baseimage-tutorial-framework/src/app/handlers/zmq_websocket_handler.py

import json
from tornado.websocket import WebSocketHandler
from util import parse_anchor_from_message

from event_handler_connector import EventHandlerConnector
from config.logs import logging
log = logging.getLogger(__name__)


class ZMQWebSocketHandler(WebSocketHandler):
    _event_handler_connector = EventHandlerConnector()  #<--------------------. TODO: how is __init__()
                                                        # fix: made it static | TODO: called more than once?
    def __init__(self, application, request, **kwargs): #---------------------'
        super().__init__(application, request, **kwargs)

    def open(self, *args, **kwargs):
        log.debug('WebSocket connection initiated')
        self._event_handler_connector.register_callback(self.zmq_callback)

    def zmq_callback(self, msg_parts):
        anchor, data = msg_parts
        log.debug('Received on pull socket: {}'.format(data.decode()))
        self.write_message(data.decode())

    def on_message(self, message):
        log.debug('Received on WebSocket: {}'.format(message))
        self.send_message(*self.make_response(message))

    def make_response(self, message):
        raise NotImplementedError

    def send_message(self, message: str, anchor: str = None):
        self._event_handler_connector.send_message(message, anchor)

    def on_close(self):
        pass

    # much secure, very cors, wow
    def check_origin(self, origin):
        return True


class FSMManagingSocketHandler(ZMQWebSocketHandler):
    def __init__(self, FSM, application, request, **kwargs):
        super().__init__(application, request, **kwargs)
        self.fsm = FSM()
        self.fsm.subscribe_message_handler(self.handle_fsm_message)

    def handle_fsm_message(self, message):
        self._event_handler_connector.send_message(message)

    def make_response(self, message):
        self.fsm.trigger(parse_anchor_from_message(message), message=message)
        anchor = 'FSMUpdate'
        response = {'anchor': anchor,
                    'data': {'current_state': self.fsm.state,
                             'valid_transitions':
                                 [{'trigger': trigger} for trigger in self.fsm.machine.get_triggers()]}}
        return json.dumps(response), anchor