System upgrade with ubus

Hello,

I'm unable to find solid information regarding remote system update with ubus (except for https://wiki.openwrt.org/doc/ubus/system marked as TODO). So far I was using something like: put file, execute sysupgrade command, all with ubus. So here comes the question:

What is the recommended way of performing system upgrade remotely?

@pbn Friend did get the solution about it get then let me know also I still didn't find the solution about it.