examples.ntp

Class SimpleNTPServer

java.lang.Object

examples.ntp.SimpleNTPServer

All Implemented Interfaces:

java.lang.Runnable

public class SimpleNTPServer
extends java.lang.Object
implements java.lang.Runnable

The SimpleNTPServer class is a UDP implementation of a server for the Network Time Protocol (NTP) version 3 as described in RFC 1305. It is a minimal NTP server that doesn't actually adjust the time but only responds to NTP datagram requests with response sent back to originating host with info filled out using the current clock time. To be used for debugging or testing. To prevent this from interfering with the actual NTP service it can be run from any local port.

Field Summary

Fields

Modifier and Type	Field and Description
private int	port
private boolean	running
private java.net.DatagramSocket	socket
private boolean	started

Constructor Summary

Constructors

Constructor and Description
SimpleNTPServer() Create SimpleNTPServer listening on default NTP port.
SimpleNTPServer(int port) Create SimpleNTPServer.

Method Summary

Modifier and Type	Method and Description
void	connect() Connect to server socket and listen for client connections.
int	getPort()
protected void	handlePacket(java.net.DatagramPacket request, long rcvTime) Handle incoming packet.
boolean	isRunning() Return state of whether time service is running.
boolean	isStarted() Return state of whether time service is running.
static void	main(java.lang.String[] args)
void	run() main thread to service client connections.
void	start() Start time service and provide time to client connections.
void	stop() Close server socket and stop listening.

Methods inherited from class java.lang.Object

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

Field Detail

port

private int port

running

private volatile boolean running

started

private boolean started

socket

private java.net.DatagramSocket socket

Constructor Detail

SimpleNTPServer

public SimpleNTPServer()

Create SimpleNTPServer listening on default NTP port.

SimpleNTPServer

public SimpleNTPServer(int port)

Create SimpleNTPServer.

Parameters:

port - the local port the server socket is bound to, or zero for a system selected free port.

Throws:

java.lang.IllegalArgumentException - if port number less than 0

Method Detail

getPort

public int getPort()

isRunning

public boolean isRunning()

Return state of whether time service is running.

Returns:

true if time service is running

isStarted

public boolean isStarted()

Return state of whether time service is running.

Returns:

true if time service is running

connect

public void connect()
             throws java.io.IOException

Connect to server socket and listen for client connections.

Throws:

java.io.IOException - if an I/O error occurs when creating the socket.

start

public void start()
           throws java.io.IOException

Start time service and provide time to client connections.

Throws:

java.io.IOException - if an I/O error occurs when creating the socket.

run

public void run()

main thread to service client connections.

Specified by:

run in interface java.lang.Runnable

handlePacket

protected void handlePacket(java.net.DatagramPacket request,
                            long rcvTime)
                     throws java.io.IOException

Handle incoming packet. If NTP packet is client-mode then respond to that host with a NTP response packet otherwise ignore.

Parameters:

request - incoming DatagramPacket

rcvTime - time packet received

Throws:

java.io.IOException - if an I/O error occurs.

stop

public void stop()

Close server socket and stop listening.

main

public static void main(java.lang.String[] args)