socket_create_pair

<?php
$sockets = array();

/* On Windows we need to use AF_INET */
$domain = (strtoupper(substr(PHP_OS, 0, 3)) == 'WIN' ? AF_INET : AF_UNIX);

/* Setup socket pair */
if (socket_create_pair($domain, SOCK_STREAM, 0, $sockets) === false) {
    echo "socket_create_pair failed. Reason: ".socket_strerror(socket_last_error());
}
/* Send and Receive Data */
if (socket_write($sockets[0], "ABCdef123\n", strlen("ABCdef123\n")) === false) {
    echo "socket_write() failed. Reason: ".socket_strerror(socket_last_error($sockets[0]));
}
if (($data = socket_read($sockets[1], strlen("ABCdef123\n"), PHP_BINARY_READ)) === false) {
    echo "socket_read() failed. Reason: ".socket_strerror(socket_last_error($sockets[1]));
}
var_dump($data);

/* Close sockets */
socket_close($sockets[0]);
socket_close($sockets[1]);
?>

<?php
$ary = array();
$strone = 'Message From Parent.';
$strtwo = 'Message From Child.';

if (socket_create_pair(AF_UNIX, SOCK_STREAM, 0, $ary) === false) {
    echo "socket_create_pair() failed. Reason: ".socket_strerror(socket_last_error());
}
$pid = pcntl_fork();
if ($pid == -1) {
    echo 'Could not fork Process.';
} elseif ($pid) {
    /*parent*/
    socket_close($ary[0]);
    if (socket_write($ary[1], $strone, strlen($strone)) === false) {
        echo "socket_write() failed. Reason: ".socket_strerror(socket_last_error($ary[1]));
    }
    if (socket_read($ary[1], strlen($strtwo), PHP_BINARY_READ) == $strtwo) {
        echo "Received $strtwo\n";
    }
    socket_close($ary[1]);
} else {
    /*child*/
    socket_close($ary[1]);
    if (socket_write($ary[0], $strtwo, strlen($strtwo)) === false) {
        echo "socket_write() failed. Reason: ".socket_strerror(socket_last_error($ary[0]));
    }
    if (socket_read($ary[0], strlen($strone), PHP_BINARY_READ) == $strone) {
        echo "Received $strone\n";
    }
    socket_close($ary[0]);
}
?>