SK.gnome.dwarf.tcpip
Class UDPListener

java.lang.Object
  SK.gnome.dwarf.GenericService
      SK.gnome.dwarf.thread.ThreadService
          SK.gnome.dwarf.tcpip.Listener
              SK.gnome.dwarf.tcpip.UDPListener

All Implemented Interfaces:

java.lang.Runnable, Service

Direct Known Subclasses:

MulticastUDPListener

public class UDPListener

extends Listener

Service for receiving client datagrams.

It listenes on a specified port and address and passes the received datagrams to the TCPIPServer for further processing.

Field Summary

protected java.net.InetAddress	connectAddress The internet address to connect to.
protected int	connectPort The network port to connect to.
protected int	packetSize The size of the datagram packet in bytes.
protected java.net.DatagramSocket	socket The datagram socket.

Fields inherited from class SK.gnome.dwarf.tcpip.Listener

address, allowedHosts, deniedHosts, port

Fields inherited from class SK.gnome.dwarf.thread.ThreadService

daemon, thread

Fields inherited from class SK.gnome.dwarf.GenericService

initParameters, parent

Fields inherited from interface SK.gnome.dwarf.Service

INITIALIZED, LOG_DEBUG, LOG_ERROR, LOG_FATAL, LOG_INFO, LOG_TRACE, LOG_WARN, LOG_XFER, SHUTDOWN, STARTED, STOPPED

Constructor Summary

UDPListener(java.lang.String name)
Creates a new UDPListener.

Method Summary

protected boolean	enableThread() Enables or disables the service thread.
protected void	finish() Waits for the thread to complete.
protected java.net.DatagramPacket	getDatagramPacket() Returns the datagram packet.
protected java.net.DatagramSocket	getDatagramSocket() Returns the datagram socket.
void	init(Server parent) Initializes the service.
protected void	loop() Performs the listening operation.
void	setConnectAddress(java.net.InetAddress address) Sets the internet address to connect to.
void	setConnectPort(int port) Sets the port to connect to.
void	setPacketSize(int size) Sets the datagram packet size.

Methods inherited from class SK.gnome.dwarf.tcpip.Listener

acceptHost, setAddress, setAllowedHosts, setDeniedHosts, setPort

Methods inherited from class SK.gnome.dwarf.thread.ThreadService

run, setDaemon, shutdown, start, stop

Methods inherited from class SK.gnome.dwarf.GenericService

getAuthenticator, getAuthFacility, getFullName, getInitParameter, getInitParameterNames, getLogFacility, getLogger, getName, getParameters, getPrincipal, getShutdownTimeout, getState, log, log, login, logout, setAuthFacility, setInitParameters, setLogFacility, toString

Methods inherited from class java.lang.Object

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

Field Detail

connectAddress

protected java.net.InetAddress connectAddress

The internet address to connect to.

See Also:

setConnectAddress(InetAddress)

connectPort

protected int connectPort

The network port to connect to.

See Also:

setConnectPort(int)

packetSize

protected int packetSize

The size of the datagram packet in bytes.

Default value: TCPIPConstants.TCPIP_DEFAULT_UDP_PACKET_SIZE

See Also:

setPacketSize(int)

socket

protected java.net.DatagramSocket socket

The datagram socket.

See Also:

init(Server)

Constructor Detail

UDPListener

public UDPListener(java.lang.String name)

Creates a new UDPListener.

Method Detail

setConnectAddress

public void setConnectAddress(java.net.InetAddress address)

Sets the internet address to connect to.

Parameters:

address - the internet address

See Also:

Listener.address

setConnectPort

public void setConnectPort(int port)

Sets the port to connect to.

Parameters:

port - the port

See Also:

Listener.port

setPacketSize

public void setPacketSize(int size)

Sets the datagram packet size.

Parameters:

size - the packet size in bytes

Throws:

java.lang.IllegalArgumentException - if the size exceeds the TCPIPConstants.TCPIP_MAX_UDP_PACKET_SIZE limit

See Also:

packetSize

init

public void init(Server parent)
          throws ServiceException

Initializes the service.

Sets the socket field to value returned by the getDatagramSocket() method.

This method requires that the parent server is an instance of the TCPIPServer class.

Specified by:

init in interface Service

Overrides:

init in class GenericService

Throws:

ServiceException

finish

protected void finish()

Waits for the thread to complete.

It closes the socket, which causes an interruption of the blocked listening thread, so it can finish gracefully.

Overrides:

finish in class ThreadService

enableThread

protected boolean enableThread()

Enables or disables the service thread.

This method always returns true, so the new listening thread is always started.

Overrides:

enableThread in class ThreadService

Returns:

true if the thread is enabled

loop

protected void loop()

Performs the listening operation.

Listenes on a specified port and address via the socket. The datagram packet for receiving client data is obtained from the getDatagramPacket() method. If a new client datagram is detected, the listener first checks whether the datagram should be accepted by invoking the inherited Listener.acceptHost(InetAddress) method with the address of the received datagram. If the result is true, it passes the datagram to the parent server by calling its TCPIPServer.enqueue(Object) method. In the case the listener will not accept the datagram, it is discarded and a warning message is written to the log.

Overrides:

loop in class ThreadService

getDatagramSocket

protected java.net.DatagramSocket getDatagramSocket()
                                             throws ServiceException

Returns the datagram socket.

Returns the socket for listening. The returned socket will be bound to the Listener.port. If the Listener.address field is null, the socket will use all available addresses. If the connectAddress and connectPort is not null, the socket will be connected to the given address and port before returned from this method.

Throws:

ServiceException

getDatagramPacket

protected java.net.DatagramPacket getDatagramPacket()

Returns the datagram packet.

Returns the datagram packet for receiving client data. The packet size must not exceed the TCPIPConstants.TCPIP_MAX_UDP_PACKET_SIZE limit. This method returns a new java.net.DatagramPacket object with size equal to the packetSize. It can be overriden to implement the packet caching/reusing for a high-performance streaming servers, for example.