step.encoding
Class WindowIntStrategy

java.lang.Object
  |
  +--step.encoding.Encoder
        |
        +--step.encoding.Strategy
              |
              +--step.encoding.RegularValueStrategy
                    |
                    +--step.encoding.WindowIntStrategy

Direct Known Subclasses:

PWindowIntStrategy

public class WindowIntStrategy

extends RegularValueStrategy

Assume (integer) values are in the neighborhood of a base value, and transmit the offset from the base. Irregular values shift the base of computation.

NOTE: Although values may be more than 4 bytes (i.e. long), their difference must be in the int range. Otherwise, the behavior of this encoder is undefined.

Algorithm:

 delta := current - base
 if |delta| <= threshold
     then -> delta
     else -> meta:IrregularValueEvent, base:=current
 

See Also:

StepInt, OffsetIntStrategy

Field Summary

static String

STRATEGY_NAME

Fields inherited from class step.encoding.RegularValueStrategy

_nextIsRegular

Fields inherited from class step.encoding.Strategy

_baseEncoder

Constructor Summary

WindowIntStrategy(Encoder baseEncoder, int threshold)
Create a new "window" strategy.

Method Summary

StepObject	decode(DecodeContext context) Decode a window value.
void	dump(int level)
void	encode(StepObject o, EncodeContext context) Encode a window value.

Methods inherited from class step.encoding.RegularValueStrategy

setNextIsRegular

Methods inherited from class step.encoding.Strategy

baseDecode, baseEncode, eventMessage

Methods inherited from class step.encoding.Encoder

getFactory, getName, indent, makeFieldName

Methods inherited from class java.lang.Object

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

Field Detail

STRATEGY_NAME

public static final String STRATEGY_NAME

See Also:

Constant Field Values

Constructor Detail

WindowIntStrategy

public WindowIntStrategy(Encoder baseEncoder,
                         int threshold)

Create a new "window" strategy.

Parameters:

baseEncoder - the encoder to use for deviant values.

threshold - the maximum (absolute) difference from the current base to allow.

Throws:

IllegalArgumentException - if the threshold is not >= 0.

Method Detail

encode

public void encode(StepObject o,
                   EncodeContext context)
            throws EncoderException,
                   IOException

Encode a window value.

Specified by:

encode in class Encoder

Throws:

EncoderException - if the value is not a StepInt.

IOException - if the encode operation encountered an I/O failure.

decode

public StepObject decode(DecodeContext context)
                  throws EncoderException,
                         IOException

Decode a window value.

Specified by:

decode in class Encoder

Throws:

IOException - if the decode operation encountered an I/O failure.

EncoderException - if the decode operation encountered an error.

dump

public void dump(int level)

Specified by:

dump in class Encoder