The easiest way to add WebSockets to Django

http://jpadilla.com/post/74391616727/the-easiest-way-to-add-websockets-to-django

by mcpherson • 12 years ago

50 16 12 years ago

jpdlla4• 12 years ago

Author here. Let me know if you have any questions or feedback.

fredley• 12 years ago

Just this last week I started working on a new project with django-socketio, and I'm pretty happy with it so far. Why is django-websocket-request better?

jpdlla4• 12 years ago

I did look into django-socketio when doing research, but never actually used it. django-websocket-request is way more simple, because it does way less and doesn't cover as much as django-socketio. For example, django-socketio is bound to only using socket.io, but it also includes a whole channel subscription and broadcast system so you can send messages from the server to specific channels. django-websocket-request only enables you to add a WebSocket layer over your already existing REST API / Views. I'll eventually have to look into doing things that django-socketio does.

falcolas4• 12 years ago

Does SockJSRouter do any magic to ensure that wrapped handlers won't block the Tornado event loop?

jpdlla4• 12 years ago

Not 100% sure but I would hope so. https://github.com/mrjoes/sockjs-tornado

vivekprakash• 12 years ago

This question is more related to websockets. I have seen that they use different protocol and doesn't work behind proxies or firewalls most of the time. How do you handle this?

falcolas4• 12 years ago

Using websockets relies on a proxy that doesn't pass just the headers/body, but instead sends all packets in both directions. Nginx proxies do this, Apache requires a special proxy module.

Firewalls don't typically care, since it's effectively a long lived HTTP request, unless it digs into all of the packets and filters there.

swah• 12 years ago

IIRC SSL is recommended for Websockets.

falcolas4• 12 years ago

No, it's really not that easy, sorry.

Looking at the code, you're not actually doing anything with websockets here. There's no handshake parsing, there's no open socket object to pass data back and forth on, there's nothing actually websockety about this.

Instead, you seem to have a simple ajax endpoint.

Or am I missing something?

[EDIT] Clarifying why I said it's not that easy, since that seems snarky as I read it again. To properly do websockets in Django, you have to write your own runserver, which allows processes up the stack to capture the raw socket, perform the websocket handshake methods, and do proper parsing of the incoming data to break the messages on the sentinel values.

I recently tried to do this, and the one package that did this wouldn't work with Django 1.6, and we would have to give up our flup runfcgi, which I wasn't ready to do.

gizmo• 12 years ago

I only looked at it for a second or so, but it looks like it's a simple json proxy. You put a webserver with persistent connections on one end (Tornado in the example code) and a regular django environment side by side. The web socket requests are translated in to GET/PUT/POST requests, are pushed to django, django responds and the response is pushed to the client.

So from django's point of view there are stateless JSON requests and responses, so django's happy. The python proxy code is a lightweight wrapper that doesn't have to understand any business logic, so that's pretty straightforward as well.

falcolas4• 12 years ago

I see where I was confused; I looked at the actual code itself, not the example where tornado was living and being used.

What are the advantages of this over normal AJAX requests, given that it's all using the single request, single response mode of operation (and you can compress/cache AJAX requests/responses, which websockets doesn't support yet).

nilsbunger• 12 years ago

This could be useful. A few questions:

1) can you describe the tornado part of the system? The blog post isn't really clear on that.

2) how do you associate websocket sessions with browser sessions?

3) how do you handle server-to-client notifications? ie. a celery task completes and you want to notify the client.

4) Is XSS a concern?

The easiest way to add WebSockets to Django

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