/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.sling.installer.factories.configuration.impl;
import java.util.Hashtable;
import org.apache.sling.installer.api.ResourceChangeListener;
import org.apache.sling.installer.api.tasks.InstallTaskFactory;
import org.apache.sling.installer.api.tasks.ResourceTransformer;
import org.osgi.framework.BundleContext;
import org.osgi.framework.Constants;
import org.osgi.framework.InvalidSyntaxException;
import org.osgi.framework.ServiceEvent;
import org.osgi.framework.ServiceListener;
import org.osgi.framework.ServiceReference;
import org.osgi.framework.ServiceRegistration;
import org.osgi.service.cm.ConfigurationAdmin;
import org.osgi.service.cm.ConfigurationListener;
/**
* The <code>ServicesListener</code> listens for the required services
* and starts/stops the scanners based on the availability of the
* services.
*/
public class ServicesListener {
/** Vendor of all registered services. */
public static final String VENDOR = "The Apache Software Foundation";
/** The bundle context. */
private final BundleContext bundleContext;
/** The listener for the change list handler. */
private final Listener changeHandlerListener;
/** The listener for the configuration admin. */
private final Listener configAdminListener;
/** Registration the service. */
private ServiceRegistration configTaskCreatorRegistration;
private ConfigTaskCreator configTaskCreator;
public ServicesListener(final BundleContext bundleContext) {
this.bundleContext = bundleContext;
this.changeHandlerListener = new Listener(ResourceChangeListener.class.getName());
this.configAdminListener = new Listener(ConfigurationAdmin.class.getName());
this.changeHandlerListener.start();
this.configAdminListener.start();
}
public synchronized void notifyChange() {
// check if all services are available
final ResourceChangeListener listener = (ResourceChangeListener)this.changeHandlerListener.getService();
final ConfigurationAdmin configAdmin = (ConfigurationAdmin)this.configAdminListener.getService();
if ( configAdmin != null && listener != null ) {
if ( configTaskCreator == null ) {
final Hashtable<String, String> props = new Hashtable<String, String>();
props.put(Constants.SERVICE_DESCRIPTION, "Apache Sling Configuration Install Task Factory");
props.put(Constants.SERVICE_VENDOR, VENDOR);
this.configTaskCreator = new ConfigTaskCreator(listener, configAdmin);
// start and register osgi installer service
final String [] serviceInterfaces = {
InstallTaskFactory.class.getName(),
ConfigurationListener.class.getName(),
ResourceTransformer.class.getName()
};
configTaskCreatorRegistration = this.bundleContext.registerService(serviceInterfaces, configTaskCreator, props);
}
} else {
this.stop();
}
}
private void stop() {
// unregister
if ( this.configTaskCreatorRegistration != null ) {
this.configTaskCreatorRegistration.unregister();
this.configTaskCreatorRegistration = null;
}
this.configTaskCreator = null;
}
/**
* Deactivate this listener.
*/
public void deactivate() {
this.changeHandlerListener.deactivate();
this.configAdminListener.deactivate();
this.stop();
}
protected final class Listener implements ServiceListener {
private final String serviceName;
private ServiceReference reference;
private Object service;
public Listener(final String serviceName) {
this.serviceName = serviceName;
}
public void start() {
this.retainService();
try {
bundleContext.addServiceListener(this, "("
+ Constants.OBJECTCLASS + "=" + serviceName + ")");
} catch (final InvalidSyntaxException ise) {
// this should really never happen
throw new RuntimeException("Unexpected exception occured.", ise);
}
}
public void deactivate() {
bundleContext.removeServiceListener(this);
}
public synchronized Object getService() {
return this.service;
}
private synchronized void retainService() {
if ( this.reference == null ) {
this.reference = bundleContext.getServiceReference(this.serviceName);
if ( this.reference != null ) {
this.service = bundleContext.getService(this.reference);
if ( this.service == null ) {
this.reference = null;
} else {
notifyChange();
}
}
}
}
private synchronized void releaseService() {
if ( this.reference != null ) {
this.service = null;
bundleContext.ungetService(this.reference);
this.reference = null;
notifyChange();
}
}
/**
* @see org.osgi.framework.ServiceListener#serviceChanged(org.osgi.framework.ServiceEvent)
*/
public void serviceChanged(ServiceEvent event) {
if (event.getType() == ServiceEvent.REGISTERED && this.service == null ) {
this.retainService();
} else if ( event.getType() == ServiceEvent.UNREGISTERING && this.service != null ) {
this.releaseService();
}
}
}
}