[zgintasz]

If I understood correctly, in OnPlayerConnect add player's id and player's name, in OnPlayerDisconnect remove it. Then, connect using php to mysql and check if the name is in mysql, if yes - player is connected, if not - player isn't connected. For communicating you can use sockets plugin or make another mysql table and with timer in server check if there is a "task" in mysql, after completing "task" remove that field from mysql, for example:
for what player | task
Player_Name | addscore 10
if there is set task, do it and remove that field.
I really don't know how to explain easily, hope you understood .