step.encoding
Class DeltaIntStrategy

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

Direct Known Subclasses:

PDeltaIntStrategy

public class DeltaIntStrategy

extends RegularValueStrategy

Assume that the next (integer) value is relatively close to the last, and only transmit on the difference from the last value.

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

Credit: A. Samples (Mache)

See Also:

StepInt

Field Summary

static String

STRATEGY_NAME

Fields inherited from class step.encoding.RegularValueStrategy

_nextIsRegular

Fields inherited from class step.encoding.Strategy

_baseEncoder

Constructor Summary

DeltaIntStrategy(Encoder baseEncoder, int threshold)
Create a new "delta" strategy.

Method Summary

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

DeltaIntStrategy

public DeltaIntStrategy(Encoder baseEncoder,
                        int threshold)

Create a new "delta" strategy.

Parameters:

baseEncoder - the encoder to defer to for irregular values

threshold - the maximum (absolute) delta value to encode

Throws:

IllegalArgumentException - if the threshold is < 0.

Method Detail

encode

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

Encode an integer 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

Description copied from class: Encoder

Decode a 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