screensaver.php:
<?php
$d 
= new Dbus;
$n $d->createProxy(
    
"org.gnome.ScreenSaver",
    
"/org/gnome/ScreenSaver",
    
"org.gnome.ScreenSaver"
);

var_dump($n->GetActive());
$n->SetActivetrue );
var_dump($n->GetActive());
sleep(5);
$n->SetActivefalse );
?>