com.sun.sgs.nio.channels
Enum StandardSocketOption

java.lang.Object
  java.lang.Enum<StandardSocketOption>
      com.sun.sgs.nio.channels.StandardSocketOption

All Implemented Interfaces:

SocketOption, Serializable, Comparable<StandardSocketOption>

public enum StandardSocketOption
extends Enum<StandardSocketOption>
implements SocketOption

Defines the standard socket options.

A network channel supports a subset of the socket options defined by this enum and may support additional implementation specific socket options.

Enum Constant Summary

IP_MULTICAST_IF
The network interface for Internet Protocol (IP) multicast datagrams.

IP_MULTICAST_LOOP
Loopback for Internet Protocol (IP) multicast datagrams.

IP_MULTICAST_TTL
The time-to-live for Internet Protocol (IP) multicast datagrams.

IP_TOS
The Type of Service (ToS) octet in the Internet Protocol (IP) header.

SO_BROADCAST
Allow transmission of broadcast datagrams.

SO_KEEPALIVE
Keep connection alive.

SO_LINGER
Linger on close if data is present.

SO_RCVBUF
The size of the socket receive buffer.

SO_REUSEADDR
Re-use address.

SO_SNDBUF
The size of the socket send buffer.

TCP_NODELAY
Disable the Nagle algorithm.

Method Summary

Class<?>	type() Returns the type of the socket option value.
static StandardSocketOption	valueOf(String name) Returns the enum constant of this type with the specified name.
static StandardSocketOption[]	values() Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class java.lang.Enum

clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface com.sun.sgs.nio.channels.SocketOption

name

Enum Constant Detail

SO_BROADCAST

public static final StandardSocketOption SO_BROADCAST

Allow transmission of broadcast datagrams.

The value of this socket option is a Boolean that represents whether the option is enabled or disabled. The option is specific to datagram-oriented channels sending IPv4 datagrams. When the socket option is enabled then the channel can be used to send broadcast datagrams.

The initial value of this socket option is false. The socket option may be enabled or disabled at any time. Some operating systems may require that the Java virtual machine be started with implementation specific privileges to enable this option or send broadcast datagrams.

See Also:

RFC 929: Broadcasting Internet Datagrams

SO_KEEPALIVE

public static final StandardSocketOption SO_KEEPALIVE

Keep connection alive.

The value of this socket option is a Boolean that represents whether the option is enabled or disabled. When the SO_KEEPALIVE option is enabled the operating system may use a keep-alive mechanism to periodically probe the other end of a connection when the connection is otherwise idle. The exact semantics of the keep alive mechanism are implementation specific, as is whether an implementation supports such a mechanism.

The initial value of this socket option is false. The socket option may be enabled or disabled at any time.

See Also:

RFC 1122 Requirements for Internet Hosts -- Communication Layers

SO_SNDBUF

public static final StandardSocketOption SO_SNDBUF

The size of the socket send buffer.

The value of this socket option is an Integer that is the size of the socket send buffer in bytes. The socket send buffer is an output buffer used by the networking implementation. It may need to be increased for high-volume connections. The value of the socket option is a hint to the implementation to size the buffer and the actual size may differ. The socket option can be queried to retrieve the actual size.

For datagram-oriented channels, the size of the send buffer may limit the size of the datagrams sent by the channel. Whether datagrams larger than the buffer size are sent or discarded is implementation specific.

The initial or default size of the socket send buffer is highly implementation specific as is the range of allowable values. Invoking the setOption method to set the socket send buffer to larger than its maximum size causes it to be set to its maximum size. Whether the socket send buffer can be set to a size of zero is implementation specific.

This socket option may be used to change the size prior to connecting or binding the socket. It is implementation specific whther the option can be used to change the size of the socket send buffer after the socket is bound.

SO_RCVBUF

public static final StandardSocketOption SO_RCVBUF

The size of the socket receive buffer.

