Артём Малышев (Positive Technologies) - Django Channels - ответ современному вебу

Доклад с Moscow Python Conf 2016 (http://conf.python.ru)
Видео: https://conf.python.ru/django-channels-otvet-sovremennomu-vebu/

Я senior python developer в компании Positive Technologies. Последние два года занимаюсь разработкой распределённых систем. Спикер PyCon Russia, MoscowPython и Rannts Meetup. В докладе я расскажу о назначение и устройстве Django Channels. Давно прошли времена, когда все сайты работали в режиме "запрос-ответ". Пользователи хотят интерактивности и отзывчивости, программисты хотят websocket'ы, HTTP/2 стремительно набирает популярность. Классические WSGI фреймворки перестают соответствовать реалиям жизни. Вы узнаете каким образом в Django реализована поддержка асинхронных протоколов, решение каких задач можно отдать этой технологии, а где лучше использовать tornado или aiohttp.

Transcript

1. 1 DJANGO CHANNELS ARTEM MALYSHEV @PROOFIT404
2. 2 BRING DJANGO TO THE ASYNC NETWORKING
3. 3 BUT WE ARE ALREADY THERE twisted eventlet gevent tornado asyncio
4. 4 AND DJANGO IS SYNC IN ITS CORE
5. 5 WSGI def app(environ, callback): status, headers = '200 OK', [] callback(status, headers) return ['Hello world!\n']
7. 7 OK, BUT IT IS 2016 DUDE
8. 8 PROGRESSIVE WEB APPS interactive communication responsive design push notifications works offline
10. 10 IT'S ALL DIFFERENT PERSISTENT STATEFUL CONNECTIONS
15. 15 ASGI
16. 16 ASGI IS a standard interface between network protocol servers and Python applications
17. 17 CHANNEL
18. 18 CHANNEL IS an ordered, first-in first-out queue with message expiry and at-most-once delivery to only one listener at a time
19. 19 CONSUMERS
20. 20 ACCEPT WEBSOCKET MESSAGE def ws_message(message): message.reply_channel.send({ 'text': message.content['text'], })
21. 21 ROUTING from channels.routing import route from myapp.consumers import ws_message channel_routing = [ route('websocket.receive', ws_message), ]
22. 22 SETTINGS CHANNEL_LAYERS = { 'default': { 'BACKEND': 'asgiref.inmemory', 'ROUTING': 'myproject.routing', }, }
23. 23 ASGI APP import os from channels.asgi import get_channel_layer os.environ.setdefault( 'DJANGO_SETTINGS_MODULE', 'myproject.settings', ) channel_layer = get_channel_layer()
24. 24 DEPLOY $ gunicorn myproject.wsgi $ daphne myproject.asgi:channel_layer $ django-admin runworker
25. 25 REPLY CHANNEL
27. 27 GROUPS
28. 28 CONSUMERS from channels import Group def ws_connect(message): Group('chat').add(message.reply_channel) def ws_disconnect(message): Group('chat').discard(message.reply_channel) def ws_message(message): Group('chat').send({ 'text': message.content['text'], })
29. 29 ROUTING from channels.routing import route from myapp.consumers import * channel_routing = [ route('websocket.connect', ws_connect), route('websocket.disconnect', ws_disconnect), route('websocket.receive', ws_message), ]
30. 30 GENERIC CONSUMERS
31. 31 BASE CONSUMER from channels.generic import BaseConsumer class MyConsumer(BaseConsumer): method_mapping = { 'channel.name.here': 'method_name', } def method_name(self, message, **kwargs): pass
32. 32 WEBSOCKET CONSUMER from channels.generic import WebsocketConsumer class MyConsumer(WebsocketConsumer): def connection_groups(self): return ['chat'] def connect(self, message): pass def receive(self, text=None, bytes=None): self.send(text=text, bytes=bytes)
33. 33 ROUTING from channels import route_class from myapp import consumers channel_routing = [ route_class(consumers.MyConsumer), ]
34. 34 ROUTING
35. 35 FILTERS // app.js s = new WebSocket('ws://localhost:8000/chat/') # routing.py route('websocket.connect', ws_connect, path=r'^/chat/$')
36. 36 INCLUDES from channels import route, include blog_routes = [ route('websocket.connect', blog, path=r'^/stream/'), ] routing = [ include(blog_routes, path=r'^/blog'), ]
37. 37 MULTIPLEXING
38. 38 DEFINE MAPPING from channels import WebsocketDemultiplexer class Demultiplexer(WebsocketDemultiplexer): mapping = { 'intval': 'binding.intval', }
39. 39 ROUTING from channels import route_class, route from .consumers import Demultiplexer, ws_message channel_routing = [ route_class(Demultiplexer, path='^/binding/'), route('binding.intval', ws_message), ]
40. 40 MESSAGE CONTENT { "stream": "intval", "payload": { ... } }
41. 41 SESSIONS
42. 42 CHANNEL SESSION from channels.sessions import channel_session @channel_session def ws_connect(message): room = message.content['path'] message.channel_session['room'] = room Group('chat-%s' % room).add( message.reply_channel )
43. 43 HTTP SESSION from channels.sessions import http_session_user @http_session_user def ws_connect(message): message.http_session['room'] = room if message.user.username: ...
44. 44 MESSAGE ORDER
45. 45 ENFORCE ORDERING from channels.generic import WebsocketConsumer class MyConsumer(WebsocketConsumer): http_user = True slight_ordering = True strict_ordering = False def connection_groups(self, **kwargs): return ['chat']
46. 46 DATA BINDING
47. 47 BIND MODEL class IntegerValueBinding(WebsocketBinding): model = IntegerValue stream = 'intval' fields = ['name', 'value'] def group_names(self, instance, action): return ['intval-updates'] def has_permission(self, user, action, pk): return True
48. 48 REDIS LAYER
49. 49 REDIS LAYER SINC ON WORKERS ASYNC ON DAPHNE MSGPACK SHARDING
50. 50 CHANNEL IMPLEMENTATION >> SET "b6dc0dfce" "\x81\xa4text\xachello" >> RPUSH "websocket.send!sGOpfny" "b6dc0dfce" >> EXPIRE "b6dc0dfce" "60" >> EXPIRE "websocket.send!sGOpfny" "61"
51. 51 GROUP IMPLEMENTATION >> type group:chat zset >> ZRANGE group:chat 0 1 WITHSCORES 1) "websocket.send!sGOpfny" 2) "1476199781.8159261"
52. 52 PROBLEMS
53. 53 CALLBACK HELL
54. 54 CELERY
55. 55 CHANNELS IS NOT A TASK QUEUE
56. 56 CHANNELS CAN'T RETRY CANVAS ETA
57. 57 DJANGO FOR TODAY'S WEB
58. 58 QUESTIONS?