On Fri, 30 Mar 2007 12:01:27 +0100, Matthew Glubb <matt@zgroupplc.com> wrote:
Hi All,
I am new to twisted and python. I am evaluating the possibility of using it for an application that I am writing. The framework looks very comprehensive (I am also enjoying the python language :) but I have some questions regarding deferred objects and the twisted web server itself.
My application essentially comprises the following:
1. HTTP request is received by the server. 2. Server creates a listening socket on an arbitrary port and waits for n seconds for incoming data 3. Data (or timeout message) is returned to the client by way of the HTTP response.
[snip]
I was wondering whether it is feasible to use the twisted framework for this application. I have been playing with the framework and I can't see a way to service what are essentially thousands of requests that perform blocking operations simultaneously. I have noted the twisted documentation on threads but I was hoping, for the sake of my sanity, that I might be able to manage this using an asynchronous approach. Essentially, what I think I am looking for is a waitFor() on a deferred callback.
There's no way to block until an event occurs. Blocking would prevent the reactor from noticing the event or informing you about it. :) Fortunately you don't need to resort to threads, either. The conventional way to do this would be to write a function which sets up the listening port and returns a Deferred which will eventually be called back with the result (presumably the data which some client will eventually send to it). Then, using reactor.callLater, set up a timed call which will tear down the listening port after the timeout has expired and errback the Deferred to indicate no data arrived within the timeout period. Actually, that's the only way to do it. :P The conventional implementation would be to do this using explicit callback functions in the style you may have noticed in many Twisted examples. There are other ways which allow you to write code in a different style which some people prefer, but it's just a difference in spelling, the same thing is happening underneath.
As an aside, is it possible to compile platform specific python applications as small binaries? Or does the interpreter (is it required?) mean the memory consumption is prohibitive?
Generally the only thing that's possible is to wrap up the whole application with the whole interpreter and some subset of the standard library in an executable. This doesn't sound much like what you're after, though. Jean-Paul