org.eclipse.scada.protocol.common.io

Class TimedEndDecoder

java.lang.Object

org.eclipse.scada.protocol.common.io.TimedEndDecoder

All Implemented Interfaces:

org.apache.mina.filter.codec.ProtocolDecoder

Direct Known Subclasses:

ModbusRtuDecoder

public abstract class TimedEndDecoder
extends Object
implements org.apache.mina.filter.codec.ProtocolDecoder

this implements a ProtocolDecoder which detects a frame end based on the absence of new data (timeout).

Some protocol use a timeout to detect a frame end. e.g. Modbus defines a end-of-frame as a timeout of x milliseconds in which no data is sent. This decoder helps to implement such protocols.

In order to use it you will need to derive your class from this one and implement timeout(IoSession, ProtocolDecoderOutput) which will be called in the case of the timeout. The timeout detect will be started by calling tick(IoSession, ProtocolDecoderOutput). It will remember the output and pass it later on to the timeout(IoSession, ProtocolDecoderOutput) call. So when you read data in your ProtocolDecoder#decode(IoSession, org.apache.mina.common.ByteBuffer, ProtocolDecoderOutput) you simply call tick(IoSession, ProtocolDecoderOutput) and the timeout is started or pushed back if it was already started.

If you need to clear the timeout use clear(IoSession)

Author:

Jens Reimann

Field Summary

Fields

Modifier and Type	Field and Description
protected org.apache.mina.core.filterchain.IoFilter.NextFilter	nextFilter

Constructor Summary

Constructors

Constructor and Description
TimedEndDecoder(ScheduledExecutorService scheduler, long timeout, TimeUnit timeUnit) Create a new instance

Method Summary

Modifier and Type	Method and Description
void	clear(org.apache.mina.core.session.IoSession session) Clear the end-of-frame detection for this session
void	dispose(org.apache.mina.core.session.IoSession session)
void	finishDecode(org.apache.mina.core.session.IoSession session, org.apache.mina.filter.codec.ProtocolDecoderOutput out)
void	setNextFilter(org.apache.mina.core.filterchain.IoFilter.NextFilter nextFilter)
protected void	tick()
void	tick(org.apache.mina.core.session.IoSession session, org.apache.mina.filter.codec.ProtocolDecoderOutput out) Start or tick the end-of-frame detection for this session
abstract void	timeout(org.apache.mina.core.session.IoSession session, org.apache.mina.filter.codec.ProtocolDecoderOutput out) Handle the timeout situation

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.mina.filter.codec.ProtocolDecoder

decode

Field Detail

nextFilter

protected org.apache.mina.core.filterchain.IoFilter.NextFilter nextFilter

Constructor Detail

TimedEndDecoder

public TimedEndDecoder(ScheduledExecutorService scheduler,
                       long timeout,
                       TimeUnit timeUnit)

Create a new instance

Parameters:

scheduler - the scheduler to use for cyclic jobs

timeout - the timeout in milliseconds for the end-of-frame detection

Method Detail

tick

protected void tick()

dispose

public void dispose(org.apache.mina.core.session.IoSession session)
             throws Exception

Specified by:

dispose in interface org.apache.mina.filter.codec.ProtocolDecoder

Throws:

Exception

finishDecode

public void finishDecode(org.apache.mina.core.session.IoSession session,
                         org.apache.mina.filter.codec.ProtocolDecoderOutput out)
                  throws Exception

Specified by:

finishDecode in interface org.apache.mina.filter.codec.ProtocolDecoder

Throws:

Exception

timeout

public abstract void timeout(org.apache.mina.core.session.IoSession session,
                             org.apache.mina.filter.codec.ProtocolDecoderOutput out)
                      throws Exception

Handle the timeout situation

Parameters:

session - the session for which the timeout occurred

out - the output

Throws:

Exception

tick

public void tick(org.apache.mina.core.session.IoSession session,
                 org.apache.mina.filter.codec.ProtocolDecoderOutput out)

Start or tick the end-of-frame detection for this session

Parameters:

session - the session

out - the protocol decoder output to use for the finished frame

clear

public void clear(org.apache.mina.core.session.IoSession session)

Clear the end-of-frame detection for this session

Parameters:

session - the session

setNextFilter

public void setNextFilter(org.apache.mina.core.filterchain.IoFilter.NextFilter nextFilter)