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 05:19:00 +0200 (Fri, 13 Jul 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; 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; 95 }