Good example from Javier.
For using in docker container you can use 0 as an address:
$address = '0';
To broadcast a message to all clients, you can use socket_write() for all required clients:
...
// Handle Input
foreach ($clients as $key => $client) {
if (in_array($client, $read)) {
...
if ($buf == 'message') {
$talkback = "$buf $key\n";
foreach ($clients as $curClient) {
socket_write($curClient, $talkback, strlen($talkback));
}
continue;
}
...
}
}
...