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    1   package org.apache.turbine.services;
    2
    3   /*
    4    * Licensed to the Apache Software Foundation (ASF) under one
    5    * or more contributor license agreements.  See the NOTICE file
    6    * distributed with this work for additional information
    7    * regarding copyright ownership.  The ASF licenses this file
    8    * to you under the Apache License, Version 2.0 (the
    9    * "License"); you may not use this file except in compliance
    10   * with the License.  You may obtain a copy of the License at
    11   *
    12   *   http://www.apache.org/licenses/LICENSE-2.0
    13   *
    14   * Unless required by applicable law or agreed to in writing,
    15   * software distributed under the License is distributed on an
    16   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    17   * KIND, either express or implied.  See the License for the
    18   * specific language governing permissions and limitations
    19   * under the License.
    20   */
    21
    22  /**
    23   * Interface for telling Turbine that the implementation class
    24   * is an external service provider therefore can be used for looking
    25   * up services not found by the Turbine implementation. It is
    26   * assumed that the referenced service container handles the
    27   * complete lifecycle of its services.
    28   *
    29   * @author <a href="mailto:siegfried.goeschl@it20one.at">Siegfried Goeschl</a>
    30   */
    31  public interface TurbineServiceProvider
    32  {
    33      /**
    34       * Returns an instance of the requested service. If the
    35       * given service is not available/found we throw a RuntimeException
    36       * since this is less intrusive.
    37       *
    38       * @param roleName the name of the requested service
    39       * @return an instance of the service
    40       * @throws InstantiationException the service could not be instantiated
    41       */
    42      public Object get(String roleName) throws InstantiationException;
    43
    44      /**
    45       * Releases the instance you got before. This is only really
    46       * required when not working with service singletons.
    47       *
    48       * @param component the component to release
    49       */
    50      public void release(Object component);
    51
    52      /**
    53       * Is the service known to the service container?
    54       * @param roleName the name of the requested service
    55       * @return true if the service is known to the provider
    56       */
    57      public boolean exists(String roleName);
    58  }