Fascinating and exciting. Up until now, my go-to tactic for contain WSGI inside async has been to use the WSGI container in twisted.web (this is how hendrix works: https://github.com/hangarunderground/hendrix).
However, if we're talking about an actual flag in WSGI (like wsgi.async_input), this is the probably the most significant game-changer of all the proposals so far. On Tue, Oct 14, 2014 at 9:47 AM, Guido van Rossum <gu...@python.org> wrote: > I am fascinated by the new WSGI - HTTP/2 discussions. I don't have much to > contribute, because my own experience with web development is either very > old (when CGI was new and exciting) or uses corporate frameworks where > there's a huge set of layers between the app code and the external network > (e.g. Google, Dropbox). > > I have strong emotional responses to some of the discussion topics (e.g. I > feel that REMOTE_ADDR should represent the public IP address from which the > request originated, not the internal address of a reverse proxy, since my > use cases for it are all about blocking or rate-limiting specific clients, > and I assume the network between the reverse proxy and the app server is > secure) but I am sure there are already enough voices here and I trust that > the sig will come up with the right answers (even if they override my gut > feelings!). > > My most recent foray into web stuff was writing a small web crawler as an > example for asyncio (PEP 3156, a.k.a. tulip). The crawler is written in > Python 3 and the source code is here: > https://github.com/aosabook/500lines/blob/master/crawler/crawling.py and it > supports several advanced HTTP features: TLS, connection reuse, chunked > transfer encoding, redirects (but not compression -- I think it would be > straightforward to add, but the code would then exceed the 500 lines limit > imposed by the book). > > Perhaps the main lesson I learned from writing this is how different yet > similar web code looks when you use an asynchronous framework. Which makes > me wonder -- can there be a future where you can write your web app as an > asyncio coroutine? > > It looks like the WSGI protocol already supports asynchronously producing > the response (using yield), and I don't think asyncio would have a problem > with converting this convention to its own "yield from" convention. However, > the situation is different for reading the request body. The app can read > this in dribs and drabs if it wants to, by reading limited amounts of data > from environ['wsgi.input'], but in an asyncio-driven world reading > operations should really be marked with "yield from" (or perhaps just yield > -- again, I'm sure an adaptor won't have a problem with this). > > I'm wondering if a small extension to the WSGI protocol might be sufficient > to support this: the special environ variable "wsgi.async_input" could > optionally be tied to a standard asyncio stream reader > (https://docs.python.org/3/library/asyncio-stream.html#streamreader), from > which bytes can be read using "yield from stream.read([nbytes])" or "yield > from stream.readline()". > > Thinking a little more about this, it might be better if an async app could > be a regular asyncio coroutine. In this case it might be better if > start_response() were to return an asyncio stream writer > (https://docs.python.org/3/library/asyncio-stream.html#streamwriter) and if > it was expected to produce all its output by writing to this stream. > > Anyway, I think I'm getting ahead of myself, but I do think it would be nice > if the next WSGI standard supported asyncio. For older Python versions it > could then instead support Trollius (https://pypi.python.org/pypi/trollius), > a backport of asyncio that supports Python 2.7 and 3.2 (and newer). > > -- > --Guido van Rossum (python.org/~guido) > > _______________________________________________ > Web-SIG mailing list > Web-SIG@python.org > Web SIG: http://www.python.org/sigs/web-sig > Unsubscribe: > https://mail.python.org/mailman/options/web-sig/justin%40justinholmes.com > -- jMyles Holmes Chief Chocobo Breeder, slashRoot slashRoot: Coffee House and Tech Dojo New Paltz, NY 12561 845.633.8330 _______________________________________________ Web-SIG mailing list Web-SIG@python.org Web SIG: http://www.python.org/sigs/web-sig Unsubscribe: https://mail.python.org/mailman/options/web-sig/archive%40mail-archive.com
