[Web-SIG] Request for Comments on upcoming WSGI Changes

[Armin Ronacher]

Hello everybody,

Thanks to Graham Dumpleton and Robert Brewer there is some serious
progress on WSGI currently.  I proposed a roadmap with some PEP changes
now that need some input.

Summary:

  WSGI 1.0       stays the same as PEP 0333 currently is
  WSGI 1.1       becomes what Ian and I added to PEP 0333
  WSGI 2.0       becomes a unicode powered version of WSGI 1.1
  WSGI 3.0       becomes WSGI 2.0 just without start_response

  WSGI 1.0 and 1.1 are byte based and nearly impossible to use on Python
  3 because of changes in the standard library that no longer work with
  a byte-only approach.


The PEPs themselves are here: http://bitbucket.org/ianb/wsgi-peps/
Neither the wording not the changes in there are anywhere near final.


Graham wrote down two questions he wants every major framework developer
to be answered.  These should guide the way to new WSGI standards:

1. Do we keep bytes everywhere forever in Python 2.X, or try to
   introduce unicode there at all to at least mirror what changes might
   be made to make WSGI workable in Python 3.X?

2. Do we skip WSGI 1.X completely for Python 3.X and go straight to
   WSGI 2.0 for Python 3.X?

I added a new question I think should be asked too:

3. Do we skip WSGI 2.0 as specified in the PEP and go straight to
   WSGI 3.0 and drop start_response?


The following things became pretty clear when playing around with
various specifications on Python 3:

-  Python 3 no longer implicitly converts between unicode and byte
   strings.  This covers comparisons, the regular expression engine,
   all string functions and many modules in the stdlib.

-  The Python 3 stdlib radically moved to unicode for non unicode things
   as well (the http servers, http clients, url handling etc.)

-  A byte only version of WSGI appears unrealistic on Python 3 because
   it would require server and middleware implementors to reimplement
   parts of the standard library to work on bytes again.

-  unicode support can be added for WSGI on both Python 2.x and Python
   3.x without removing functionality.  Browsers are already doing
   a similar encoding trick as proposed by Graham Dumpleton to handle
   URLs.

-  Python 2.x already accepts unicode strings for many things such as
   URL handling thanks to the fact that unicode and byte strings are
   surprisingly interchangeable.

-  cgi.FieldStorage and some other parts is now totally broken on
   Python 3 and should no longer be used in 3.0 and 3.1 because it
   reads the response body into memory.  This currently affects
   WebOb, Pylons and TurboGears.


I sent this mail to every major framework / WSGI implementor so that we
get input even if you're missing the discussion on web-sig.


Regards,
Armin