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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 can act as a broker for
    26   * <code>Initable</code> classes.
    27   *
    28   * Functionality provided by the broker includes:
    29   *
    30   * <ul>
    31   *
    32   * <li>Maintaining a single instance of each <code>Initable</code> in
    33   * the system.</li>
    34   *
    35   * <li>Early initialization of <code>Initables</code> during system
    36   * startup.</li>
    37   *
    38   * <li>Late initialization of <code>Initables</code> before they are
    39   * used.</li>
    40   *
    41   * <li>Providing instances of <code>Initables</code> to requesting
    42   * parties.</li>
    43   *
    44   * <li>Maintainging dependencies between <code>Initables</code> during
    45   * early initalization phases, including circular dependencies
    46   * detection.</li>
    47   *
    48   * </ul>
    49   *
    50   * @author <a href="mailto:burton@apache.org">Kevin Burton</a>
    51   * @author <a href="mailto:krzewski@e-point.pl">Rafal Krzewski</a>
    52   * @version $Id: InitableBroker.java 615328 2008-01-25 20:25:05Z tv $
    53   */
    54  public interface InitableBroker
    55  {
    56      /**
    57       * Performs early initialization of an Initable class.
    58       *
    59       * If your class depends on another Initable being initialized to
    60       * perform early initialization, you should always ask your broker
    61       * to initialize the other class with the objects that are passed
    62       * to you, before you try to retrieve that Initable's instance with
    63       * getInitable().
    64       *
    65       * @param className The name of the class to be initailized.
    66       * @param data An object to be used for initialization activities.
    67       * @exception InitializationException if initialization of this
    68       * class was not successful.
    69       */
    70      void initClass(String className, Object data)
    71              throws InitializationException;
    72
    73      /**
    74       * Shutdowns an Initable class.
    75       *
    76       * This method is used to release resources allocated by an
    77       * Initable class, and return it to initial (uninitailized)
    78       * state.
    79       *
    80       * @param className The name of the class to be uninitialized.
    81       */
    82      void shutdownClass(String className);
    83
    84      /**
    85       * Provides an instance of Initable class ready to work.
    86       *
    87       * If the requested class couldn't be instatiated or initialized,
    88       * InstantiationException will be thrown.  You needn't handle this
    89       * exception in your code, since it indicates fatal
    90       * misconfigurtion of the system.
    91       *
    92       * @param className The name of the Initable requested.
    93       * @return An instance of requested Initable.
    94       * @exception InstantiationException if there was a problem
    95       * during instantiation or initialization of the Initable.
    96       */
    97      Initable getInitable(String className) throws InstantiationException;
    98  }