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    1   /*
    2    * Licensed to the Apache Software Foundation (ASF) under one
    3    * or more contributor license agreements.  See the NOTICE file
    4    * distributed with this work for additional information
    5    * regarding copyright ownership.  The ASF licenses this file
    6    * to you under the Apache License, Version 2.0 (the
    7    * "License"); you may not use this file except in compliance
    8    * with the License.  You may obtain a copy of the License at
    9    *
    10   *   http://www.apache.org/licenses/LICENSE-2.0
    11   *
    12   * Unless required by applicable law or agreed to in writing,
    13   * software distributed under the License is distributed on an
    14   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    15   * KIND, either express or implied.  See the License for the
    16   * specific language governing permissions and limitations
    17   * under the License.
    18   */
    19  package org.apache.myfaces.orchestra.conversation;
    20
    21  import java.util.HashMap;
    22  import java.util.Map;
    23
    24  /**
    25   * Maintains a list of aspects the system might attach to a conversation instance.
    26   * <p>
    27   * Aspects are a way of extending the functionality of a class without modifying it;
    28   * it acts something like the "decorator" pattern, but with many different decorator
    29   * classes being supported at once.
    30   * <p>
    31   * In the simplest form, an Aspect can be attached to a Conversation simply as a "marker"
    32   * to indicate whether the conversation should be treated in a certain way or not.
    33   * <p>
    34   * In more sophisticated form, an Aspect can provide an API. Code that wants to
    35   * manipulate some "conversation-related" property can query the conversation for the
    36   * appropriate Aspect object, then invoke the aspect api to read or write the
    37   * Conversation instance via an implementation that is isolated from both the caller
    38   * and the Conversation.
    39   * <p>
    40   * Examples of aspects that can be attached to a conversation are:
    41   * <ul>
    42   *     <li>Timeout handling</li>
    43   *     <li>Access-scope handling</li>
    44   * </ul>
    45   */
    46  public class ConversationAspects
    47  {
    48      private Map conversationAspects = new HashMap();
    49
    50      public void addAspect(ConversationAspect aspect)
    51      {
    52          conversationAspects.put(aspect.getClass().getName(), aspect);
    53      }
    54
    55      public ConversationAspect getAspect(Class aspectClass)
    56      {
    57          return (ConversationAspect) conversationAspects.get(aspectClass.getName());
    58      }
    59  }