I was able to connect my Moodle v3.4 to Moodle v1.9 using the OKTech web services.
First test was to retrieve the courses of my Moodle v1.9 user.
I think, this way I can communicate between the two systems, so I can
- in Moodle v3.4 I can initiate backup process remotely in Moodle v1.9
- check if the backup process was finished? (not sure yet, how I will check this...)
- check if the resulted backup filename exists
- move resulted backup file to Moodle v3.4 filesystem repository
I hope I will get it work.