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 * @param session The current Session
48 * @param in the buffer to decode
49 * @param out The {@link ProtocolDecoderOutput} that will receive the decoded message
50 * @throws Exception if the read data violated protocol specification
51 */
52 void decode(IoSession session, IoBuffer in, ProtocolDecoderOutput out) throws Exception;
53
54 /**
55 * Invoked when the specified <tt>session</tt> is closed. This method is useful
56 * when you deal with the protocol which doesn't specify the length of a message
57 * such as HTTP response without <tt>content-length</tt> header. Implement this
58 * method to process the remaining data that {@link #decode(IoSession, IoBuffer, ProtocolDecoderOutput)}
59 * method didn't process completely.
60 *
61 * @param session The current Session
62 * @param out The {@link ProtocolDecoderOutput} that contains the decoded message
63 * @throws Exception if the read data violated protocol specification
64 */
65 void finishDecode(IoSession session, ProtocolDecoderOutput out) throws Exception;
66
67 /**
68 * Releases all resources related with this decoder.
69 *
70 * @param session The current Session
71 * @throws Exception if failed to dispose all resources
72 */
73 void dispose(IoSession session) throws Exception;
74 }