The value of this socket option is an Integer that is the size of the socket receive buffer in bytes. The socket receive buffer is an input buffer used by the networking implementation. It may need to be increased for high-volume connections or decreased to limit the possible backlog of incoming data. The value of the socket option is a hint to the implementation to size the buffer and the actual size may differ.

For datagram-oriented channels, the size of the receive buffer may limit the size of the datagrams that can be received by the channel. Whether datagrams larger than the buffer size can be received is implementation specific. Increasing the socket receive buffer may be important for cases where datagrams arrive in bursts faster than they can be processed.

In the case of stream-oriented channels and the TCP/IP protocol, the size of the socket receive buffer may be used when advertising the size of the TCP receive window to the remote peer.

The initial or default size of the socket receive buffer is highly implementation specific as is the range of allowable values. Invoking the setOption method to set the socket receive buffer to larger than its maximum size causes it to be set to its maximum size. Whether the socket receive buffer can be set to a size of zero is implementation specific.

This socket option may be used to change the size prior to connecting or binding the socket. It is implementation specific whether the option can be used to change the size of the socket receive buffer after the socket is bound.

See Also:

RFC 1323: TCP Extensions for High Performance

SO_REUSEADDR

public static final StandardSocketOption SO_REUSEADDR

Re-use address.

The value of this socket option is a Boolean that represents whether the option is enabled or disabled. The exact semantics of this socket option are socket type and implementation specific.

In the case of stream-oriented channels, this socket option will usually determine whether the socket can be bind to a socket address when a previous connection involving that socket address is in the TIME_WAIT state. On implementations where the semantics differ, and the socket option is not required to be enabled in order to bind the socket when a previous connection is in this state, then the implementation may choose to ignore this option.

For datagram-oriented sockets the socket option is used to allow multiple programs bind to the same address. This option should be enabled when the channel is to be used for Internet Protocol (IP) multicasting.

The SO_REUSEADDR socket option must be configured prior to connecting or binding the channel's socket. The initial value of this socket option is implementation specific.

See Also:

RFC 793: Transmission Control Protocol

SO_LINGER

public static final StandardSocketOption SO_LINGER

Linger on close if data is present.

The value of this socket option is an Integer that controls the action taken when unsent data is queued on the channel socket and the channel's close method is invoked to close the channel. If the value of the socket option is zero or greater, then it represents a timeout value, in seconds, known as the linger interval. The linger interval is the timeout for the close method to block while the operating system attempts to transmit the unsent data or it decides that it is unable to transmit the data. If the value of the socket option is less than zero then the option is disabled. In that case the close method does not wait until unsent data is transmitted; if possible the operating system will transmit any unsent data before the connection is closed.

This socket option is intended for use with channels that are configured in blocking mode only. The behavior of the close method when this option is enabled on a non-blocking channel is not defined.

The initial value of this socket option is a negative value, meaning that the option is disabled. The option may be enabled, or the linger interval changed, at any time. The maximum value of the linger interval is implementation specific. Invoking the setOption method to set the linger interval to a value that is greater than its maximum value causes the linger interval to be set to its maximum value.

IP_TOS

public static final StandardSocketOption IP_TOS

The Type of Service (ToS) octet in the Internet Protocol (IP) header.

The value of this socket option is an Integer, the least significant 8 bits of which represents the value of the ToS octet in IP packets sent by channels to an IPv4 socket. The interpretation of the ToS octet is network specific and is not defined by this class. Further information on the ToS octet can be found in RFC 1349 and RFC 2474. The value of the socket option that is specified to the setOption method is a hint. An implementation may ignore the value, or ignore specific values.

The initial or default value of the TOS field in the ToS octet is implementation specific but will usually be zero. For datagram-oriented channels the option may be configured at any time after the socket has been bound. The new value of the octet is used when sending subsequent datagrams. It is implementation specific whether this option can be queried or changed prior to binding the socket.

