List of avaliable web service methods in Moodle can be found here
General developer forum
Activity completion on plugin
I made my application with AJAX and it worked but I don't want to rely on cron. I remade using the completion library but I don't know how to find the id of the activities that are required to complete the course, so I can ignore activities that won't be a progress on the map I'm making, do you know where I should look?