p2ps.imp.net
Interface ServerSocket

All Known Implementing Classes:

InetServerSocket

public interface ServerSocket

An interface to an underlying server socket. This interface has many of the same methods as java.net.ServerSocket, but allows different server socket implementations to be plugged in.

Version:

$Revision: 295 $

Author:

Ian Wang

Method Summary

Socket	accept() Listens for a connection to be made to this socket and accepts it.
void	bind(java.net.SocketAddress endpoint) Binds the ServerSocket to a specific address (IP address and port number).
void	bind(java.net.SocketAddress endpoint, int backlog) Binds the ServerSocket to a specific address (IP address and port number).
void	close() Closes this socket.
int	getLocalPort() Returns the port on which this socket is listening.
java.net.SocketAddress	getLocalSocketAddress() Returns the address of the endpoint this socket is bound to, or null if it is not bound yet.
int	getReceiveBufferSize() Gets the value of the SO_RCVBUF option for this ServerSocket, that is the proposed buffer size that will be used for Sockets accepted from this ServerSocket.
boolean	getReuseAddress() Tests if SO_REUSEADDR is enabled.
int	getSoTimeout() Retrive setting for SO_TIMEOUT.
boolean	isBound() Returns the binding state of the ServerSocket.
boolean	isClosed() Returns the closed state of the ServerSocket.
void	setReceiveBufferSize(int size) Sets a default proposed value for the SO_RCVBUF option for sockets accepted from this ServerSocket.
void	setReuseAddress(boolean on) Enable/disable the SO_REUSEADDR socket option.
void	setSoTimeout(int timeout) Enable/disable SO_TIMEOUT with the specified timeout, in milliseconds.

Method Detail

bind

public void bind(java.net.SocketAddress endpoint)
          throws java.io.IOException

Binds the ServerSocket to a specific address (IP address and port number).

If the address is null, then the system will pick up an ephemeral port and a valid local address to bind the socket.

Parameters:

endpoint - The IP address & port number to bind to.

Throws:

java.lang.IllegalArgumentException - if endpoint is a SocketAddress subclass not supported by this socket

java.io.IOException - if the bind operation fails, or if the socket is already bound.

java.lang.SecurityException - if a SecurityManager is present and its checkListen method doesn't allow the operation.

Since:

1.4

bind

public void bind(java.net.SocketAddress endpoint,
                 int backlog)
          throws java.io.IOException

Binds the ServerSocket to a specific address (IP address and port number).

If the address is null, then the system will pick up an ephemeral port and a valid local address to bind the socket.

The backlog argument must be a positive value greater than 0. If the value passed if equal or less than 0, then the default value will be assumed.

Parameters:

endpoint - The IP address & port number to bind to.

backlog - The listen backlog length.

Throws:

java.lang.IllegalArgumentException - if endpoint is a SocketAddress subclass not supported by this socket

java.io.IOException - if the bind operation fails, or if the socket is already bound.

java.lang.SecurityException - if a SecurityManager is present and its checkListen method doesn't allow the operation.

Since:

1.4

isBound

public boolean isBound()

Returns the binding state of the ServerSocket.

Returns:

true if the ServerSocket succesfuly bound to an address

Since:

1.4

accept

public Socket accept()
              throws java.io.IOException

Listens for a connection to be made to this socket and accepts it. The method blocks until a connection is made.

A new Socket s is created and, if there is a security manager, the security manager's checkAccept method is called with s.getInetAddress().getHostAddress() and s.getPort() as its arguments to ensure the operation is allowed. This could result in a SecurityException.

Returns:

the new Socket

Throws:

java.io.IOException - if an I/O error occurs when waiting for a connection.

java.lang.SecurityException - if a security manager exists and its checkListen method doesn't allow the operation.

java.net.SocketTimeoutException - if a timeout was previously set with setSoTimeout and the timeout has been reached.

java.nio.channels.IllegalBlockingModeException - if this socket has an associated channel, the channel is in non-blocking mode, and there is no connection ready to be accepted

See Also:

SecurityManager.checkAccept(java.lang.String, int)

close

public void close()
           throws java.io.IOException

Closes this socket.

Any thread currently blocked in accept() will throw a SocketException.

If this socket has an associated channel then the channel is closed as well.

Throws:

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

isClosed

public boolean isClosed()

Returns the closed state of the ServerSocket.

Returns:

true if the socket has been closed

Since:

1.4

getLocalPort

public int getLocalPort()

Returns the port on which this socket is listening.

Returns:

the port number to which this socket is listening or -1 if the socket is not bound yet.

getLocalSocketAddress

public java.net.SocketAddress getLocalSocketAddress()

Returns the address of the endpoint this socket is bound to, or null if it is not bound yet.

