Defines the standard socket options.
The name
of each socket option defined by this
class is its field name.
In this release, the socket options defined here are used by network
channels in the channels
package.
Field Summary
public static final SocketOption<NetworkInterface> | IP_MULTICAST_IF | The network interface for Internet Protocol (IP) multicast datagrams. |
public static final SocketOption<Boolean> | IP_MULTICAST_LOOP | Loopback for Internet Protocol (IP) multicast datagrams. |
public static final SocketOption<Integer> | IP_MULTICAST_TTL | The time-to-live for Internet Protocol (IP) multicast datagrams. |
public static final SocketOption<Integer> | IP_TOS | The Type of Service (ToS) octet in the Internet Protocol (IP) header. |
public static final SocketOption<Boolean> | SO_BROADCAST | Allow transmission of broadcast datagrams. |
public static final SocketOption<Boolean> | SO_KEEPALIVE | Keep connection alive. |
public static final SocketOption<Integer> | SO_LINGER | Linger on close if data is present. |
public static final SocketOption<Integer> | SO_RCVBUF | The size of the socket receive buffer. |
public static final SocketOption<Boolean> | SO_REUSEADDR | Re-use address. |
public static final SocketOption<Integer> | SO_SNDBUF | The size of the socket send buffer. |
public static final SocketOption<Boolean> | TCP_NODELAY | Disable the Nagle algorithm. |
Inherited Method Summary
Fields
public static final SocketOption<NetworkInterface> 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 socket. For IPv6
sockets then it is system dependent whether setting this option also
sets the outgoing interface for multicast datagrams sent to IPv4
addresses.
The initial/default value of this socket option may be null
to indicate that outgoing interface will be selected by the operating
system, typically based on the network routing tables. An implementation
allows this socket option to be set after the socket is bound. Whether
the socket option can be queried or changed prior to binding the socket
is system dependent.
public static final SocketOption<Boolean> 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 system dependent.
In particular, it is system dependent whether the loopback applies to
multicast datagrams sent from the socket or received by the socket.
For IPv6
sockets then it is
system dependent whether the option also applies to multicast datagrams
sent to IPv4 addresses.
The initial/default value of this socket option is TRUE
. An
implementation allows this socket option to be set after the socket is
bound. Whether the socket option can be queried or changed prior to
binding the socket is system dependent.
public static final SocketOption<Integer> 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 socket.
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. For IPv6 sockets it is
system dependent whether the option also sets the time-to-live
on multicast datagrams sent to IPv4 addresses.
The initial/default value of the time-to-live setting is typically
1
. An implementation allows this socket option to be set after
the socket is bound. Whether the socket option can be queried or changed
prior to binding the socket is system dependent.
public static final SocketOption<Integer> IP_TOS
The Type of Service (ToS) octet in the Internet Protocol (IP) header.
The value of this socket option is an Integer
representing
the value of the ToS octet in IP packets sent by sockets 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 is a hint. An implementation may ignore the
value, or ignore specific values.
The initial/default value of the TOS field in the ToS octet is
implementation specific but will typically be 0
. For
datagram-oriented sockets 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 system dependent whether this option can be
queried or changed prior to binding the socket.
The behavior of this socket option on a stream-oriented socket, or an
IPv6
socket, is not defined in this
release.
See Also
public static final SocketOption<Boolean> 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 sockets sending to IPv4
broadcast addresses. When the socket option is enabled then the socket
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.
public static final SocketOption<Boolean> 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 is system dependent and therefore unspecified.
The initial value of this socket option is FALSE
. The socket
option may be enabled or disabled at any time.
public static final SocketOption<Integer> 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 socket and a method
to close the socket is invoked. 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 sockets that are configured
in blocking
mode
only. The behavior of the close
method when this option is
enabled on a non-blocking socket 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 system dependent. Setting the linger interval to a value that is greater than its maximum value causes the linger interval to be set to its maximum value.
See Also
public static final SocketOption<Integer> 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 sockets, the size of the receive buffer may limit the size of the datagrams that can be received. Whether datagrams larger than the buffer size can be received is system dependent. 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 sockets 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/default size of the socket receive buffer and the range of allowable values is system dependent although a negative size is not allowed. An attempt to set the socket receive buffer to larger than its maximum size causes it to be set to its maximum size.
An implementation allows this socket option to be set before the socket is bound or connected. Whether an implementation allows the socket receive buffer to be changed after the socket is bound is system dependent.
public static final SocketOption<Boolean> 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 system dependent.
In the case of stream-oriented sockets, this socket option will usually determine whether the socket can be bound 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 socket is to be used for Internet Protocol (IP) multicasting.
An implementation allows this socket option to be set before the socket is bound or connected. Changing the value of this socket option after the socket is bound has no effect. The default value of this socket option is system dependent.
public static final SocketOption<Integer> 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 sockets, the size of the send buffer may limit the size of the datagrams that may be sent by the socket. Whether datagrams larger than the buffer size are sent or discarded is system dependent.
The initial/default size of the socket send buffer and the range of allowable values is system dependent although a negative size is not allowed. An attempt to set the socket send buffer to larger than its maximum size causes it to be set to its maximum size.
An implementation allows this socket option to be set before the socket is bound or connected. Whether an implementation allows the socket send buffer to be changed after the socket is bound is system dependent.
See Also
public static final SocketOption<Boolean> 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 sockets 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 system dependent whether it can be subsequently
disabled. If it cannot, then invoking the setOption
method to
disable the option has no effect.