Get completion status for all enrolled students on a course?

Is there a way to get the completion status for all enrolled students on a course using a web service? I'm aware of "core_completion_get_course_completion_status" but this appears to be restricted to a single user per web services call, so would be incredibly inefficient and slow to get completion status for all the students on a course.

Or alternatively, is there some plugin that can provide this functionality, or allow securely authenticated access to query the database directly via a web service (we obviously don't want to expose our MySQL directly to the internet!)

Thanks,

Dan Jackson (Network & Systems Engineer)

Long Road Sixth Form College

Cambridge, UK.