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    1   package org.apache.turbine.services;
    2
    3
    4   /*
    5    * Licensed to the Apache Software Foundation (ASF) under one
    6    * or more contributor license agreements.  See the NOTICE file
    7    * distributed with this work for additional information
    8    * regarding copyright ownership.  The ASF licenses this file
    9    * to you under the Apache License, Version 2.0 (the
    10   * "License"); you may not use this file except in compliance
    11   * with the License.  You may obtain a copy of the License at
    12   *
    13   *   http://www.apache.org/licenses/LICENSE-2.0
    14   *
    15   * Unless required by applicable law or agreed to in writing,
    16   * software distributed under the License is distributed on an
    17   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    18   * KIND, either express or implied.  See the License for the
    19   * specific language governing permissions and limitations
    20   * under the License.
    21   */
    22
    23
    24  /**
    25   * Classes that implement this interface need initialization before
    26   * they can work.
    27   *
    28   * These classes rely also on an <code>InitableBroker</code> that
    29   * ensures that there is only one instance of the class in the system,
    30   * and handles dependencies between <code>Initables</code>.
    31   *
    32   * @author <a href="mailto:burton@apache.org">Kevin Burton</a>
    33   * @author <a href="mailto:krzewski@e-point.pl">Rafal Krzewski</a>
    34   * @version $Id: Initable.java 615328 2008-01-25 20:25:05Z tv $
    35   */
    36  public interface Initable
    37  {
    38      /**
    39       * Provides an Initable with a reference to the InitableBroker
    40       * that instantiated this object, so that it can access other
    41       * Initables.
    42       *
    43       * @param broker The InitableBroker that instantiated this object.
    44       */
    45      void setInitableBroker(InitableBroker broker);
    46
    47      /**
    48       * Performs early initailization of an Initable
    49       *
    50       * During the startup of the system, different objects may be
    51       * passed to your class using this method.  It should ignore any
    52       * objects that it doesn't need or understand.
    53       *
    54       * After the class changes its internal state so that getInit()
    55       * returns true, this method will be called no more, and late
    56       * initialization will not be performed.
    57       *
    58       * If your class relies on early initialization, and the object it
    59       * expects was not received, you can use late initialization to
    60       * throw an exception and complain.
    61       *
    62       * @param data An Object to use for initialization activities.
    63       * @exception InitializationException if initilaization of this
    64       * class was not successful.
    65       */
    66      void init(Object data) throws InitializationException;
    67
    68      /**
    69       * Performs late initialization of an Initable.
    70       *
    71       * When your class is being requested from an InitableBroker, it
    72       * will call getInit(), and if it returns false, this method will
    73       * be invoked.
    74       *
    75       * @exception InitializationException if initialization of this
    76       * class was not successful.
    77       */
    78      void init() throws InitializationException;
    79
    80      /**
    81       * Returns an <code>Initable</code> to an uninitialized state.
    82       *
    83       * <p>This method must release all resources allocated by the
    84       * <code>Initable</code> implementation, and resetting its internal state.
    85       * You may chose to implement this operation or not. If you support
    86       * this operation, getInit() should return false after successful
    87       * shutdown of the service.
    88       */
    89      void shutdown();
    90
    91      /**
    92       * Returns initialization status of an Initable.
    93       *
    94       * @return Initialization status of an Initable.
    95       */
    96      boolean getInit();
    97  }