baseimage-tutorial-framework/lib/tfw/networking/server/controller_responder.py

from tfw.networking.controller_connector import ControllerConnector
from tfw.networking.serialization import deserialize_all, serialize_all


class ControllerResponder:
    def __init__(self, fsm):
        self.fsm = fsm
        self.controller_connector = ControllerConnector()
        self.controller_connector.register_callback(self.handle_controller_request)
        self.controller_request_handlers = {
            'solution_check': self.handle_solution_check_request,
            'test': self.handle_test_request
        }

    def handle_controller_request(self, stream, msg_parts):
        key, data = deserialize_all(*msg_parts)
        response = self.controller_request_handlers[key](data)
        stream.send_multipart(serialize_all(key, response))

    def handle_test_request(self, data):
        return 'OK'

    def handle_solution_check_request(self, data):
        return {
            'solved': self.fsm.is_solved(),
            'message': 'solved' if self.fsm.is_solved() else 'not solved'
        }