cgl.narada.service.time.ntptime
Class NTP

java.lang.Object
  cgl.narada.service.time.ntptime.NTP

public class NTP
extends Object

This class implements NTP algorithms described in rfc 1305. Algorithms implemented are combine, filter and select. It also describes static values that can be used or set in the NTP protocol v3 implementation.

Field Summary

static double	FILTER filter weight
static int	FMAX max filter size
static int	HZ clock rate
static int	MAXAGE Max Clock Age
static int	MAXCLOCK Max Select Clocks
static int	MAXDISP Max Dispersion
static int	MAXDISTANCE Max Distance
static int	MAXPOLL Max Polling Interval
static int	MAXSKEW Max Skew error per MAXAGE
static int	MAXSTRATUM Max Stratum
static int	MINCLOCK Min Select Clocks
static double	MINDISP Max Dispersion
static int	MINPOLL Min Polling Interval
static int	NMAX max clocks
static int	PORT NTP Port
static double	SELECT select weight
static int	SHIFT Filter Size
static int	VERSION Version Number
static int	WINDOW Reachability Reg Size

Constructor Summary

NTP()

Method Summary

double	combine(int m) Computes weighted ensemble average.
double	dist(int n) Computes synchronization distance.
void	dts() Computes interval intersection, that is bot and top values.
void	filter(NtpInfo ntpInfo) It filters the NtpInfo object, which contains NTP time information received from a server
double	getTheta() Gets offset
void	initialize() Initializes the vairbales used in this class.
void	select() Selects best subset of clocks in candidate list

Methods inherited from class java.lang.Object

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

Field Detail

VERSION

public static final int VERSION

Version Number

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Constant Field Values

PORT

public static final int PORT

NTP Port

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Constant Field Values

NMAX

public static int NMAX

max clocks

FMAX

public static int FMAX

max filter size

HZ

public static final int HZ

clock rate

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Constant Field Values

MAXSTRATUM

public static final int MAXSTRATUM

Max Stratum

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Constant Field Values

MAXSKEW

public static final int MAXSKEW

Max Skew error per MAXAGE

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Constant Field Values

MAXAGE

public static final int MAXAGE

Max Clock Age

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Constant Field Values

MAXDISTANCE

public static final int MAXDISTANCE

Max Distance

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Constant Field Values

MINPOLL

public static final int MINPOLL

Min Polling Interval

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Constant Field Values

MAXPOLL

public static final int MAXPOLL

Max Polling Interval

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Constant Field Values

MAXDISP

public static final int MAXDISP

Max Dispersion

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Constant Field Values

MINDISP

public static final double MINDISP

Max Dispersion

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Constant Field Values

WINDOW

public static final int WINDOW

Reachability Reg Size

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Constant Field Values

SHIFT

public static final int SHIFT

Filter Size

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Constant Field Values

MINCLOCK

public static final int MINCLOCK

Min Select Clocks

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Constant Field Values

MAXCLOCK

public static final int MAXCLOCK

Max Select Clocks

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Constant Field Values

FILTER

public static final double FILTER

filter weight

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Constant Field Values

SELECT

public static final double SELECT

select weight

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Constant Field Values

Constructor Detail

NTP

public NTP()

Method Detail

getTheta

public double getTheta()

Gets offset

Returns:

double - offset value

combine

public double combine(int m)

Computes weighted ensemble average.

Parameters:

m - int - number of candidates to be weighted

Returns:

double - combined clock offset

dist

public double dist(int n)

Computes synchronization distance.

Parameters:

n - int - peer id

Returns:

double - synchronization distance

dts

public void dts()

Computes interval intersection, that is bot and top values.

filter

public void filter(NtpInfo ntpInfo)

It filters the NtpInfo object, which contains NTP time information received from a server

Parameters:

ntpInfo - NtpInfo - NtpInfo object related to a received NTPDatagramPacket

initialize

public void initialize()

Initializes the vairbales used in this class.

select

public void select()

Selects best subset of clocks in candidate list