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.codec;
21
22 import java.nio.ByteBuffer;
23
24 /**
25 * Decodes binary or protocol-specific data into higher-level message objects.
26 *
27 * Must be immutable, a CONTEXT will be provided per session.
28 *
29 * @param <INPUT> the incoming message to decode (the low level message, usually a {@link ByteBuffer})
30 * @param <OUTPUT> the decoded message (your high level protocol Pojo/DTO)
31 * @param <DECODING_STATE> the context where to save the current decoding state (e.g. accumulated bytes, encoding
32 * context switching..)
33 *
34 * @author <a href="http://mina.apache.org">Apache MINA Project</a>
35 *
36 */
37 public interface ProtocolDecoder<INPUT, OUTPUT, DECODING_STATE> {
38
39 /**
40 * Create a new session context for this decoder
41 *
42 * @return the newly created context
43 */
44 DECODING_STATE createDecoderState();
45
46 /**
47 * Decode binary or protocol-specific content of type <code>INPUT</code> into higher-level protocol message objects,
48 * of type OUTPUT
49 *
50 * @param input the received message to decode
51 * @param context the decoding context (will be stored in the session for the next decode call)
52 * @return the decoded message or <code>null</code> if nothing was decoded
53 */
54 OUTPUT decode(INPUT input, DECODING_STATE context);
55
56 /**
57 * Finish decoding, for example if the decoder accumulated some unused input, it should discard it, or throw an
58 * Exception
59 */
60 void finishDecode(DECODING_STATE context);
61 }