java.net.SocketOptions Maven / Gradle / Ivy

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This work corresponds to the API signatures of JSR 219: Foundation Profile 1.1. In the event of a discrepency between this work and the JSR 219 specification, which is available at http://www.jcp.org/en/jsr/detail?id=219, the latter takes precedence. */ package java.net; /** * Interface of methods to get/set socket options. This interface is * implemented by: SocketImpl and DatagramSocketImpl. * NOTE: java.net.SocketImpl is found in J2ME CDC profiles such as * J2ME Foundation Profile. * Subclasses of these should override the methods * of this interface in order to support their own options. *

* The methods and constants which specify options in this interface are * for implementation only. If you're not subclassing SocketImpl or * DatagramSocketImpl, you won't use these directly. There are * type-safe methods to get/set each of these options in Socket, ServerSocket, * DatagramSocket and MulticastSocket. * NOTE: java.net.SocketImpl, java.net.Socket, java.net.ServerSocket, * java.net.MulticastSocket are found in J2ME CDC profiles such as * J2ME Foundation Profile. *

* @version 1.30, 03/12/05 * @author David Brown */ public interface SocketOptions { /** * Disable Nagle's algorithm for this connection. Written data * to the network is not buffered pending acknowledgement of * previously written data. *

* Valid for TCP only: SocketImpl. * NOTE: java.net.SocketImpl is found in J2ME CDC profiles such as * J2ME Foundation Profile. *

* @see Socket#setTcpNoDelay * @see Socket#getTcpNoDelay */ public static final int TCP_NODELAY = 1; /** * Fetch the local address binding of a socket (this option cannot * be "set" only "gotten", since sockets are bound at creation time, * and so the locally bound address cannot be changed). The default local * address of a socket is INADDR_ANY, meaning any local address on a * multi-homed host. A multi-homed host can use this option to accept * connections to only one of its addresses (in the case of a * ServerSocket or DatagramSocket), or to specify its return address * to the peer (for a Socket or DatagramSocket). The parameter of * this option is an InetAddress. *

* This option must be specified in the constructor. *

* Valid for: SocketImpl, DatagramSocketImpl *

* NOTE: java.net.Socket, java.net.ServerSocket, java.net.SocketImpl * are found in J2ME CDC profiles such as J2ME Foundation Profile. *

* @see Socket#getLocalAddress * @see DatagramSocket#getLocalAddress */ public static final int SO_BINDADDR = 15; /** *Sets SO_REUSEADDR for a socket. This is used only for MulticastSockets * in java, and it is set by default for MulticastSockets. *

* Valid for: DatagramSocketImpl */ public static final int SO_REUSEADDR = 4; /** * Sets SO_BROADCAST for a socket. This option enables and disables * the ability of the process to send broadcast messages. It is supported * for only datagram sockets and only on networks that support * the concept of a broadcast message (e.g. Ethernet, token ring, etc.), * and it is set by default for DatagramSockets. * @since 1.4 */ public static final int SO_BROADCAST = 32; /** *Set which outgoing interface on which to send multicast packets. * Useful on hosts with multiple network interfaces, where applications * want to use other than the system default. Takes/returns an InetAddress. *

* Valid for Multicast: DatagramSocketImpl *

* @see MulticastSocket#setInterface(InetAddress) * @see MulitcastSocket#getInterface() */ public static final int IP_MULTICAST_IF = 16; /** *Same as above. This option is introduced so that the behaviour * with IP_MULTICAST_IF will be kept the same as before, while * this new option can support setting outgoing interfaces with either * IPv4 and IPv6 addresses. * * NOTE: make sure there is no conflict with this * @see MulticastSocket#setNetworkInterface(NetworkInterface) * @see MulticastSocket#getNetworkInterface() * @since 1.4 */ public static final int IP_MULTICAST_IF2 = 31; /** * This option enables or disables local loopback of multicast datagrams. * This option is enabled by default for Multicast Sockets. * @since 1.4 */ public static final int IP_MULTICAST_LOOP = 18; /** * This option sets the type-of-service or traffic class field * in the IP header for a TCP or UDP socket. * @since 1.4 */ public static final int IP_TOS = 3; /** * Specify a linger-on-close timeout. This option disables/enables * immediate return from a close() of a TCP Socket. Enabling * this option with a non-zero Integer timeout means that a * close() will block pending the transmission and acknowledgement * of all data written to the peer, at which point the socket is closed * gracefully. Upon reaching the linger timeout, the socket is * closed forcefully, with a TCP RST. Enabling the option with a * timeout of zero does a forceful close immediately. If the specified * timeout value exceeds 65,535 it will be reduced to 65,535. *

* Valid only for TCP: SocketImpl * NOTE: java.net.SocketImpl is found in J2ME CDC profiles such as * J2ME Foundation Profile. * * @see Socket#setSoLinger * @see Socket#getSoLinger */ public static final int SO_LINGER = 128; /** *Set a timeout on blocking Socket operations: *

