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1   /*
2    * Copyright 2012 The Netty Project
3    *
4    * The Netty Project licenses this file to you under the Apache License,
5    * version 2.0 (the "License"); you may not use this file except in compliance
6    * with the License. You may obtain a copy of the License at:
7    *
8    *   http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13   * License for the specific language governing permissions and limitations
14   * under the License.
15   */
16  package org.jboss.netty.channel;
17  
18  /**
19   * A {@link ChannelHandler} that is notified when it is added to or removed
20   * from a {@link ChannelPipeline}.
21   *
22   * <h3>Invalid access to the {@link ChannelHandlerContext}</h3>
23   *
24   * Calling {@link ChannelHandlerContext#sendUpstream(ChannelEvent)} or
25   * {@link ChannelHandlerContext#sendDownstream(ChannelEvent)} in
26   * {@link #beforeAdd(ChannelHandlerContext)} or {@link #afterRemove(ChannelHandlerContext)}
27   * might lead to an unexpected behavior.  It is because the context object
28   * might not have been fully added to the pipeline or the context object is not
29   * a part of the pipeline anymore respectively.
30   */
31  public interface LifeCycleAwareChannelHandler extends ChannelHandler {
32      void beforeAdd(ChannelHandlerContext ctx) throws Exception;
33      void afterAdd(ChannelHandlerContext ctx) throws Exception;
34      void beforeRemove(ChannelHandlerContext ctx) throws Exception;
35      void afterRemove(ChannelHandlerContext ctx) throws Exception;
36  }