stream_socket_pair

Description

stream_socket_pair() creates a pair of connected, indistinguishable socket streams. This function is commonly used in IPC (Inter-Process Communication).

Parameters

domain

The protocol family to be used: STREAM_PF_INET, STREAM_PF_INET6 or STREAM_PF_UNIX

type

The type of communication to be used: STREAM_SOCK_DGRAM, STREAM_SOCK_RAW, STREAM_SOCK_RDM, STREAM_SOCK_SEQPACKET or STREAM_SOCK_STREAM

protocol

The protocol to be used: STREAM_IPPROTO_ICMP, STREAM_IPPROTO_IP, STREAM_IPPROTO_RAW, STREAM_IPPROTO_TCP or STREAM_IPPROTO_UDP

Return Values

Returns an array with the two socket resources on success, or false on failure.

Examples

A stream_socket_pair() example

This example shows the basic usage of stream_socket_pair() in Inter-Process Communication.

<?php

$sockets = stream_socket_pair(STREAM_PF_UNIX, STREAM_SOCK_STREAM, STREAM_IPPROTO_IP);
$pid     = pcntl_fork();

if ($pid == -1) {
     die('could not fork');

} else if ($pid) {
     /* parent */
    fclose($sockets[0]);

    fwrite($sockets[1], "child PID: $pid\n");
    echo fgets($sockets[1]);

    fclose($sockets[1]);

} else {
    /* child */
    fclose($sockets[1]);

    fwrite($sockets[0], "message from child\n");
    echo fgets($sockets[0]);

    fclose($sockets[0]);
}

?>

The above example will output something similar to:

child PID: 1378
message from child