    001package org.apache.turbine.services;
    002
    003
    004/*
    005 * Licensed to the Apache Software Foundation (ASF) under one
    006 * or more contributor license agreements.  See the NOTICE file
    007 * distributed with this work for additional information
    008 * regarding copyright ownership.  The ASF licenses this file
    009 * to you under the Apache License, Version 2.0 (the
    010 * "License"); you may not use this file except in compliance
    011 * with the License.  You may obtain a copy of the License at
    012 *
    013 *   http://www.apache.org/licenses/LICENSE-2.0
    014 *
    015 * Unless required by applicable law or agreed to in writing,
    016 * software distributed under the License is distributed on an
    017 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    018 * KIND, either express or implied.  See the License for the
    019 * specific language governing permissions and limitations
    020 * under the License.
    021 */
    022
    023
    024/**
    025 * Classes that implement this interface can act as a broker for
    026 * <code>Initable</code> classes.
    027 *
    028 * Functionality provided by the broker includes:
    029 *
    030 * <ul>
    031 *
    032 * <li>Maintaining a single instance of each <code>Initable</code> in
    033 * the system.</li>
    034 *
    035 * <li>Early initialization of <code>Initables</code> during system
    036 * startup.</li>
    037 *
    038 * <li>Late initialization of <code>Initables</code> before they are
    039 * used.</li>
    040 *
    041 * <li>Providing instances of <code>Initables</code> to requesting
    042 * parties.</li>
    043 *
    044 * <li>Maintaining dependencies between <code>Initables</code> during
    045 * early initialization phases, including circular dependencies
    046 * detection.</li>
    047 *
    048 * </ul>
    049 *
    050 * @author <a href="mailto:burton@apache.org">Kevin Burton</a>
    051 * @author <a href="mailto:krzewski@e-point.pl">Rafal Krzewski</a>
    052 * @version $Id: InitableBroker.java 1773378 2016-12-09 13:19:59Z tv $
    053 */
    054public interface InitableBroker
    055{
    056    /**
    057     * Performs early initialization of an Initable class.
    058     *
    059     * If your class depends on another Initable being initialized to
    060     * perform early initialization, you should always ask your broker
    061     * to initialize the other class with the objects that are passed
    062     * to you, before you try to retrieve that Initable's instance with
    063     * getInitable().
    064     *
    065     * @param className The name of the class to be initialized.
    066     * @param data An object to be used for initialization activities.
    067     * @throws InitializationException if initialization of this
    068     * class was not successful.
    069     */
    070    void initClass(String className, Object data)
    071            throws InitializationException;
    072
    073    /**
    074     * Shutdowns an Initable class.
    075     *
    076     * This method is used to release resources allocated by an
    077     * Initable class, and return it to initial (uninitialized)
    078     * state.
    079     *
    080     * @param className The name of the class to be uninitialized.
    081     */
    082    void shutdownClass(String className);
    083
    084    /**
    085     * Provides an instance of Initable class ready to work.
    086     *
    087     * If the requested class couldn't be instatiated or initialized,
    088     * InstantiationException will be thrown.  You needn't handle this
    089     * exception in your code, since it indicates fatal
    090     * misconfigurtion of the system.
    091     *
    092     * @param className The name of the Initable requested.
    093     * @return An instance of requested Initable.
    094     * @throws InstantiationException if there was a problem
    095     * during instantiation or initialization of the Initable.
    096     */
    097    Initable getInitable(String className) throws InstantiationException;
    098}