Stackless Python/Twisted example Re: [Twisted-Python] Advice sought on application evolution

Andrew Francis andrewfr_ice at
Thu Apr 3 11:21:25 EDT 2008

Hi Don and Colleagues:

>I'll be very interested to learn more about the
>melding of the two paradigms.


>One question: I had the impression that Stackless is
>mostly an academic exercise, sort of a proof of
>concept.  Is this wrong?  How stable, portable, etc.
is Stackless at this point?  Is it a reasonable choice

>for a commercial application?

Sorry for the wait - I have been very busy. I will
probably update my blog on the weekend. Meanwhile, I
have enclosed an example of a Toy WS-BPEL processor
prototype that more or less implements the I/O parts
of WS-BPEL specification: invoke, reply, receive,
wait, event handlers, and daemons!

In the process, the programme shows all the
integration techniques in action.

The main thing I want readers to take away is how
*little* Stackless Python and Twisted are needed to
implement something complex. To me, this is what
Python is all about.

In your case Don, I try to show how layering helps
model business logic. In the example, think of the
Process and AlarmProcess belonging to the business
logic layer.

I have tried my best to strip away the WS-BPEL
specific parts to show how I integrate Stackless with
Twisted. Still the architecture is influenced by my
need to prototype. I am still experimenting.

That said, this little prototype starts up 1001
tasklets. If a web client does a HTTP GET on
the tasklet will wake up, call a web server (in my
case Apache), and return a result. Another tasklets
simply ticks.

Give me a while, and I will show another example with
process serialization (at Pycon 2008 - I demonstrated
process serialization to a few folks after my talk -
hint Twisted does not like to be pickled).

Unfortunately I have not had time to set up stress
tests. I really don't have access to large computers.

That said, the integration techniques reflect my
thinking about November/December 2007. I am eager to
find the time to try out Christopher Armstrong's
coroutine package.

If you have any questions, please don't hesitate to


You rock. That's why Blockbuster's offering you one month of Blockbuster Total Access, No Cost.
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