class controller:
		#during initialization a structure for saving session_id's of users should be created
		def __init__(self):
			pass

		#checks login data, creates session and gives coookie with session id
		def login(user)
			pass
		#checks session_id from cookie and returns user data
		def check_if_logged(id_from_cookie)
			pass

		def import_laboratories_or_projects(csv_file)
			pass
		def import_students(file)
			pass

		def add_subject(subject)
			pass
		def add_realization(subject)
			pass

		def sign_up_for_project_or_laboratory(participation)
			pass
		def delete_participation(participation)
			pass

		def get_subjects()
			pass
		def get_current_realizations(subject)
			pass

		def get_projects_or_laboratories_for_realization(realization)
			pass