Execution state persistence for workflow application

Christian Tismer tismer at tismer.com
Mon Dec 8 23:37:59 EST 2003


Alan Kennedy wrote:

> [Serge Orlov]
> 
>>>The problem is that one day you will
>>>have to upgrade your program and your last dumpexec won't be
>>>compatible with your next loadexec(). You will have to separate
>>>code from data to do it. So it means execution persistence is not
>>>enough for real life use. Why not just use data persistence alone?
> 
> 
> [Paolo Losi]
> 
>>In fact data persistence is not sufficient to stop and resume scripts
>>in case, for example, system reboot.
>>I do want my workflow scripts to resume exactly (and with the same
>>globals/locals setup) where they left...
>>
>>The real alternative would be to define a new script language
>>with standard constructs (for, while,...) but again... i don't want
>>to reinvent the wheel.
>>
>>I do not seen execution persistence as an alternative to data
>>persistence: I would need both.
> 
> 
> You might want to investigate Stackless python, an excellent research
> work which can save and resume execution state, to some degree. Try
> the following google query

Here is a small example that I wrote last weekend for Zope.
It looks very simple, it lets you run 10 answers
*from* the web server against the client in a loop,
with no visible call-backs.
It *is* a server loop, but ti's obvious that there
cannot be a simple loop, since the server freezes
until the next request come in.
Well, it looks simple, but here is the real power!

http://www.centera.de/tismer/stackless/zope_demo/runDemo

Will try to finish this and publish, soon -- chris

-- 
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