[Twisted-Python] You guys rock

[Itamar Shtull-Trauring]

Barry A. Warsaw wrote:

> You guys have a big problem, because it was /way/ too easy to do!  How
> are you going to make the big consulting bucks? :)

It's simple:

1. Get everyone to use it.
2. ???
3. MONEY!

> Three commands and I had an nntp server with a single newsgroup that
> was featured enough to connect Mozilla to, and to point Mailman's
> gateway at and actually get messages flowing back and forth.
> Congratulations!

Thanks - can we ask you for a quote for our 1.0 press release?

> I don't know if I'm going to do much else with Twisted, but I /would/
> like to try to figure out how to use it in a Mailman functional test
> suite.  Right now I have some very ugly kludges to start up smtpd.py,
> send a message to it, and then suck the message out and compare the
> results with what I expect.  As time permits I think I'll try to see
> how easy it would be to use Twisted in the role of smtpd.py, and add
> some tests for news as well as mail.
> 
> The main issue is that unittest must be able to fire off the server,
> and extract information from it once the message has been propagated.
> My current test is pretty kludgy, but I'll spare you the asyncgore
> (sic).  What would be ideal would be to be able to create a Twisted
> service but don't start it, send a message via Mailman machinery, then
> start the server and block on reading that message back from Twisted
> (with a timeout).  I'd run Twisted with both an SMTP and NNTP server.
> Has anybody else thought about using Twisted in a unit or functional
> test situation?

Well, if the Twisted server is in the same process (you can run it in a 
different thread) you have two alternatives:

reactor.listenTCP(8025, myFactory)
# we don't call reactor.run() here, instead we do
while testIsntDone:
     reactor.iterate() # do a single iteration of the event loop

Or:

reactor.listenTCP(8025, myFactory)
reactor.run()
# when test is done it can call reactor.crash() to stop the event loop,
# which unlike reactor.stop() still allows us to run() again


In both cases you can use reactor.callLater() for a timoeut. We do both in 
our unit tests (twisted.test) package, so you can find some examples there.

If you want to run Twisted in a different process, you may want to look at 
how admin/accepttests does it. Basically you make a python script that has a 
twisted.internet.app.Application instance called "application" at module 
level, use the twistd command to run it (twistd -y myscript.py), and then 
"kill `cat twistd.pid`" to shutdown the server. If you want to communicate 
with it while its running xml-rpc would probably work nicely 
(twisted.web.xmlrpc and see the example in doc/examples/).