    001// Copyright 2010 The Apache Software Foundation
    002//
    003// Licensed under the Apache License, Version 2.0 (the "License");
    004// you may not use this file except in compliance with the License.
    005// You may obtain a copy of the License at
    006//
    007// http://www.apache.org/licenses/LICENSE-2.0
    008//
    009// Unless required by applicable law or agreed to in writing, software
    010// distributed under the License is distributed on an "AS IS" BASIS,
    011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    012// See the License for the specific language governing permissions and
    013// limitations under the License.
    014
    015package org.apache.tapestry5.ioc;
    016
    017import org.apache.tapestry5.ioc.annotations.EagerLoad;
    018import org.apache.tapestry5.services.UpdateListenerHub;
    019
    020/**
    021 * Optional interface that may be implemented by a service implementation (or even
    022 * a {@linkplain ObjectLocator#proxy(Class, Class) proxy} to give the service implementation
    023 * more control over its lifecyle.
    024 *
    025 * @since 5.2.2
    026 */
    027public interface ReloadAware
    028{
    029    /**
    030     * Invoked when Tapestry {@linkplain UpdateListenerHub#fireCheckForUpdates() notices
    031     * that the implementation class has changed}. The existing instance is notified, so that
    032     * it can cleanly shutdown now, before being re-instantiated. This is necessary when the
    033     * service implementation retains some form of external resources.
    034     * <p>
    035     * In addition, the implementation may request an immediate reload. Normally, reloading of the service is deferred
    036     * until a method of the proxy object is invoked (this causes the normal just-in-time instantiation of the
    037     * implementation). When this method returns true, the implementation is re-created immediately. This is most often
    038     * the case for services that are {@linkplain EagerLoad eagerly loaded} in the first place.
    039     *
    040     * @return true if the service should be reloaded immediately, false if reload should be deferred
    041     */
    042    boolean shutdownImplementationForReload();
    043}