[Twisted-Python] Synchronous calls using Twisted?

[gelin yan]

On Fri, May 18, 2012 at 4:17 AM, Mike Winter <miwinter at cisco.com> wrote:

> half async/half sync is not as obscure as you may think:
>
> www.cs.wustl.edu/~ <http://www.cs.wustl.edu/%7E>*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
>
>
>
>
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>

Hi Andrew

    What is the advantage of using stackless with twisted?

Regards

gelin yan
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