Module jdk.net

Package jdk.net

Class ExtendedSocketOptions

java.lang.Object

jdk.net.ExtendedSocketOptions

public final class ExtendedSocketOptions
extends Object

Defines extended socket options, beyond those defined in StandardSocketOptions. These options may be platform specific.

Since:

1.8

Field Summary

Fields

Modifier and Type	Field	Description
static final SocketOption<Boolean>	IP_DONTFRAGMENT	Disable IP packet fragmentation.
static final SocketOption<Integer>	SO_INCOMING_NAPI_ID	Identifies the receive queue that the last incoming packet for the socket was received on.
static final SocketOption<UnixDomainPrincipal>	SO_PEERCRED	Unix Domain peer credentials.
static final SocketOption<Integer>	TCP_KEEPCOUNT	Keep-Alive retransmission maximum limit.
static final SocketOption<Integer>	TCP_KEEPIDLE	Keep-Alive idle time.
static final SocketOption<Integer>	TCP_KEEPINTERVAL	Keep-Alive retransmission interval time.
static final SocketOption<Boolean>	TCP_QUICKACK	Disable Delayed Acknowledgements.

Method Summary

Methods declared in class java.lang.Object

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

Field Details

TCP_QUICKACK

public static final SocketOption<Boolean> TCP_QUICKACK

Disable Delayed Acknowledgements.

This socket option can be used to reduce or disable delayed acknowledgments (ACKs). When TCP_QUICKACK is enabled, ACKs are sent immediately, rather than delayed if needed in accordance to normal TCP operation. This option is not permanent, it only enables a switch to or from TCP_QUICKACK mode. Subsequent operations of the TCP protocol will once again disable/enable TCP_QUICKACK mode depending on internal protocol processing and factors such as delayed ACK timeouts occurring and data transfer, therefore this option needs to be set with setOption after each operation of TCP on a given socket.

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. The exact semantics of this socket option are socket type and system dependent.

Since:

10

TCP_KEEPIDLE

public static final SocketOption<Integer> TCP_KEEPIDLE

Keep-Alive idle time.

The value of this socket option is an Integer that is the number of seconds of idle time before keep-alive initiates a probe. The socket option is specific to stream-oriented sockets using the TCP/IP protocol. The exact semantics of this socket option are system dependent.

When the SO_KEEPALIVE option is enabled, TCP probes a connection that has been idle for some amount of time. The default value for this idle period is system dependent, but is typically 2 hours. The TCP_KEEPIDLE option can be used to affect this value for a given socket.

Since:

11

TCP_KEEPINTERVAL

public static final SocketOption<Integer> TCP_KEEPINTERVAL

Keep-Alive retransmission interval time.

The value of this socket option is an Integer that is the number of seconds to wait before retransmitting a keep-alive probe. The socket option is specific to stream-oriented sockets using the TCP/IP protocol. The exact semantics of this socket option are system dependent.

When the SO_KEEPALIVE option is enabled, TCP probes a connection that has been idle for some amount of time. If the remote system does not respond to a keep-alive probe, TCP retransmits the probe after some amount of time. The default value for this retransmission interval is system dependent, but is typically 75 seconds. The TCP_KEEPINTERVAL option can be used to affect this value for a given socket.

Since:

11

TCP_KEEPCOUNT

public static final SocketOption<Integer> TCP_KEEPCOUNT

Keep-Alive retransmission maximum limit.

The value of this socket option is an Integer that is the maximum number of keep-alive probes to be sent. The socket option is specific to stream-oriented sockets using the TCP/IP protocol. The exact semantics of this socket option are system dependent.

When the SO_KEEPALIVE option is enabled, TCP probes a connection that has been idle for some amount of time. If the remote system does not respond to a keep-alive probe, TCP retransmits the probe a certain number of times before a connection is considered to be broken. The default value for this keep-alive probe retransmit limit is system dependent, but is typically 8. The TCP_KEEPCOUNT option can be used to affect this value for a given socket.

Since:

11

SO_INCOMING_NAPI_ID

public static final SocketOption<Integer> SO_INCOMING_NAPI_ID

Identifies the receive queue that the last incoming packet for the socket was received on.

The value of this socket option is a positive Integer that identifies a receive queue that the application can use to split the incoming flows among threads based on the queue identifier. The value is 0 when the socket is not bound, a packet has not been received, or more generally, when there is no receive queue to identify. The socket option is supported by both stream-oriented and datagram-oriented sockets.

The socket option is read-only and an attempt to set the socket option will throw SocketException.

API Note:

Network devices may have multiple queues or channels to transmit and receive network packets. The SO_INCOMING_NAPI_ID socket option provides a hint to the application to indicate the receive queue on which an incoming socket connection or packets for that connection are directed to. An application may take advantage of this by handling all socket connections assigned to a specific queue on one thread.

Since:

15

SO_PEERCRED

public static final SocketOption<UnixDomainPrincipal> SO_PEERCRED

Unix Domain peer credentials.

The value of this socket option is a UnixDomainPrincipal that represents the credentials of a peer connected to a Unix Domain socket. The credentials are those that applied at the time the socket was first connected or accepted.

The socket option is read-only and an attempt to set the socket option will throw SocketException. SocketException is also thrown when attempting to get the value of the socket option on an unconnected Unix Domain socket.

Since:

16

IP_DONTFRAGMENT

public static final SocketOption<Boolean> IP_DONTFRAGMENT

Disable IP packet fragmentation.

The value of this socket option is a Boolean that represents whether the option is enabled or disabled. When true fragmentation of outgoing IPv4 and IPv6 packets does not occur. This option can only be used with datagram sockets. When set, care must be taken to limit outgoing packet sizes to the local MTU. Depending on the implementation and the network interface, packets larger than the MTU may be sent or dropped silently or dropped with an exception thrown. For IPv6 sockets it is system dependent whether the option also applies to datagrams sent to IPv4 addresses.

API Note:

For IPv4 this option sets the DF (Do not Fragment) flag in the IP packet header. This instructs intermediate routers to not fragment the packet. IPv6 routers never fragment packets. Instead, fragmentation is handled by the sending and receiving nodes exclusively. Setting this option for an IPv6 socket ensures that packets to be sent are never fragmented, in which case, the local network MTU must be observed.