using web service from one moodle to another moodle

I'm new with moodle and my senior ask me to do something.

I'm using two moodle. One moodle for the student study at home, I called it moodle study, and one moodle for the test, I call it moodle test. The moodle test running on local server so the student won't do the test outside the laboratory.But I want to make the student can see their test score from moodle test through the moodle study. 

I'm thinking of using a gradebook plugin on moodle study which return the test score from moodle. Can I use moodle webservice to get the score value? If I can, what thing should I do first?

Sorry for my bad english. And thank you.