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 }