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 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: Initable.java 615328 2008-01-25 20:25:05Z tv $
035     */
036    public 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 initailization 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         * @exception InitializationException if initilaization 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         * @exception 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    }