Accessing moodle's ques(tion) bank

I am creating an online learning platform where we are using Moodle for entering and storing the Questions. I need to create a wrapper using which I can access Moodle's question bank from my application. What will be the best way to do it: a plugin or a web service? Is there anything like this already? There is already a export feature in moodle but I don't want to export all questions at one go. Instead fetch the questions by Ids or other parameters. Any pointers will be really helpful. Thanks a lot.