     * ServerSocket.accept();
     * SocketInputStream.read();
     * DatagramSocket.receive();
     * 

The option must be set prior to entering a blocking * operation to take effect. If the timeout expires and the * operation would continue to block, * java.io.InterruptedIOException is raised. The Socket is * not closed in this case. * *

Valid for all sockets: SocketImpl, DatagramSocketImpl * NOTE: java.net.SocketImpl is found in J2ME CDC profiles such as * J2ME Foundation Profile. * * @see Socket#setSoTimeout * @see ServerSocket#setSoTimeout * @see DatagramSocket#setSoTimeout */ public static final int SO_TIMEOUT = 4102; /** * Set a hint the size of the underlying buffers used by the * platform for outgoing network I/O. When used in set, this is a * suggestion to the kernel from the application about the size of * buffers to use for the data to be sent over the socket. When * used in get, this must return the size of the buffer actually * used by the platform when sending out data on this socket. * * Valid for all sockets: SocketImpl, DatagramSocketImpl * NOTE: java.net.SocketImpl is found in J2ME CDC profiles such as * J2ME Foundation Profile. * * @see Socket#setSendBufferSize * @see Socket#getSendBufferSize * @see DatagramSocket#setSendBufferSize * @see DatagramSocket#getSendBufferSize */ public static final int SO_SNDBUF = 4097; /** * Set a hint the size of the underlying buffers used by the * platform for incoming network I/O. When used in set, this is a * suggestion to the kernel from the application about the size of * buffers to use for the data to be received over the * socket. When used in get, this must return the size of the * buffer actually used by the platform when receiving in data on * this socket. * * Valid for all sockets: SocketImpl, DatagramSocketImpl * NOTE: java.net.SocketImpl is found in J2ME CDC profiles such as * J2ME Foundation Profile. * * @see Socket#setReceiveBufferSize * @see Socket#getReceiveBufferSize * @see DatagramSocket#setReceiveBufferSize * @see DatagramSocket#getReceiveBufferSize */ public static final int SO_RCVBUF = 4098; /** * When the keepalive option is set for a TCP socket and no data * has been exchanged across the socket in either direction for * 2 hours (NOTE: the actual value is implementation dependent), * TCP automatically sends a keepalive probe to the peer. This probe is a * TCP segment to which the peer must respond. * One of three responses is expected: * 1. The peer responds with the expected ACK. The application is not * notified (since everything is OK). TCP will send another probe * following another 2 hours of inactivity. * 2. The peer responds with an RST, which tells the local TCP that * the peer host has crashed and rebooted. The socket is closed. * 3. There is no response from the peer. The socket is closed. * * The purpose of this option is to detect if the peer host crashes. * * Valid only for TCP socket: SocketImpl * NOTE: java.net.SocketImpl is found in J2ME CDC profiles such as * J2ME Foundation Profile. * * @see Socket#setKeepAlive * @see Socket#getKeepAlive */ public static final int SO_KEEPALIVE = 8; /** * When the OOBINLINE option is set, any TCP urgent data received on * the socket will be received through the socket input stream. * When the option is disabled (which is the default) urgent data * is silently discarded. * * @see Socket#setOOBInline * @see Socket#getOOBInline */ public static final int SO_OOBINLINE = 4099; /** * Enable/disable the option specified by optID. If the option * is to be enabled, and it takes an option-specific "value", this is * passed in value. The actual type of value is option-specific, * and it is an error to pass something that isn't of the expected type: *

     * SocketImpl s;
     * ...
     * s.setOption(SO_LINGER, new Integer(10));
     *    // OK - set SO_LINGER w/ timeout of 10 sec.
     * s.setOption(SO_LINGER, new Double(10));
     *    // ERROR - expects java.lang.Integer
     *

     * s.setOption(TCP_NODELAY, new Boolean(true));
     *    // OK - enables TCP_NODELAY, a binary option
     * 

     * s.setOption(TCP_NODELAY, new Boolean(false));
     *    // OK - disables TCP_NODELAY
     * s.setOption(SO_LINGER, new Boolean(false));
     *    // OK - disables SO_LINGER
     * 

     * SocketImpl s;
     * ...
     * Boolean noDelay = (Boolean)(s.getOption(TCP_NODELAY));
     * if (noDelay.booleanValue()) {
     *     // true if TCP_NODELAY is enabled...
     * ...
     * }
     * 

* For options that take a particular type as a parameter, * getOption(int) will return the paramter's value, else * it will return java.lang.Boolean(false): *

     * Object o = s.getOption(SO_LINGER);
     * if (o instanceof Integer) {
     *     System.out.print("Linger time is " + ((Integer)o).intValue());
     * } else {
     *   // the true type of o is java.lang.Boolean(false);
     * }
     *