[Web-SIG] When must applications call the WSGI start_response callable.
jim at zope.com
Thu Dec 15 22:02:59 CET 2005
Ian Bicking wrote:
> Jim Fulton wrote:
>> Why do I want this? It appears that this would be needed to enable
>> middleware components that manage application threads. I can imagine
>> though that there aren't any existing servers that handle what I've
>> suggested correctly.
>> I do think it would be straightforward for servers to handle this
>> correctly, especially for asynchronous servers like Twisted
>> and ayncore-based servers. Perhaps this could be an optional feature
>> of the servers. Servers supporting this feature would be prepared to
>> delay response output until start_response is called. Servers unable
>> to do this would generate errors if start_response hasn't been called
>> by the time the result iterator has been constructed.
> I suppose this wouldn't be particularly bad for threaded or multiprocess
> servers either -- they use a thread/process until the request is
> completed regardless of what happens.
Exacept that it makes the implementation a bit more complex.
> I can see how it could be used to
> greater effect in an asynchronous server. However, I'd rather it not be
> optional, as most WSGI apps won't do this, and so servers won't get good
> testing on this or may just not implement it, and then some apps and
> some servers won't be compatible.
I mostly agree, except that I think this feature may only be useful for
Jim Fulton mailto:jim at zope.com Python Powered!
CTO (540) 361-1714 http://www.python.org
Zope Corporation http://www.zope.com http://www.zope.org
More information about the Web-SIG