On 04/10/2007, Phillip J. Eby <[EMAIL PROTECTED]> wrote: > At 09:52 PM 10/3/2007 +0200, Manlio Perillo wrote: > >Phillip J. Eby ha scritto: > > > [...] > > > > > > Now that I understand what this is for, I can explain why a WSGI > > > extension is not necessary to provide this feature. In a compliant WSGI > > > gateway, yielding an empty string from 'a-generator' is sufficient to > > > "flush" the WSGI pipeline. > > > > > > >But the WSGI pipeline should already be flushed for every string > >yielded, right? > > > >An interesting "extension" for an asynchronous WSGI gateway is to > >"suspend" the iteration when an empty string is returned, creating a > >timer that fires after 0 milliseconds (in Twisted, this is the same as > >callLater(0, ...)) > > > > > I suggest that you read this section of the spec more carefully: > > > > > > http://www.python.org/dev/peps/pep-0333/#buffering-and-streaming > > > > > > >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. :)
The actual wording of the PEP does though suggest that if one calls write() returned from start_response() that one would flush headers. Ie., the requirement for a non-empty string is really only mentioned in reference to value returned from iterable and not in relation to empty data string passed to write(). I am not sure I understand the importance of being strict and not flushing headers until the first non-empty content data block. Was there a specific reasoning or use case behind saying that? Graham _______________________________________________ Web-SIG mailing list Web-SIG@python.org Web SIG: http://www.python.org/sigs/web-sig Unsubscribe: http://mail.python.org/mailman/options/web-sig/archive%40mail-archive.com
