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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  }