org.apache.mina.filter.codec.demux

Interface MessageDecoder

All Known Implementing Classes:

AbstractMessageDecoder, AddMessageDecoder, MessageDecoderAdapter, ResultMessageDecoder

public interface MessageDecoder

Decodes a certain type of messages.

We didn't provide any dispose method for MessageDecoder because it can give you performance penalty in case you have a lot of message types to handle.

Author:

Apache MINA Project

See Also:

DemuxingProtocolDecoder, MessageDecoderFactory

Field Summary

Fields

Modifier and Type	Field and Description
static MessageDecoderResult	NEED_DATA Represents a result from decodable(IoSession, IoBuffer) and decode(IoSession, IoBuffer, ProtocolDecoderOutput).
static MessageDecoderResult	NOT_OK Represents a result from decodable(IoSession, IoBuffer) and decode(IoSession, IoBuffer, ProtocolDecoderOutput).
static MessageDecoderResult	OK Represents a result from decodable(IoSession, IoBuffer) and decode(IoSession, IoBuffer, ProtocolDecoderOutput).

Method Summary

Methods

Modifier and Type	Method and Description
MessageDecoderResult	decodable(IoSession session, IoBuffer in) Checks the specified buffer is decodable by this decoder.
MessageDecoderResult	decode(IoSession session, IoBuffer in, ProtocolDecoderOutput out) Decodes binary or protocol-specific content into higher-level message objects.
void	finishDecode(IoSession session, ProtocolDecoderOutput out) Invoked when the specified session is closed while this decoder was parsing the data.

Field Detail

OK

static final MessageDecoderResult OK

Represents a result from decodable(IoSession, IoBuffer) and decode(IoSession, IoBuffer, ProtocolDecoderOutput). Please refer to each method's documentation for detailed explanation.

NEED_DATA

static final MessageDecoderResult NEED_DATA

Represents a result from decodable(IoSession, IoBuffer) and decode(IoSession, IoBuffer, ProtocolDecoderOutput). Please refer to each method's documentation for detailed explanation.

NOT_OK

static final MessageDecoderResult NOT_OK

Represents a result from decodable(IoSession, IoBuffer) and decode(IoSession, IoBuffer, ProtocolDecoderOutput). Please refer to each method's documentation for detailed explanation.

Method Detail

decodable

MessageDecoderResult decodable(IoSession session,
                             IoBuffer in)

Checks the specified buffer is decodable by this decoder.

Parameters:

session - The current session

in - The buffer containing the data to decode

Returns:

OK if this decoder can decode the specified buffer. NOT_OK if this decoder cannot decode the specified buffer. NEED_DATA if more data is required to determine if the specified buffer is decodable (OK) or not decodable NOT_OK.

decode

MessageDecoderResult decode(IoSession session,
                          IoBuffer in,
                          ProtocolDecoderOutput out)
                            throws Exception

Decodes binary or protocol-specific content into higher-level message objects. MINA invokes decode(IoSession, IoBuffer, ProtocolDecoderOutput) method with read data, and then the decoder implementation puts decoded messages into ProtocolDecoderOutput.

Parameters:

session - The current session

in - The buffer containing the data to decode

out - The instance of ProtocolDecoderOutput that will receive the decoded messages

Returns:

OK if you finished decoding messages successfully. NEED_DATA if you need more data to finish decoding current message. NOT_OK if you cannot decode current message due to protocol specification violation.

Throws:

Exception - if the read data violated protocol specification

finishDecode

void finishDecode(IoSession session,
                ProtocolDecoderOutput out)
                  throws Exception

Invoked when the specified session is closed while this decoder was parsing the data. This method is useful when you deal with the protocol which doesn't specify the length of a message such as HTTP response without content-length header. Implement this method to process the remaining data that decode(IoSession, IoBuffer, ProtocolDecoderOutput) method didn't process completely.

Parameters:

session - The current session

out - The instance of ProtocolDecoderOutput that contains the decoded messages

Throws:

Exception - if the read data violated protocol specification