KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > org > apache > mina > filter > codec > demux > MessageDecoder


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.demux;
21
22 import org.apache.mina.common.ByteBuffer;
23 import org.apache.mina.common.IoSession;
24 import org.apache.mina.filter.codec.ProtocolDecoderOutput;
25
26 /**
27  * Decodes specific messages.
28  *
29  * @author The Apache Directory Project (mina-dev@directory.apache.org)
30  * @version $Rev: 555855 $, $Date: 2007-07-13 12:19:00 +0900 (금, 13 7월 2007) $
31  *
32  * @see DemuxingProtocolCodecFactory
33  * @see MessageDecoderFactory
34  */
35 public interface MessageDecoder {
36     /**
37      * Represents a result from {@link #decodable(IoSession, ByteBuffer)} and
38      * {@link #decode(IoSession, ByteBuffer, ProtocolDecoderOutput)}. Please
39      * refer to each method's documentation for detailed explanation.
40      */
41     static MessageDecoderResult OK = MessageDecoderResult.OK;
42
43     /**
44      * Represents a result from {@link #decodable(IoSession, ByteBuffer)} and
45      * {@link #decode(IoSession, ByteBuffer, ProtocolDecoderOutput)}. Please
46      * refer to each method's documentation for detailed explanation.
47      */
48     static MessageDecoderResult NEED_DATA = MessageDecoderResult.NEED_DATA;
49
50     /**
51      * Represents a result from {@link #decodable(IoSession, ByteBuffer)} and
52      * {@link #decode(IoSession, ByteBuffer, ProtocolDecoderOutput)}. Please
53      * refer to each method's documentation for detailed explanation.
54      */
55     static MessageDecoderResult NOT_OK = MessageDecoderResult.NOT_OK;
56
57     /**
58      * Checks the specified buffer is decodable by this decoder.
59      *
60      * @return {@link #OK} if this decoder can decode the specified buffer.
61      * {@link #NOT_OK} if this decoder cannot decode the specified buffer.
62      * {@link #NEED_DATA} if more data is required to determine if the
63      * specified buffer is decodable ({@link #OK}) or not decodable
64      * {@link #NOT_OK}.
65      */
66     MessageDecoderResult decodable(IoSession session, ByteBuffer in);
67
68     /**
69      * Decodes binary or protocol-specific content into higher-level message objects.
70      * MINA invokes {@link #decode(IoSession, ByteBuffer, ProtocolDecoderOutput)}
71      * method with read data, and then the decoder implementation puts decoded
72      * messages into {@link ProtocolDecoderOutput}.
73      *
74      * @return {@link #OK} if you finished decoding messages successfully.
75      * {@link #NEED_DATA} if you need more data to finish decoding current message.
76      * {@link #NOT_OK} if you cannot decode current message due to protocol specification violation.
77      *
78      * @throws Exception if the read data violated protocol specification
79      */
80     MessageDecoderResult decode(IoSession session, ByteBuffer in,
81             ProtocolDecoderOutput out) throws Exception JavaDoc;
82
83     /**
84      * Invoked when the specified <tt>session</tt> is closed while this decoder was
85      * parsing the data. This method is useful when you deal with the protocol which doesn't
86      * specify the length of a message such as HTTP response without <tt>content-length</tt>
87      * header. Implement this method to process the remaining data that
88      * {@link #decode(IoSession, ByteBuffer, ProtocolDecoderOutput)} method didn't process
89      * completely.
90      *
91      * @throws Exception if the read data violated protocol specification
92      */
93     void finishDecode(IoSession session, ProtocolDecoderOutput out)
94             throws Exception JavaDoc;
95 }
96
Popular Tags