Package org.apache.mina.filter.codec.statemachine

Class DecodingStateMachine

java.lang.Object

org.apache.mina.filter.codec.statemachine.DecodingStateMachine

All Implemented Interfaces:

DecodingState

public abstract class DecodingStateMachine
extends Object
implements DecodingState

Abstract base class for decoder state machines. Calls init() to get the start DecodingState of the state machine. Calls destroy() when the state machine has reached its end state or when the session is closed.

NOTE: The ProtocolDecoderOutput used by this class when calling DecodingState.decode(IoBuffer, ProtocolDecoderOutput) buffers decoded messages in a List. Once the state machine has reached its end state this class will call finishDecode(List, ProtocolDecoderOutput). The implementation will have to take care of writing the decoded messages to the real ProtocolDecoderOutput used by the configured ProtocolCodecFilter.

Author:

Apache MINA Project

Constructor Summary

Constructors

Constructor	Description
DecodingStateMachine()

Method Summary

Modifier and Type	Method	Description
DecodingState	decode(IoBuffer in, ProtocolDecoderOutput out)	Invoked when data is available for this state.
protected abstract void	destroy()	Invoked to destroy this state machine once the end state has been reached or the session has been closed.
protected abstract DecodingState	finishDecode(List<Object> childProducts, ProtocolDecoderOutput out)	Called once the state machine has reached its end.
DecodingState	finishDecode(ProtocolDecoderOutput out)	Invoked when the associated IoSession is closed.
protected abstract DecodingState	init()	Invoked to initialize this state machine.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

DecodingStateMachine

public DecodingStateMachine()

Method Detail

init

protected abstract DecodingState init()
                               throws Exception

Invoked to initialize this state machine.

Returns:

the start DecodingState.

Throws:

Exception - if the initialization failed

finishDecode

protected abstract DecodingState finishDecode(List<Object> childProducts,
                                              ProtocolDecoderOutput out)
                                       throws Exception

Called once the state machine has reached its end.

Parameters:

childProducts - contains the messages generated by each of the DecodingStates which were exposed to the received data during the life time of this state machine.

out - the real ProtocolDecoderOutput used by the ProtocolCodecFilter.

Returns:

the next state if the state machine should resume.

Throws:

Exception - if the decoding end failed

destroy

protected abstract void destroy()
                         throws Exception

Invoked to destroy this state machine once the end state has been reached or the session has been closed.

Throws:

Exception - if the destruction failed

decode

public DecodingState decode(IoBuffer in,
                            ProtocolDecoderOutput out)
                     throws Exception

Invoked when data is available for this state.

Specified by:

decode in interface DecodingState

Parameters:

in - the data to be decoded.

out - used to write decoded objects.

Returns:

the next state if a state transition was triggered (use this for loop transitions) or null if the state machine has reached its end.

Throws:

Exception - if the read data violated protocol specification.

finishDecode

public DecodingState finishDecode(ProtocolDecoderOutput out)
                           throws Exception

Invoked when the associated IoSession is closed. This method is useful when you deal with protocols which don't specify the length of a message (e.g. HTTP responses without content-length header). Implement this method to process the remaining data that DecodingState.decode(IoBuffer, ProtocolDecoderOutput) method didn't process completely.

Specified by:

finishDecode in interface DecodingState

Parameters:

out - used to write decoded objects.

Returns:

the next state if a state transition was triggered (use this for loop transitions) or null if the state machine has reached its end.

Throws:

Exception - if the read data violated protocol specification.