yes, 'post' is proper when a form is submitted ...
... but exactly I'm looking for that result: I see you understood
1) not 'on-the-fly' as I want, concurrence must be managed
2) noooo, if a php calls a php, I don't see why send data to client and then get it from there ...
3) same as 1, not 'on-the-fly' as I want
sessions ...