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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   */
20  package org.apache.mina.filter.codec;
21  
22  import org.apache.mina.core.buffer.IoBuffer;
23  import org.apache.mina.core.session.IoSession;
24  
25  /**
26   * Decodes binary or protocol-specific data into higher-level message objects.
27   * MINA invokes {@link #decode(IoSession, IoBuffer, ProtocolDecoderOutput)}
28   * method with read data, and then the decoder implementation puts decoded
29   * messages into {@link ProtocolDecoderOutput} by calling
30   * {@link ProtocolDecoderOutput#write(Object)}.
31   * <p>
32   * Please refer to
33   * <a href="../../../../../xref-examples/org/apache/mina/examples/reverser/TextLineDecoder.html"><code>TextLineDecoder</code></a>
34   * example.
35   *
36   * @author <a href="http://mina.apache.org">Apache MINA Project</a>
37   * 
38   * @see ProtocolDecoderException
39   */
40  public interface ProtocolDecoder {
41      /**
42       * Decodes binary or protocol-specific content into higher-level message objects.
43       * MINA invokes {@link #decode(IoSession, IoBuffer, ProtocolDecoderOutput)}
44       * method with read data, and then the decoder implementation puts decoded
45       * messages into {@link ProtocolDecoderOutput}.
46       *
47       * @throws Exception if the read data violated protocol specification
48       */
49      void decode(IoSession session, IoBuffer in, ProtocolDecoderOutput out) throws Exception;
50  
51      /**
52       * Invoked when the specified <tt>session</tt> is closed.  This method is useful
53       * when you deal with the protocol which doesn't specify the length of a message
54       * such as HTTP response without <tt>content-length</tt> header. Implement this
55       * method to process the remaining data that {@link #decode(IoSession, IoBuffer, ProtocolDecoderOutput)}
56       * method didn't process completely.
57       *
58       * @throws Exception if the read data violated protocol specification
59       */
60      void finishDecode(IoSession session, ProtocolDecoderOutput out) throws Exception;
61  
62      /**
63       * Releases all resources related with this decoder.
64       *
65       * @throws Exception if failed to dispose all resources
66       */
67      void dispose(IoSession session) throws Exception;
68  }