private static Registry instance;
protected Registry() {
dao = new DAO();
studyProgramFinder = new StudyProgramFinder(dao);
courseFinder = new CourseFinder(dao);
studentFinder = new StudentFinder(dao);
activityFinder = new ActivityFinder(dao);
milestoneFinder = new MilestoneFinder(dao);
graphFinder = new GraphFinder(dao);