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

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# Copyright (C) 2018 Avatao.com Innovative Learning Kft.
# All Rights Reserved. See LICENSE file for details.
from abc import ABC, abstractmethod
from tornado.web import Application
from tfw.networking.event_handlers import ServerUplinkConnector
from tfw.networking.server import EventHandlerConnector
from tfw.networking import MessageSender
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from tfw.config.logs import logging
from .zmq_websocket_proxy import ZMQWebSocketProxy
LOG = logging.getLogger(__name__)
class TFWServer:
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"""
This class handles the proxying of messages between the frontend and event handers.
It proxies messages from the "/ws" route to all event handlers subscribed to a ZMQ
SUB socket.
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"""
def __init__(self):
self._event_handler_connector = EventHandlerConnector()
self._uplink_connector = ServerUplinkConnector()
self.application = Application([(
r'/ws', ZMQWebSocketProxy,{
'event_handler_connector': self._event_handler_connector,
'message_handlers': [self.handle_trigger, self.handle_recover],
'frontend_message_handlers': [self.save_frontend_messages]
})]
)
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self._frontend_messages = FrontendMessageStorage()
def handle_trigger(self, message):
if 'trigger' in message:
LOG.debug('Executing handler for trigger "%s"', message.get('trigger', ''))
self._uplink_connector.send_to_eventhandler({
'key': 'fsm',
'data': {
'command': 'trigger',
'value': message.get('trigger', '')
}
})
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def handle_recover(self, message):
if message['key'] == 'recover':
self._frontend_messages.replay_messages(self._uplink_connector)
def save_frontend_messages(self, message):
self._frontend_messages.save_message(message)
def listen(self, port):
self.application.listen(port)
class MessageStorage(ABC):
def __init__(self):
self.saved_messages = []
def save_message(self, message):
if self.filter_message(message):
self.saved_messages.extend(self.transform_message(message))
@abstractmethod
def filter_message(self, message):
raise NotImplementedError
def transform_message(self, message):
yield message
class FrontendMessageStorage(MessageStorage):
def filter_message(self, message):
return message['key'] in ('message', 'dashboard', 'queueMessages')
def transform_message(self, message):
if message['key'] == 'queueMessages':
yield from MessageSender.generate_messages_from_queue(message)
else:
yield message
def replay_messages(self, connector):
for message in self.saved_messages:
connector.send(message)