/*
 * Copyright (c) OSGi Alliance (2004, 2013). 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.service.packageadmin;

import org.osgi.framework.Bundle;
import org.osgi.framework.Version;

/**
 * A required bundle.
 * 
 * Objects implementing this interface are created by the Package Admin service.
 * 
 * <p>
 * The term <i>required bundle</i> refers to a resolved bundle that has a bundle
 * symbolic name and is not a fragment. That is, a bundle that may be required
 * by other bundles. This bundle may or may not be currently required by other
 * bundles.
 * 
 * <p>
 * The information about a required bundle provided by this object may change. A
 * {@code RequiredBundle} object becomes stale if an exported package of
 * the bundle it references has been updated or removed as a result of calling
 * {@code PackageAdmin.refreshPackages()}).
 * 
 * If this object becomes stale, its {@code getSymbolicName()} and
 * {@code getVersion()} methods continue to return their original values,
 * {@code isRemovalPending()} returns true, and {@code getBundle()}
 * and {@code getRequiringBundles()} return {@code null}.
 * 
 * @since 1.2
 * @ThreadSafe
 * @noimplement
 * @deprecated The PackageAdmin service has been replaced by the
 *             <code>org.osgi.framework.wiring</code> package.
 * @author $Id: 08ab9c1a6f4a9af2060293d2c2972e4e07e2a238 $
 */
public interface RequiredBundle {
	/**
	 * Returns the symbolic name of this required bundle.
	 * 
	 * @return The symbolic name of this required bundle.
	 */
	public String getSymbolicName();

	/**
	 * Returns the bundle associated with this required bundle.
	 * 
	 * @return The bundle, or {@code null} if this
	 *         {@code RequiredBundle} object has become stale.
	 */
	public Bundle getBundle();

	/**
	 * Returns the bundles that currently require this required bundle.
	 * 
	 * <p>
	 * If this required bundle is required and then re-exported by another
	 * bundle then all the requiring bundles of the re-exporting bundle are
	 * included in the returned array.
	 * 
	 * @return An array of bundles currently requiring this required bundle, or
	 *         {@code null} if this {@code RequiredBundle} object
	 *         has become stale. The array will be empty if no bundles require
	 *         this required package.
	 */
	public Bundle[] getRequiringBundles();

	/**
	 * Returns the version of this required bundle.
	 * 
	 * @return The version of this required bundle, or
	 *         {@link Version#emptyVersion} if no version information is
	 *         available.
	 */
	public Version getVersion();

	/**
	 * Returns {@code true} if the bundle associated with this
	 * {@code RequiredBundle} object has been updated or uninstalled.
	 * 
	 * @return {@code true} if the required bundle has been updated or
	 *         uninstalled, or if the {@code RequiredBundle} object has
	 *         become stale; {@code false} otherwise.
	 */
	public boolean isRemovalPending();
}