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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 io.netty.channel;
17  
18  /**
19   * {@link ChannelHandler} which adds callbacks for state changes. This allows the user
20   * to hook in to state changes easily.
21   */
22  public interface ChannelInboundHandler extends ChannelHandler {
23  
24      /**
25       * The {@link Channel} of the {@link ChannelHandlerContext} was registered with its {@link EventLoop}
26       */
27      void channelRegistered(ChannelHandlerContext ctx) throws Exception;
28  
29      /**
30       * The {@link Channel} of the {@link ChannelHandlerContext} was unregistered from its {@link EventLoop}
31       */
32      void channelUnregistered(ChannelHandlerContext ctx) throws Exception;
33  
34      /**
35       * The {@link Channel} of the {@link ChannelHandlerContext} is now active
36       */
37      void channelActive(ChannelHandlerContext ctx) throws Exception;
38  
39      /**
40       * The {@link Channel} of the {@link ChannelHandlerContext} was registered is now inactive and reached its
41       * end of lifetime.
42       */
43      void channelInactive(ChannelHandlerContext ctx) throws Exception;
44  
45      /**
46       * Invoked when the current {@link Channel} has read a message from the peer.
47       */
48      void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception;
49  
50      /**
51       * Invoked when the last message read by the current read operation has been consumed by
52       * {@link #channelRead(ChannelHandlerContext, Object)}.  If {@link ChannelOption#AUTO_READ} is off, no further
53       * attempt to read an inbound data from the current {@link Channel} will be made until
54       * {@link ChannelHandlerContext#read()} is called.
55       */
56      void channelReadComplete(ChannelHandlerContext ctx) throws Exception;
57  
58      /**
59       * Gets called if an user event was triggered.
60       */
61      void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception;
62  
63      /**
64       * Gets called once the writable state of a {@link Channel} changed. You can check the state with
65       * {@link Channel#isWritable()}.
66       */
67      void channelWritabilityChanged(ChannelHandlerContext ctx) throws Exception;
68  
69      /**
70       * Gets called if a {@link Throwable} was thrown.
71       */
72      @Override
73      @SuppressWarnings("deprecated")
74      void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception;
75  }