I am currently developing a moodle app on Android. I am trying to figure out how to use web services to upload an assignment and submit it. The idea is to use core_file_upload first to upload a file and get a draft id, then use mod_assign_save_submission to submit it. My question is the parameters of these functions. core_file_upload needs &contextid, $component, $filearea, $itemid, $filepath, $filename, $filecontent, $contextlevel, $instanceid, and mod_assign_save_submission needs pulgindata. Can anyone explain to me what these parameters represent and what format should they be?