Returns:

a SocketAddress representing the local endpoint of this socket, or null if it is not bound yet.

Since:

1.4

See Also:

getLocalPort(), bind(java.net.SocketAddress)

getSoTimeout

public int getSoTimeout()
                 throws java.io.IOException

Retrive setting for SO_TIMEOUT. 0 returns implies that the option is disabled (i.e., timeout of infinity).

Returns:

the SO_TIMEOUT value

Throws:

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

Since:

JDK1.1

See Also:

setSoTimeout(int)

setSoTimeout

public void setSoTimeout(int timeout)
                  throws java.net.SocketException

Enable/disable SO_TIMEOUT with the specified timeout, in milliseconds. With this option set to a non-zero timeout, a call to accept() for this ServerSocket will block for only this amount of time. If the timeout expires, a java.net.SocketTimeoutException is raised, though the ServerSocket is still valid. The option must be enabled prior to entering the blocking operation to have effect. The timeout must be > 0. A timeout of zero is interpreted as an infinite timeout.

Parameters:

timeout - the specified timeout, in milliseconds

Throws:

java.net.SocketException - if there is an error in the underlying protocol, such as a TCP error.

Since:

JDK1.1

See Also:

getSoTimeout()

getReuseAddress

public boolean getReuseAddress()
                        throws java.net.SocketException

Tests if SO_REUSEADDR is enabled.

Returns:

a boolean indicating whether or not SO_REUSEADDR is enabled.

Throws:

java.net.SocketException - if there is an error in the underlying protocol, such as a TCP error.

Since:

1.4

See Also:

setReuseAddress(boolean)

setReuseAddress

public void setReuseAddress(boolean on)
                     throws java.net.SocketException

Enable/disable the SO_REUSEADDR socket option.

When a TCP connection is closed the connection may remain in a timeout state for a period of time after the connection is closed (typically known as the TIME_WAIT state or 2MSL wait state). For applications using a well known socket address or port it may not be possible to bind a socket to the required SocketAddress if there is a connection in the timeout state involving the socket address or port.

Enabling SO_REUSEADDR prior to binding the socket using bind(java.net.SocketAddress) allows the socket to be bound even though a previous connection is in a timeout state.

When a ServerSocket is created the initial setting of SO_REUSEADDR is not defined. Applications can use getReuseAddress() to determine the initial setting of SO_REUSEADDR.

The behaviour when SO_REUSEADDR is enabled or disabled after a socket is bound (See isBound()) is not defined.

Parameters:

on - whether to enable or disable the socket option

Throws:

java.net.SocketException - if an error occurs enabling or disabling the SO_RESUEADDR socket option, or the socket is closed.

Since:

1.4

See Also:

getReuseAddress(), bind(java.net.SocketAddress), isBound(), isClosed()

getReceiveBufferSize

public int getReceiveBufferSize()
                         throws java.net.SocketException

Gets the value of the SO_RCVBUF option for this ServerSocket, that is the proposed buffer size that will be used for Sockets accepted from this ServerSocket.

Note, the value actually set in the accepted socket is determined by calling Socket.getReceiveBufferSize().

Returns:

the value of the SO_RCVBUF option for this Socket.

Throws:

java.net.SocketException - if there is an error in the underlying protocol, such as a TCP error.

Since:

1.4

See Also:

setReceiveBufferSize(int)

setReceiveBufferSize

public void setReceiveBufferSize(int size)
                          throws java.net.SocketException

Sets a default proposed value for the SO_RCVBUF option for sockets accepted from this ServerSocket. The value actually set in the accepted socket must be determined by calling Socket.getReceiveBufferSize() after the socket is returned by accept().

The value of SO_RCVBUF is used both to set the size of the internal socket receive buffer, and to set the size of the TCP receive window that is advertized to the remote peer.

It is possible to change the value subsequently, by calling Socket.setReceiveBufferSize(int). However, if the application wishes to allow a receive window larger than 64K bytes, as defined by RFC1323 then the proposed value must be set in the ServerSocket before it is bound to a local address. This implies, that the ServerSocket must be created with the no-argument constructor, then setReceiveBufferSize() must be called and lastly the ServerSocket is bound to an address by calling bind().

Failure to do this will not cause an error, and the buffer size may be set to the requested value but the TCP receive window in sockets accepted from this ServerSocket will be no larger than 64K bytes.

Parameters:

size - the size to which to set the receive buffer size. This value must be greater than 0.

Throws:

java.net.SocketException - if there is an error in the underlying protocol, such as a TCP error.

java.lang.IllegalArgumentException - if the value is 0 or is negative.

Since:

1.4

See Also:

getReceiveBufferSize()