[Twisted-web] asynchronous WSGI implementation

Manlio Perillo manlio_perillo at libero.it
Fri Apr 9 07:20:10 EDT 2010

Steve Steiner (listsin) ha scritto:
> On Apr 9, 2010, at 6:32 AM, Manlio Perillo wrote:
>> Hi.
>> I have started to write an asynchronous WSGI implementation for
>> Twisted Web.
>> The code is available from a Mercurial repository:
>> http://hg.mperillo.ath.cx/twisted/twsgi/
>> The WSGI application is executed in the main Twisted thread, and the
>> application will be able to directly use Twisted features.
>> The reason I'm doing this is because I have written a WSGI
>> implementation for Nginx:
>> http://hg.mperillo.ath.cx/nginx/ngx_http_wsgi_module
> Maybe put on BitBucket?  It'd sure be easier to patch/submit pull requests/file tickets on a public repo.

I will think about it.
I don't have experience with BitBucket.  Is the issue tracker good?

>> and I would like to have a *similar* implementation written in pure
>> Python, for testing purpose.
> Will these share, or be able to use, the same demo/test code? 


The purpose is to have a Twisted and Nginx implementations with the same

> I'd love to have the option to use Twisted from a WSGI app.  

This will be possible with twsgi.
However please note that I plan to use it for testing purpose only, and
not in production (at least in the near future).

> Have you resolved the issues you brought up and have been discussing with PJE over on web-sig?  Which WSGI are you supporting? 

I will implement WSGI 1.0.

Another reason I'm writing twsgi, is that it will be more easy to
discuss about WSGI issues, having a pure Python implementation.

> This seems like a different thing than the greenlet/mako thing you were discussing over there.

The core is the same.
The WSGI implementation *must* support suspend/resume extension.

The geenlet middleware will use this extension to implement coroutine
support over a simple asynchronous WSGI implementation.

By "simple" I mean that greenlets are not used inside WSGI
implementation (since greenlets can not be used in my
ngx_http_wsgi_module, if I'm not wrong).

greenlets are not required, but without coroutines applications will be
a mess, due to generator usage.

>> By the way: it seems that the WSGI implementation in Twisted Web has
>> some bugs:
>> * close method of the application iterator is not called in case of
>>  errors
>> * _sendResponseHeaders does not check if start_response has been called
> Before someone else says it... please file bugs (helpfully with test cases) at twistedmatrix.com/trac.

Of course.
But before filling a bug report, I wanted a confirmation.

Regards  Manlio

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