The behavior of this socket option on a stream-oriented channel, or a channel to an IPv6 socket, is not defined in this release.

IP_MULTICAST_IF

public static final StandardSocketOption IP_MULTICAST_IF

The network interface for Internet Protocol (IP) multicast datagrams.

The value of this socket option is a NetworkInterface that represents the outgoing interface for multicast datagrams sent by the datagram-oriented channel. If the channel is to an IPv6 socket then it is implementation specific whether the option also applies to multlicast datagrams sent to IPv4-mapped IPv6 addresses.

The initial value of this socket option is implementation specific and invoking getOption to query this socket option may return null. A value of null implies that the outgoing interface will be selected by the operating system, typically based on the network routing tables.

The network interface for outgoing multicast datagrams can be set after the socket is bound. It is implementation specific whether this option can be queried or changed prior to binding the socket.

See Also:

MulticastChannel

IP_MULTICAST_TTL

public static final StandardSocketOption IP_MULTICAST_TTL

The time-to-live for Internet Protocol (IP) multicast datagrams.

The value of this socket option is an Integer in the range 0 <= value <= 255. It is used to control the scope of multicast datagrams sent by the datagram-oriented channel. In the case of an IPv4 socket the option is the time-to-live (TTL) on multicast datagrams sent by the socket. Datagrams with a TTL of zero are not transmitted on the network but may be delivered locally. In the case of an IPv6 socket the option is the hop limit which is number of hops that the datagram can pass through before expiring on the network.

If the channel is to an IPv6 socket then it is implementation specific whether the option sets the time-to-live on multicast datagrams sent to IPv4-mapped IPv6 addresses.

The initial value of the time-to-live setting is implementation specific but is typically 1. It is also implementation specific whether this option can be queried or changed prior to binding the socket.

See Also:

MulticastChannel

IP_MULTICAST_LOOP

public static final StandardSocketOption IP_MULTICAST_LOOP

Loopback for Internet Protocol (IP) multicast datagrams.

The value of this socket option is a Boolean that controls the loopback of multicast datagrams. The value of the socket option represents if the option is enabled or disabled.

The exact semantics of this socket options are implementation specific. In particular, it is implementation specific whether the socket option applies to multicast datagrams sent from the socket or received by the socket.

If the channel is to an IPv6 socket then it is implementation specific whether the option applies to multicast datagrams sent to IPv4-mapped IPv6 addresses.

The initial value of this socket option is implementation specific but is typically true. It is also implementation specific whether this option can be queried or changed prior to binding the socket.

See Also:

MulticastChannel

TCP_NODELAY

public static final StandardSocketOption TCP_NODELAY

Disable the Nagle algorithm.

The value of this socket option is a Boolean that represents whether the option is enabled or disabled. The socket option is specific to stream-oriented channels using the TCP/IP protocol. TCP/IP uses an algorithm known as The Nagle Algorithm to coalesce short segments and improve network efficiency.

The default value of this socket option is false. The socket option should only be enabled in cases where it is known that the coalescing impacts performance. The socket option may be enabled at any time. In other words, the Nagle Algorithm can be disabled. Once the option is enabled, it is implementation specific whether it can be subsequently disabled. In that case, invoking the setOption method to disable the option has no effect.

See Also:

RFC 1122: Requirements for Internet Hosts -- Communication Layers

Method Detail

values

public static StandardSocketOption[] values()

Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:

for (StandardSocketOption c : StandardSocketOption.values())
    System.out.println(c);

Returns:

an array containing the constants of this enum type, in the order they are declared

valueOf

public static StandardSocketOption valueOf(String name)

Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)

Parameters:

name - the name of the enum constant to be returned.

Returns:

the enum constant with the specified name

Throws:

IllegalArgumentException - if this enum type has no constant with the specified name

NullPointerException - if the argument is null

type

public final Class<?> type()

Returns the type of the socket option value.

Specified by:

type in interface SocketOption

Returns:

the type of the socket option value