    001    package 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>Maintainging dependencies between <code>Initables</code> during
    045     * early initalization 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 615328 2008-01-25 20:25:05Z tv $
    053     */
    054    public 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 initailized.
    066         * @param data An object to be used for initialization activities.
    067         * @exception 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 (uninitailized)
    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         * @exception InstantiationException if there was a problem
    095         * during instantiation or initialization of the Initable.
    096         */
    097        Initable getInitable(String className) throws InstantiationException;
    098    }