PyISAPIe versus HttpModules in IIS7

[geographika]

Hi list,

I'm wondering if anyone has any thoughts on the future of ISAPI, and
by association with PyISAPIe due to the new HttpModules in IIS7.

As ISAPI is now a legacy API, can we assume MS will support it for the
foreseeable future?
Does improved resource management in the HttpModules (not that there
is one for running Python as yet), give performance increases over
ISAPI, or will ISAPI still be faster?

Any thoughts appreciated.

Seth G.

http://geographika.co.uk

[Phillip]

Hi Seth,

That's a pretty good question. I'm not too familiar with HttpModule
development just yet, so I can't say if PyISAPIe will evolve towards
that in the future or not- I guess it depends on what happens to
ISAPI. I can say that ISAPI, in its most simple representation, is
ridiculously simple and fast. I can't see why it'd become entirely
obsolete, especially for extensions written in C/C++.

I think ISAPI will be faster than other solutions for PyISAPIe for a
long time because any performance cost incurred right now is coming
directly from Python - e.g. the GIL and other things. This is because
PyISAPIe is very "close to the metal" - 99.99% of web app execution
time will happen in the Python interpreter. Secondary I/O like
database connections might benefit from better web server integration
(and maybe resources provided by HttModule development) but something
like that would be a long ways off. However, if there are advanced
server-based caching mechanisms (ala memcached) they'd probably be
best exploited with newer extension APIs. I'll definitely look into
this sometime in the future.

So, in general, things are about as fast as they're going to get for
now- and it's generally faster than other similar solutions so at
least there's something to appreciate about its current state.

Cheers,

Phillip

[Seth]

Thanks Philip for the reply. Interesting to read about the GIL leading
to further links to Stackless Python, and PyProcessing.
It looks like ISAPI is definitely the second choice for new HTTP
modules by reading IIS7 docs, but ISAPI will be supported for a long
time to come.
Glad to hear PyISAPIe remains the fastest (and one of the simplest)
ways to get Python up and running on a Windows server.