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 need initialization before
026 * they can work.
027 *
028 * These classes rely also on an <code>InitableBroker</code> that
029 * ensures that there is only one instance of the class in the system,
030 * and handles dependencies between <code>Initables</code>.
031 *
032 * @author <a href="mailto:burton@apache.org">Kevin Burton</a>
033 * @author <a href="mailto:krzewski@e-point.pl">Rafal Krzewski</a>
034 * @version $Id$
035 */
036public interface Initable
037{
038    /**
039     * Provides an Initable with a reference to the InitableBroker
040     * that instantiated this object, so that it can access other
041     * Initables.
042     *
043     * @param broker The InitableBroker that instantiated this object.
044     */
045    void setInitableBroker(InitableBroker broker);
046
047    /**
048     * Performs early initialization of an Initable
049     *
050     * During the startup of the system, different objects may be
051     * passed to your class using this method.  It should ignore any
052     * objects that it doesn't need or understand.
053     *
054     * After the class changes its internal state so that getInit()
055     * returns true, this method will be called no more, and late
056     * initialization will not be performed.
057     *
058     * If your class relies on early initialization, and the object it
059     * expects was not received, you can use late initialization to
060     * throw an exception and complain.
061     *
062     * @param data An Object to use for initialization activities.
063     * @throws InitializationException if initialization of this
064     * class was not successful.
065     */
066    void init(Object data) throws InitializationException;
067
068    /**
069     * Performs late initialization of an Initable.
070     *
071     * When your class is being requested from an InitableBroker, it
072     * will call getInit(), and if it returns false, this method will
073     * be invoked.
074     *
075     * @throws InitializationException if initialization of this
076     * class was not successful.
077     */
078    void init() throws InitializationException;
079
080    /**
081     * Returns an <code>Initable</code> to an uninitialized state.
082     *
083     * <p>This method must release all resources allocated by the
084     * <code>Initable</code> implementation, and resetting its internal state.
085     * You may chose to implement this operation or not. If you support
086     * this operation, getInit() should return false after successful
087     * shutdown of the service.
088     */
089    void shutdown();
090
091    /**
092     * Returns initialization status of an Initable.
093     *
094     * @return Initialization status of an Initable.
095     */
096    boolean getInit();
097}