01: /*_############################################################################
02: _##
03: _## SNMP4J - MessageLengthDecoder.java
04: _##
05: _## Copyright (C) 2003-2008 Frank Fock and Jochen Katz (SNMP4J.org)
06: _##
07: _## Licensed under the Apache License, Version 2.0 (the "License");
08: _## you may not use this file except in compliance with the License.
09: _## You may obtain a copy of the License at
10: _##
11: _## http://www.apache.org/licenses/LICENSE-2.0
12: _##
13: _## Unless required by applicable law or agreed to in writing, software
14: _## distributed under the License is distributed on an "AS IS" BASIS,
15: _## WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16: _## See the License for the specific language governing permissions and
17: _## limitations under the License.
18: _##
19: _##########################################################################*/
20:
21: package org.snmp4j.transport;
22:
23: import java.nio.ByteBuffer;
24: import java.io.IOException;
25:
26: /**
27: * The <code>MessageLengthDecoder</code> needs to be implemented for connection
28: * oriented transport mappings, because those transport mappings have no message
29: * boundaries. To determine the message length, the message header is decoded
30: * in a protocol specific way.
31: *
32: * @author Frank Fock
33: * @version 1.7
34: * @since 1.7
35: */
36: public interface MessageLengthDecoder {
37:
38: /**
39: * Returns the minimum length of the header to be decoded. Typically this
40: * is a constant value.
41: * @return
42: * the minimum length in bytes.
43: */
44: int getMinHeaderLength();
45:
46: /**
47: * Returns the total message length to read (including header) and
48: * the actual header length.
49: * @param buf
50: * a ByteBuffer with a minimum of {@link #getMinHeaderLength()}.
51: * @return
52: * the total message length in bytes and the actual header length in bytes.
53: * @throws IOException
54: * if the header cannot be decoded.
55: */
56: MessageLength getMessageLength(ByteBuffer buf) throws IOException;
57:
58: }
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