Snippets are unofficial and unmaintained.
This is an archived view of user-submitted snippets. Despite being hosted on the Flask site, they are not official. No Flask maintainer has curated or checked the snippets for security, correctness, or design.
Talking from the client to the server is easy. Just use
XMLHttpRequest to send an HTTP request to the server and you're done. But what about talking from the server to the client in realtime?
Turns out WSGI and traditional frameworks are not exactly suited for that. However they don't have to since you can keep the web socket connection around somewhere else.
This is how Juggernaut works. It's a server written with node that uses redis to communicate with your server side application and websockets, long polling or flash to talk to the client.
So how does it work? First of all you need to have Juggernaut installed and running (also make sure to have redis running):
$ npm install -g juggernaut $ juggernaut
For talking to juggernaut from Python you can use redis directly or the
juggernaut client library:
pip install juggernaut
At that point you can use juggernaut to talk to your clients. On the client side you need to include the juggernaut driver script and subscribe to a channel:
In this case Juggernaut is running on
localhost:8080. It makes sense to make this configurable.
To send a message now with Python you can do it like this:
>>> from juggernaut import Juggernaut >>> jug = Juggernaut() >>> jug.publish('channel', 'The message')
If redis is running somewhere else you will need to pass a redis instance to
Juggernaut and the
For a full fledged example see Flask-Pastebin.
This snippet by Armin Ronacher can be used freely for anything you like. Consider it public domain.