framework/src/main/java/org/osgi/framework/ServiceRegistration.java

/*
 * Copyright (c) OSGi Alliance (2000, 2010). 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;

import java.util.Dictionary;

/**
 * A registered service.
 * 
 * <p>
 * The Framework returns a {@code ServiceRegistration} object when a
 * {@code BundleContext.registerService} method invocation is successful.
 * The {@code ServiceRegistration} object is for the private use of the
 * registering bundle and should not be shared with other bundles.
 * <p>
 * The {@code ServiceRegistration} object may be used to update the
 * properties of the service or to unregister the service.
 * 
 * @param <S> Type of Service.
 * @see BundleContext#registerService(String[],Object,Dictionary)
 * @ThreadSafe
 * @noimplement
 * @version $Id: dc742ff3749821529f9ae62e05d9bd5d8eca00d7 $
 */

public interface ServiceRegistration<S> {
	/**
	 * Returns a {@code ServiceReference} object for a service being
	 * registered.
	 * <p>
	 * The {@code ServiceReference} object may be shared with other
	 * bundles.
	 * 
	 * @throws IllegalStateException If this
	 *         {@code ServiceRegistration} object has already been
	 *         unregistered.
	 * @return {@code ServiceReference} object.
	 */
	public ServiceReference<S> getReference();

	/**
	 * Updates the properties associated with a service.
	 * 
	 * <p>
	 * The {@link Constants#OBJECTCLASS} and {@link Constants#SERVICE_ID} keys
	 * cannot be modified by this method. These values are set by the Framework
	 * when the service is registered in the OSGi environment.
	 * 
	 * <p>
	 * The following steps are required to modify service properties:
	 * <ol>
	 * <li>The service's properties are replaced with the provided properties.
	 * <li>A service event of type {@link ServiceEvent#MODIFIED} is fired.
	 * </ol>
	 * 
	 * @param properties The properties for this service. See {@link Constants}
	 *        for a list of standard service property keys. Changes should not
	 *        be made to this object after calling this method. To update the
	 *        service's properties this method should be called again.
	 * 
	 * @throws IllegalStateException If this {@code ServiceRegistration}
	 *         object has already been unregistered.
	 * @throws IllegalArgumentException If {@code properties} contains
	 *         case variants of the same key name.
	 */
	public void setProperties(Dictionary<String, ? > properties);

	/**
	 * Unregisters a service. Remove a {@code ServiceRegistration} object
	 * from the Framework service registry. All {@code ServiceReference}
	 * objects associated with this {@code ServiceRegistration} object
	 * can no longer be used to interact with the service once unregistration is
	 * complete.
	 * 
	 * <p>
	 * The following steps are required to unregister a service:
	 * <ol>
	 * <li>The service is removed from the Framework service registry so that
	 * it can no longer be obtained.
	 * <li>A service event of type {@link ServiceEvent#UNREGISTERING} is fired
	 * so that bundles using this service can release their use of the service.
	 * Once delivery of the service event is complete, the
	 * {@code ServiceReference} objects for the service may no longer be
	 * used to get a service object for the service.
	 * <li>For each bundle whose use count for this service is greater than
	 * zero: <br>
	 * The bundle's use count for this service is set to zero. <br>
	 * If the service was registered with a {@link ServiceFactory} object, the
	 * {@code ServiceFactory.ungetService} method is called to release
	 * the service object for the bundle.
	 * </ol>
	 * 
	 * @throws IllegalStateException If this
	 *         {@code ServiceRegistration} object has already been
	 *         unregistered.
	 * @see BundleContext#ungetService
	 * @see ServiceFactory#ungetService
	 */
	public void unregister();
}