[Twisted-Python] Synchronous calls using Twisted?

[Mike Winter]

half async/half sync is not as obscure as you may think:

www.cs.wustl.edu/~schmidt/PDF/PLoP-95.pdf

On May 17, 2012, at 12:06:04PM, Andrew Francis wrote:

> Message: 1
> Date: Thu, 17 May 2012 00:58:57 +0200
> From: Louis <spalax at gresille.org>
> Subject: [Twisted-Python] Synchronous calls using Twisted?
> To: twisted-python at twistedmatrix.com
> Message-ID: <4FB43131.2030805 at gresille.org>
> Content-Type: text/plain; charset=ISO-8859-1
> 
> >  Hello,
> >  I am writing an application, which architecture is (I hope my
> >beautiful drawing is not messed up):
> 
> >  +-------------+  +------------+  +-----------+
> >  | Core Server |---| Web Server |---| Web client|
> >  +-------------+  +------------+  +-----------+
> >...
> 
> >  Do you think Twisted is the right tool for my use case, or am I doing
> >an ugly hack to do what I want, which means I should rather use another
> >tool?
> 
> I am not sure why inline generators won't work?
> 
> Over the years, I use Stackless Python with Twisted. I use Twisted for many of the reasons you describe. For myself there is another dimension: I find that a lot of the code I write are orchestrations - that is in order to compute something, I have to make a few network calls sequentially. 
> 
>  I use a technique that Christopher Armstrong (what happened to him?) called a blockOn. For the sake of being academic (roll your eyes here),  this is an example of an obscure design pattern called "Half-sync/Half-async."
> 
> Essentially one does the following:
> 
> def blockOn(deferred): 
>     ch = stackless.channel() 
>     def cb(result): 
>         ch.send(result) 
>     deferred.addBoth(cb) 
>     return ch.receive() 
> 
> Of course, there is a bit more, like the Twisted reactor is running in its own tasklet. But this has the effect of nicely allowing one to use Twisted in a synchronous fashion. If you don't feel like installing Stackless Python, then you can use stackless.py (not the new version that uses continuations) with the greenlet package.
> 
> Here is a link to a complete example
> 
> http://andrewfr.wordpress.com/2011/11/30/the-santa-claus-problem-with-join-patterns/
> 
> Cheers,
> Andrew
> 
> 
> 
> 
> _______________________________________________
> Twisted-Python mailing list
> Twisted-Python at twistedmatrix.com
> http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://twistedmatrix.com/pipermail/twisted-python/attachments/20120517/d1450a60/attachment.htm