/*
 * Copyright (c) OSGi Alliance (2010, 2012). All Rights Reserved.
 * 
 * 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.osgi.framework.hooks.bundle;

import java.util.Collection;
import org.osgi.framework.BundleContext;
import org.osgi.framework.BundleEvent;

/**
 * OSGi Framework Bundle Event Hook Service.
 * 
 * <p>
 * Bundles registering this service will be called during framework lifecycle
 * (install, start, stop, update, and uninstall bundle) operations.
 * 
 * @ThreadSafe
 * @version $Id: e1471b36491a02bd8598a30d05c889ee58edc760 $
 */
public interface EventHook {

	/**
	 * Bundle event hook method. This method is called prior to bundle event
	 * delivery when a bundle is installed, resolved, started, stopped,
	 * unresolved, or uninstalled. This method can filter the bundles which
	 * receive the event.
	 * <p>
	 * This method must be called by the framework one and only one time for
	 * each bundle event generated, this included bundle events which are
	 * generated when there are no bundle listeners registered. This method must
	 * be called on the same thread that is performing the action which
	 * generated the specified event. The specified collection includes bundle
	 * contexts with synchronous and asynchronous bundle listeners registered
	 * with them.
	 * 
	 * @param event The bundle event to be delivered
	 * @param contexts A collection of Bundle Contexts for bundles which have
	 *        listeners to which the specified event will be delivered. The
	 *        implementation of this method may remove bundle contexts from the
	 *        collection to prevent the event from being delivered to the
	 *        associated bundles. The collection supports all the optional
	 *        {@code Collection} operations except {@code add} and
	 *        {@code addAll}. Attempting to add to the collection will result in
	 *        an {@code UnsupportedOperationException}. The collection is not
	 *        synchronized.
	 */
	void event(BundleEvent event, Collection<BundleContext> contexts);
}
