header('Cache-Control: no-cache');  
header('Content-Type: text/event-stream; charset=utf-8');
$id=111;
$arr=[333,444,555];
echo "id: $id" . PHP_EOL;
echo "data: ".json_encode($arr).PHP_EOL;
echo 'retry: 2000', PHP_EOL, PHP_EOL; //2000 is miliseconds