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Architecting with Channels

Architecting with Channels

My keynote from DjangoCon US 2016.

Andrew Godwin

July 19, 2016

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  1. 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"
  2. 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
  3. Routing from channels import route routing = [ route("websocket.connect", on_connect),

    route("websocket.receive", on_receive), route("websocket.disconnect", on_disconnect) ]
  4. 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
  5. 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"]
  6. 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
  7. 1995 You are a desktop app 2005 You are a

    website 2015 You are a rich web/mobile app 2025 ?