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ZeroServices
Boris Feld
October 27, 2013
Programming
0
86
ZeroServices
Présentation de ZeroServices, une libraire pour faire des services réseaux en P2P.
Boris Feld
October 27, 2013
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Transcript
ZeroServices FELD Boris - PyconFR 2013 lothiraldan@gmail.com
/me • FELD Boris - DevTools • Tornado FTW •
@lothiraldan un peu partout sur le web • https://github.com/Lothiraldan/ ZeroServices
ZeroService • Librairie pour écrire des Services P2P • Python2.x
• Very Alpha
ZeroServices Pourquoi ?
Besoins • AutoDiscovery • Multicast / Unicast • Découverte des
pertes de pairs
Network is difficult
Peer To Peer is difficult
Choix technologiques
Pourquoi ØMQ ? • Sockets BSD trop bas niveau. •
RabbitMQ... NOPE. • ØMQ FTW. • L’ioloop est packagée dans PyZMQ.
AutoDiscovery UDP Multicast
Communication Unicast / Multicast ZeroMQ
Découverte des pertes Heartbeating (to do)
None
Retour d’expérience
L’asynchrone c’est difficile
Tester de l’asynchrone c’est douloureux
Quelques trucs • Isoler au maximum la partie asynchrone •
La tester avec des mocks • Mocker la partie asynchrone
Exemple class ZeroMQMediumTestCase(unittest.TestCase): def setUp(self): self.service = ServiceMock() self.ioloop =
IOLoop.instance() self.medium = ZeroMQMedium(self.service, ioloop=self.ioloop) def testRegister(self): self.medium.register() self.ioloop.start() self.assertEqual(self.service.on_registration_message.call_count, 1)
Exemple II class BaseServiceTestCase(unittest.TestCase): def setUp(self): self.medium = TestMedium() self.service
= BaseService(self.medium) def testOnRegistration(self): node_info = {'name': 'Service 1'} self.service.on_registration_message(node_info) self.assertEqual(self.medium.send_registration_answer.call_count, 1)
Les topologies réseaux est hétérogène
Vous allez toujours avoir des topologies de réseau tordues
Au choix • Firewall • NAT • VPN • DMZ
• Pas d’UDP Multicast
None
Traitez les quand ils arrivent
Pas de solutions magiques en P2P
Des techniques • Utiliser le port 443 ou 80 •
UDP Hole Punching • Encapsuler le traffic dans HTTP
Une solution ? • Avoir un pair central • Qui
forward le traffic
ZeroService is not perfect • Pas d’ack pour les messages
• Pas d’heartbeat • Une socket par message sortant • UDP Multicast / ZeroConf • Marche en LAN. Pas en WAN.
Exemple
Le service de chat class ChatService(BaseService): def __init__(self, username): self.username
= username super(ChatService, self).__init__(ZeroMQMedium(self, port_random=True)) def service_info(self): return {'name': self.username}
Le service de chat class ChatService(BaseService): def on_event(self, message_type, message):
"""Called when a multicast message is received """ msg = {'type': message_type} msg.update(message) self.send_to_all_clients(json.dumps(msg)) def on_message(self, message_type, **kwargs): """Called when an unicast message is received """ msg = {'type': message_type} msg.update(kwargs) self.send_to_all_clients(json.dumps(msg)) def on_new_node(self, node_info): """Called when a new peer joins """ msg = json.dumps({'type': 'user_join', 'id': node_info['node_id'], 'name': node_info['name']}) self.send_to_all_clients(msg) def on_node_close(self, node_info): """Called when a peer leaves """ msg = json.dumps({'type': 'user_leave', 'id': node_info['node_id'], 'name': node_info['name']}) self.send_to_all_clients(msg)
La partie Tornado class MainHandler(web.RequestHandler): def get(self): return self.render('chat.html', port=int(sys.argv[2]),
name=sys.argv[1])
La partie Tornado clients = [] class WebSocketHandler(websocket.WebSocketHandler): def open(self):
clients.append(self) for node_id, node in s.nodes_directory.items(): msg = json.dumps({'type': 'user_join', 'id': node_id, 'name': node['name']}) self.write_message(msg) def on_close(self): clients.remove(self) def on_message(self, message): message = json.loads(message) if message['type'] == 'message': msg = {'username': sys.argv[1], 'message': message['data']['message']} s.publish(str(message['type']), msg) elif message['type'] == 'direct_message': msg = {'from': sys.argv[1], 'message': message['data']['message']} s.send(message['data']['to'], msg, msg_type=str(message['type']))
Chat.py urls = [ (r"/", MainHandler), (r"/websocket", WebSocketHandler), (r"/static/(.*)", web.StaticFileHandler,
{"path": "."})] if __name__ == '__main__': application = web.Application(urls, debug=True) application.listen(int(sys.argv[2])) try: ioloop.IOLoop.instance().add_timeout(time() + 1, s.medium.register) ioloop.IOLoop.instance().start() except KeyboardInterrupt: s.close() for client in clients: client.close()
La demo chat • 69 lignes de python • Pas
de serveur central • API qui se veut simple
DEMO !
Questions ?