Upgrade to Pro
— share decks privately, control downloads, hide ads and more …
Speaker Deck
Features
Speaker Deck
PRO
Sign in
Sign up for free
Search
Search
Architecting with Channels
Search
Andrew Godwin
July 19, 2016
Programming
2
1.1k
Architecting with Channels
My keynote from DjangoCon US 2016.
Andrew Godwin
July 19, 2016
Tweet
Share
More Decks by Andrew Godwin
See All by Andrew Godwin
Reconciling Everything
andrewgodwin
1
270
Django Through The Years
andrewgodwin
0
170
Writing Maintainable Software At Scale
andrewgodwin
0
400
A Newcomer's Guide To Airflow's Architecture
andrewgodwin
0
330
Async, Python, and the Future
andrewgodwin
2
620
How To Break Django: With Async
andrewgodwin
1
690
Taking Django's ORM Async
andrewgodwin
0
690
The Long Road To Asynchrony
andrewgodwin
0
620
The Scientist & The Engineer
andrewgodwin
1
720
Other Decks in Programming
See All in Programming
新宿駅構内を三人称視点で探索してみる
satoshi7190
2
120
仕様変更に耐えるための"今の"DRY原則を考える
mkmk884
9
3.2k
たのしいSocketのしくみ / Socket Under a Microscope
coe401_
8
1.4k
LINE messaging APIを使ってGoogleカレンダーと連携した予約ツールを作ってみた
takumakoike
0
120
データの整合性を保つ非同期処理アーキテクチャパターン / Async Architecture Patterns
mokuo
55
19k
1年目の私に伝えたい!テストコードを怖がらなくなるためのヒント/Tips for not being afraid of test code
push_gawa
1
630
データベースのオペレーターであるCloudNativePGがStatefulSetを使わない理由に迫る
nnaka2992
0
240
Learning Kotlin with detekt
inouehi
1
150
DevNexus - Create AI Infused Java Apps with LangChain4j
kdubois
0
100
iOSでQRコード生成奮闘記
ktcryomm
2
110
バッチを作らなきゃとなったときに考えること
irof
2
530
Amazon Bedrockマルチエージェントコラボレーションを諦めてLangGraphに入門してみた
akihisaikeda
1
110
Featured
See All Featured
YesSQL, Process and Tooling at Scale
rocio
172
14k
4 Signs Your Business is Dying
shpigford
182
22k
The Illustrated Children's Guide to Kubernetes
chrisshort
48
49k
[RailsConf 2023 Opening Keynote] The Magic of Rails
eileencodes
28
9.3k
Practical Tips for Bootstrapping Information Extraction Pipelines
honnibal
PRO
12
1k
Designing on Purpose - Digital PM Summit 2013
jponch
117
7.1k
Evolution of real-time – Irina Nazarova, EuRuKo, 2024
irinanazarova
6
570
Visualizing Your Data: Incorporating Mongo into Loggly Infrastructure
mongodb
45
9.4k
Improving Core Web Vitals using Speculation Rules API
sergeychernyshev
10
520
[RailsConf 2023] Rails as a piece of cake
palkan
53
5.3k
Creating an realtime collaboration tool: Agile Flush - .NET Oxford
marcduiker
27
1.9k
Making the Leap to Tech Lead
cromwellryan
133
9.1k
Transcript
None
Andrew Godwin Hi, I'm Django core developer Senior Software Engineer
at Used to complain about migrations a lot
2010
WebSockets
WebSockets (and Eventlet)
2012
None
2014
"django-onair"
2015
Channels
Born from WebSockets
Born from WebSockets Expanded to be more
The "real hard problem"
Asynchronous coordination
Why?
WebSockets don't magically solve everything
Architecture is about tradeoffs
Bidirectional, low overhead Complex client-side, compatibility CONS PROS
Streaming updates Chat applications Collaborative editing Game backends
Broadcast
Server Client 1 Client 2 Client 3 Client 4
Server Client 1 Client 2 Client 3 Client 4 Server
Server Client 1 Client 2 Client 3 Client 4 Server
The "hard problem"
Channels is a foundation for runnng 'async' at scale
WebSockets Task offloading Chat/Email integration IoT protocols
What makes it hard?
Stateful connections Internal network Bottlenecks
Server Server Django Script ASGI "Send to channel X" "Receive
from channel X" "Send to group Y" "Add channel X to group Y" "Remove channel X from group Y"
Server Server Django Script ASGI ASGI ASGI ASGI Redis
Server Server Django Script ASGI ASGI ASGI ASGI Shared Memory
Server Server Django Script ASGI ASGI ASGI ASGI Shared Memory
Redis Redis
bit.ly/asgi-spec
Channels wraps the low-level ASGI operations
Think of it as the "Django bit" of a larger
whole.
Daphne HTTP/WebSocket Server Channels Django integration asgi-redis Redis backend asgi-ipc
Local memory backend asgiref Shared code and libs
What does Channels provide? Routing Consumers Sessions Auth Helpers By
channel, URL, etc. Standardised message handling Cross-network persistence on sockets Including HTTP cookies on WebSocket runserver, runworker, debugging info
Putting it to use Let's make a chat!
Consumers def on_connect(message): Group("chat").add(message.reply_channel) def on_receive(message): Group("chat").send({"text": message["text"]}) def on_disconnect(message):
Group("chat").discard(message.reply_channel) websocket.connect websocket.receive websocket.disconnect
Routing from channels import route routing = [ route("websocket.connect", on_connect),
route("websocket.receive", on_receive), route("websocket.disconnect", on_disconnect) ]
Class-based from channels import route_class routing = [ route_class(ChatConsumer), ]
from channels.generic.websockets class ChatConsumer(WebsocketConsumer): def connection_groups(self): return ["chat"] def receive(self, text): self.group_send("chat", text=text) Routing
Full worked example github.com/andrewgodwin/channels-examples
Liveblog
Liveblog
Data Binding Multiplexing &
class IntegerValue(models.Model): name = models.CharField(max_length=100, unique=True) value = models.IntegerField(default=0) class
IntegerValueBinding(WebsocketBinding): model = IntegerValue stream = "intval" def check_permission(self, user, action, instance): return True def group_names(self, instance, action): return ["binding.values"]
Demo Do I dare?
More in channels-examples!
Custom Protocols
Decompose into messages Email email.send, email.receive Slack slack.receive, slack.send, slack.joined,
... MQTT mqtt.subscribe, mqtt.unsubscribe, mqtt.send, ...
Write a custom server Use asyncio, Twisted, Gevent, etc Server
takes path to ASGI channel layer instance (CLI/config file) Roll layer.send, layer.receive_many into your event loop
Write Django consumers Same codebase as the main project Optional
routing/per-worker channel limiting
IRC Worker ASGI Worker Worker Email MQTT Scheduler HTTP/WS Custom
Daemon
Channels is a tool for you to use
There's more to be done (and some funding for it)
1995 You are a desktop app 2005 You are a
website 2015 You are a rich web/mobile app 2025 ?
What are the goals of a framework? Do we adapt?
Let's keep Django and Python a great choice for complex
backends
Thanks. Andrew Godwin @andrewgodwin channels.readthedocs.io github.com/andrewgodwin/channels-examples