[Web-SIG] Re: Preferred set of WSGI servers

[Steve Holden]

Ian Bicking wrote:
> Peter Hunt wrote:
> 
>> Actually, I think a mod_wsgi for Apache and IIS would be one of _the_ 
>> most important things for WSGI. I think that it would search for a 
>> __wsgi__.py file (or maybe something with a better name) which would 
>> expose a WSGI application named "application" that would handle 
>> requests for the directory in which it exists. This would allow a user 
>> to simply drop a file on the webserver and have it work. It would be 
>> excellent for shared hosting solutions.
> 
> 
> Would it?  From what I can tell, mod_php is very popular in shared 
> hosts, but neither mod_python nor mod_perl are.  I don't think mod_* 
> makes it necessarily host-friendly.  But from what I can tell of 
> mod_python, it would be relatively easy to have something like .wsgi 
> files, and give them a handler that runs them as WSGI apps.
> 
> I can imagine a good setup for hosts being one based on forking per-user 
> processes, which is adaptive primarily to scale down -- e.g., a largely 
> dorman app could have 1 or even 0 processes running (at 0 it becomes 
> similar to CGI, but presumably the process would stay around for some 
> time to respond to subsequent requests).  The "scaling down" scenario I 
> often think about would be a email contact form -- one of those things 
> that has to be an app, can be implemented and deployed separately from 
> other aspects of the site, and yet it's clear waste of resources to keep 
> a process always around to respond to such requests.  Though it's 
> actually someplace where CGI would work just fine; but lets say you 
> don't want to educate the developer about when they might want to use 
> other deployment strategies (which is a rather complex discussion 
> really, that would be better avoided by providing one really good 
> strategy and telling everyone to use it).
> 
> Maybe mod_python is appropriate for that kind of situation, I'm not 
> sure.  It could also be implemented with a second, single process that 
> was developed and deployed separately from Apache.
> 
> As for IIS and ISAPI, I can't say I really know what the archicture of 
> that system is, so I don't know.  Oh, but that does remind me of another 
> WSGI server: ASP.  Though I remember vaguely this came up before and it 
> seemed infeasible because ASP didn't support anything like PATH_INFO. Oh 
> well, I can't remember now.
> 
Seems to me that mod_python isn't really suitable for a shared-hosting 
environment because of the need to restart the server when 
indirectly-imported modules are updated, a situation that I believe 
mod_python does not detect.

This would cause all other hosted sites' sessions to be forcibly 
terminated without some persistent-state mechanism that can't be 
guaranteed to be present for all sites, and of course most hosting 
companies aren't willing to have their customers say when shared-hosting 
servers are restarted.

For these reasons I've never pestered any of our service providers to 
support mod_python even though I have done quite a bit of experimental 
work with it and really quite like that environment.

regards
  Steve
-- 
Steve Holden        +1 703 861 4237  +1 800 494 3119
Holden Web LLC             http://www.holdenweb.com/
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