org.apache.axis.handlers.soap.SOAPService;
import java.lang.reflect.Method;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Proxy;
import javax.xml.rpc.server.ServiceLifecycle;
/**
* Provider class which allows you to specify an Avalon <b>ROLE</b> for
* servicing Axis SOAP requests.
*
* <p>
* The specified <b>ROLE</b> corresponds to a particular implementation
* which is retrieved by a given Avalon <code>ComponentManager</code>.
* For more information about Avalon, see the Avalon.
* <a href="http://jakarta.apache.org/avalon">website</a>.
* </p>
*
* <p>
* To use this class, you need to add your Avalon <code>ComponentManager</code>
* instance to the <code>MessageContext</code> that is Axis uses to process
* messages with.
* </p>
*
* <p>
* To do this you could for example subclass the AxisServlet and override the
* <code>createMessageContext()</code> method adding the ComponentManager, eg:
*
* <pre>
* protected MessageContext createMessageContext(...)
* {
* MessageContext context = super.createMessageContext();
* context.setProperty(AvalonProvider.COMPONENT_MANAGER, m_manager);
* return context;
* }
* </pre>
*
* and appropriately add the AvalonProvider to the list of handlers in your
* server-config.wsdd (suggestions on how to improve this are welcomed)
* </p>
*
* <p>
* This provider will use that <code>ComponentManager</code> reference to
* retrieve objects.
* </p>
*
* <p>
* In your deployment descriptor use the following syntax:
*
* <pre>
* <service name="myservice" provider="java:Avalon">
* <parameter name="role" value="my.avalon.role.name"/>
* <parameter name="className" value="my.avalon.roles.interface.name"/>
* <parameter name="allowedMethods" value="allowed.methods"/>
* </service>
* </pre>
*
* </p>
*
* @author <a href="mailto:crafterm@apache.org">Marcus Crafter</a>
* @version CVS $Id: AvalonProvider.java,v 1.5 2004/03/05 13:01:42 bdelacretaz Exp $
*/
public class AvalonProvider extends RPCProvider
{
/**
* Constant used to retrieve the ComponentManager reference
* from the MessageContext object.
*/
public static final String COMPONENT_MANAGER = "component-manager";
/**
* Constant which represents the name of the ROLE this
* provider should <i>lookup</i> to service a request with. This is
* specified in the <parameter name="" value=""/> part of the
* deployment xml.
*/
public static final String ROLE = "role";
/**
* Returns the service object.
*
* @param msgContext the message context
* @param role the Avalon ROLE to lookup to find the service object implementation
* @return an object that implements the service
* @exception Exception if an error occurs
*/
protected Object makeNewServiceObject(
MessageContext msgContext, String role
)
throws Exception
{
ComponentManager manager =
(ComponentManager) msgContext.getProperty(COMPONENT_MANAGER);
if (manager == null)
throw new AxisFault("Could not access Avalon ComponentManager");
return decorate(manager.lookup(role), manager);
}
/**
* Helper method for decorating a <code>Component</code> with a Handler
* proxy (see below).
*
* @param object a <code>Component</code> instance
* @param manager a <code>ComponentManager</code> instance
* @return the <code>Proxy</code> wrapped <code>Component</code> instance
* @exception Exception if an error occurs
*/
private Object decorate(final Component object, final ComponentManager manager)
throws Exception
{
// obtain a list of all interfaces this object implements
Class[] interfaces = object.getClass().getInterfaces();
// add ServiceLifecycle to it
Class[] adjusted = new Class[ interfaces.length + 1 ];
System.arraycopy(interfaces, 0, adjusted, 0, interfaces.length);
adjusted[interfaces.length] = ServiceLifecycle.class;
// create a proxy implementing those interfaces
Object proxy =
Proxy.newProxyInstance(
this.getClass().getClassLoader(),
adjusted,
new Handler(object, manager)
);
// return the proxy
return proxy;
}
/**
* Return the option in the configuration that contains the service class
* name. In the Avalon case, it is the ROLE name to lookup.
*/
protected String getServiceClassNameOptionName()
{
return ROLE;
}
/**
* Get the service class description
*
* @param role the Avalon ROLE name
* @param service a <code>SOAPService</code> instance
* @param msgContext the message context
* @return service class description
* @exception AxisFault if an error occurs
*/
protected Class getServiceClass(
String role, SOAPService service, MessageContext msgContext
)
throws AxisFault
{
// Assuming ExcaliburComponentManager semantics the ROLE name is
// actually the class name, potentially with a variant following
// the class name with a '/' separator
try
{
int i;
if ((i = role.indexOf('/')) != -1)
{
return Class.forName(role.substring(0, i));
}
else
{
return Class.forName(role);
}
}
catch (ClassNotFoundException e)
{
throw new AxisFault("Couldn't create class object for role " + role, e);
}
}
/**
* <code>InvocationHandler</code> class for managing Avalon
* <code>Components</code>.
*
* <p>
* Components retrieved from an Avalon ComponentManager must be
* returned to the manager when they are no longer required.
* </p>
*
* <p>
* The returning of Components to their ComponentManager is handled
* by a Proxy class which uses the following InvocationHandler.
* </p>
*
* <p>
* Each Component returned by this Provider is wrapped inside a
* Proxy class which implements all of the Component's interfaces
* including javax.xml.rpc.server.ServiceLifecycle.
* </p>
*
* <p>
* When Axis is finished with the object returned by this provider,
* it invokes ServiceLifecycle.destroy(). This is intercepted by the
* InvocationHandler and the Component is returned at this time back
* to the ComponentManager it was retrieved from.
* </p>
*
* <p>
* <b>Note</b>, when Axis invokes ServiceLifecycle.destroy() is dependant
* on the scope of the service (ie. Request, Session & Application).
* </p>
*/
final class Handler implements InvocationHandler
{
// Constants describing the ServiceLifecycle.destroy method
private final String SL_DESTROY = "destroy";
private final Class SL_CLASS = ServiceLifecycle.class;
// Component & ComponentManager references
private final Component m_object;
private final ComponentManager m_manager;
/**
* Simple constructor, sets all internal references
*
* @param object a <code>Component</code> instance
* @param manager a <code>ComponentManager</code> instance
*/
public Handler(final Component object, final ComponentManager manager)
{
m_object = object;
m_manager = manager;
}
/**
* <code>invoke</code> method, handles all method invocations for this
* particular proxy.
*
* <p>
* Usually the invocation is passed through to the
* actual component the proxy wraps, unless the method belongs to
* the <code>ServiceLifecycle</code> interface where it is handled
* locally.
* </p>
*
* @param proxy the <code>Proxy</code> instance the method was invoked on
* @param method the invoked method <code>Method</code> object
* @param args an <code>Object[]</code> array of arguments
* @return an <code>Object</code> value or null if none
* @exception Throwable if an error occurs
*/
public Object invoke(Object proxy, Method method, Object[] args)
throws Throwable
{
// if ServiceLifecycle.destroy() called, return to CM
if (method.getDeclaringClass().equals(SL_CLASS))
{
if (method.getName().equals(SL_DESTROY))
{
m_manager.release(m_object);
}
return null;
}
else // otherwise pass call to the real object
{
return method.invoke(m_object, args);
}
}
}
}