Hi Emil, while supporting server-sent events (or even websockets for that matter) would be great, this is basically a problem which has to be tackled in WSGI first in my opinion. That said, when you talk about a separate process, how would it look like (aside from using asycio), ie how would it use Django's current featureset which is basically blocking everywhere…
Cheers, Florian On Saturday, May 30, 2015 at 5:52:36 PM UTC+1, Emil Stenström wrote: > > Hi, > > This is the third feature proposal as part of my general drive for > getting Django to work better for javascript heavy sites. > > Support Server-Sent Events > -------------------------- > > If you want a snappy user experience, AJAX polling isn't enough. There > are two major ways to get out of the request-response cycle. Namely: > websockets and server-sent events. > > Websockets are complicated beasts, and getting cross-browser support for > them requires implementing several protocol versions. They are also > bidirectional, meaning you can send stuff to the server with them. > > Server-Sent Events use normal HTTP, and are natively supported > everywhere except Internet Explorer. Since they don't use a custom > protocol there are several polyfills that enable IE support too, > bringing browser compliance close to 100%. SSE only supports sending > data from server to client, not the other way around. > > The ease of implementation for server-sent events makes it a much better > Django fit in my opinion. Also, I don't think the need for client -> > server requests is that big, you can easily solve that with AJAX calls > instead. > > More reading on how it works: > http://www.html5rocks.com/en/tutorials/eventsource/basics/ > > --- > > Just like websockets, server-sent events rely on persistent connections > to each connected client. This means that we need a separate process to > make this work properly. I understand this is a controversial > suggestion, but it allows the rest of Django to continue working like > before, and still offer async support to users. It's the best of two > worlds. > > So how would you implement such a process in a performant way? With > Python 3's asyncio package (for Python 2 support there's trollius: > https://pypi.python.org/pypi/trollius). This means no external > dependencies (except for old pythons). > > You would start the process separately, add a script tag to your page, > and all clients that connected to the page would be connected to the > process. Now Django could push messages through that process as part of > the request-response cycle, and all clients would be notified. Other > processes (a cron job?) could do the same. > > Simply stated: we would finally get async support in Django, without > having to rewrite large parts of Django. Also, we need no persistent > message storage. Connected clients get the messages, then it's discarded. > > There is existing work on this that could be a starting point for a more > Django:y API: https://github.com/brutasse/asyncio-sse > > --- > > I think server-sent events would be a great reason to choose Django over > other frameworks. It would finally answer the request for "async" > features in Django, with a system that's as easy to setup (just start > the process) as to implement. > > Would anyone we willing to work with me on this? Do you think it makes > sense to put this in Django? I don't see any need for this code to > change often, and it fits well with the "building apps quickly and with > less code" mantra. > > Thoughts? Ideas? > > (And yes, this idea would work great together with the js template > rendering. Pushing database updates from the server to the client, and > they instantly updating the template accordingly) > > Regards, > > Emil Stenström > Twitter: @EmilStenstrom > -- You received this message because you are subscribed to the Google Groups "Django developers (Contributions to Django itself)" group. To unsubscribe from this group and stop receiving emails from it, send an email to django-developers+unsubscr...@googlegroups.com. To post to this group, send email to django-developers@googlegroups.com. Visit this group at http://groups.google.com/group/django-developers. To view this discussion on the web visit https://groups.google.com/d/msgid/django-developers/82e2e4c2-ebc2-4d65-a1f0-5947e2ceed2e%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
