[Web-SIG] [extension] x-wsgiorg.flush
Phillip J. Eby
pje at telecommunity.com
Thu Oct 4 16:37:58 CEST 2007
At 03:53 PM 10/4/2007 +0200, Manlio Perillo wrote:
>Phillip J. Eby ha scritto:
> > At 10:57 AM 10/4/2007 +0200, Manlio Perillo wrote:
> >> Phillip J. Eby ha scritto:
> >> > [...]
> >> >> There is a problem here: a WSGI gateway is not allowed to send headers
> >> >> until the app_iter yields a non empty string or the iterator is
> >> exausted.
> >> >
> >> > Argh. You're right. I forgot about that bit. It has been a few too
> >> > many years since I worked on the spec. :)
> >> >
> >> 07-Dec-2003!
> >> And yet it seems that WSGI is not pervasively used.
> > What do you mean? Can you name a popular Python web framework or
> > library that doesn't either use or support WSGI?
>Django, as an example, uses WSGI "only as a backend".
That's still WSGI *support*.
>Django design is not based on WSGI, it is WSGI that is adapted for Django.
Yep - which is why we need WSGI 2. WSGI 1 achieved all its goals
*except* for being easy to write middleware and build frameworks on
it. It should be easier to use WSGI than to not use it.
> > That won't be possible in WSGI 2.0 - it's a purely synchronous API.
>This is the reason why I don't like WSGI 2.0 :).
>However I have to admit that developing a full asynchronous application
>is not easy, notably when we have to interact with a database and a
Right - in practice, there is not enough of a common async API for
Python to make it practical to implement asynchronousness in WSGI
itself. At least, in the last three years nobody has made a
practical proposal for it. In practice, if you want to write a
fully-async web app you must use Twisted or a similar framework and
commit to using its API. You can of course still use WSGI
components, but your application will not be able to run on a server
that doesn't provide your async framework's API.
>It is really so hard to implement WSGI 1.0 and to write middlewares for it?
Absolutely. Most of the time I see someone post example middleware
code, it is not WSGI compliant in some fashion.
>I think that WSGI 2.0 should simply correct some problems in WSGI 1.0,
The single biggest problem in WSGI 1.0 is start_response() and
write(). They were hacks to support legacy applications and frameworks.
>It's very unfortunate that the WSGI implementation in Twisted just uses
>threads instead of doing some experimentation.
You're making the assumption that no experimentation was done. Check
the Web-SIG archives from three years ago and see the discussions
about async APIs.
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