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===Virtual Proxy - Python===
This Sample code is from a Python Remote Method Invocation program. It is copyrighted by <b>Irmen de Jong</b> and licensed by <b>MIT</b>. The code in this example is located in the <i>Clients.py</i> file of the <b>Pyro</b> system. It allows a user to write a module containing a class to be accessed remotely. The class the user created is registered by the Pyro Name Server. The client creates proxies for the remote objects to be invoked when a call is made to the object. The Virtual Proxy pattern can be seen throughout this code file as highlighted:
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<pre>
def publish(self, subjects, msg):
self.eventservice.publish(subjects,msg)
</pre>
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===Virtual Proxy - Java===
This sample code is from the Apache Geronimo server runtime framework written in J2EE. It is copyrighted by <b>IBM</b> and licensed by <b>Apache</b>. The code in this example is located in the <i>GBeanCollectionReference.java</i> of the <b>Geronimo</b> framework. It allows a user to create their own J2EE 1.4 certified application server. It can deploy servlets, XML, and other web applications. The Virtual Proxy pattern can be seen throughout this code file as highlighted:
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/**
*
* Copyright 2003-2004 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.geronimo.gbean.runtime;
import javax.management.ObjectName;
import org.apache.geronimo.gbean.GReferenceInfo;
import org.apache.geronimo.gbean.InvalidConfigurationException;
import org.apache.geronimo.kernel.DependencyManager;
import org.apache.geronimo.kernel.Kernel;
import org.apache.geronimo.kernel.lifecycle.LifecycleAdapter;
import org.apache.geronimo.kernel.lifecycle.LifecycleListener;
/**
* @version $Rev: 71492 $ $Date: 2004-11-14 21:31:50 -0800 (Sun, 14 Nov 2004) $
*/
public class GBeanCollectionReference extends AbstractGBeanReference {
public GBeanCollectionReference(GBeanInstance gbeanInstance, GReferenceInfo referenceInfo, Kernel kernel, DependencyManager dependencyManager) throws InvalidConfigurationException {
super(gbeanInstance, referenceInfo, kernel, dependencyManager);
}
public synchronized boolean start() {
// We only need to start if there are patterns and we don't already have a proxy
if (!getPatterns().isEmpty() && getProxy() == null) {
// add a dependency on our target and create the proxy
setProxy(new ProxyCollection(getName(), getReferenceType(), getKernel().getProxyManager(), getTargets()));
}
return true;
}
public synchronized void stop() {
ProxyCollection proxy = (ProxyCollection) getProxy();
if (proxy != null) {
proxy.destroy();
setProxy(null);
}
}
protected synchronized void targetAdded(ObjectName target) {
ProxyCollection proxy = (ProxyCollection) getProxy();
if (proxy != null) {
proxy.addTarget(target);
}
}
protected synchronized void targetRemoved(ObjectName target) {
ProxyCollection proxy = (ProxyCollection) getProxy();
if (proxy != null) {
proxy.removeTarget(target);
}
}
protected LifecycleListener createLifecycleListener() {
return new LifecycleAdapter() {
public void running(ObjectName objectName) {
addTarget(objectName);
}
public void stopping(ObjectName objectName) {
removeTarget(objectName);
}
public void stopped(ObjectName objectName) {
removeTarget(objectName);
}
public void failed(ObjectName objectName) {
removeTarget(objectName);
}
public void unloaded(ObjectName objectName) {
removeTarget(objectName);
}
};
}
}
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