Le vendredi 04 f�vrier 2005 � 15:06 +0100, Erik Bruchez a �crit :
> Eric van der Vlist wrote:
> 
> > I have some questions about the scheduler processor:
> > 
> >       * What's happening when synchronized is set to false and another
> >         task with the same name is already running? 
> 
> >       * Is the previous instance of the task stopped or can several
> >         instances of a same task run at the same time?
> 
> It should just run in parallel. I am saying "should" quickly looking at 
> the code (I didn't write it). That's also the behavior I would expect.
> 
> On the other hand, if "synchronized" is set to true, the task simply 
> doesn't run, which is not quite what I would call synchronization.

No ;-) ...

> >       * What's happening when an exception is raised in a task? 
> 
> It's just going to fail.

If the task has been scheduled for repeated executions, would that
completely stop the task or just the current execution?

> >       * Is this exception handling configurable?
> 
> Not at the moment. I think this should be best handled by exceptions in XPL.

Yes.

> >       * Why are the inputs of the task embedded in the config input?
> >         Wouldn't that make more sense to define them as... inputs?
> 
> Because there are two distinct steps:
> 
> o Configuring the scheduler, which may occur, for example when the 
> application context is started.
> 
> o Running the task, which may happen at a much later time, and in a 
> different context.
> 
> When the task runs, it should *then* read its inputs, as opposed to 
> using inputs available when the scheduler was initialized. This is also 
> consistent with the way the main processor and error processor are 
> configured in OPS.

Hmmm... yes of course, that makes sense.

> >       * Is that an error to try to stop a task that isn't running?
> 
> Looking at the code, it looks like not. Which is also the correct 
> behavior I think, for synchronization reasons (e.g. the task may have 
> just terminated on its own).
> 
> >       * What happens exactly when a command is stopped? 
> 
> The task runs to completion. "If the task has been scheduled for 
> one-time execution and has not yet run, or has not yet been scheduled, 
> it will never run. If the task has been scheduled for repeated 
> execution, it will never run again. (If the task is running when this 
> call occurs, the task will run to completion, but will never run again.)"

OK. So this is more "no more repetitions" than "stop the task".

> >       * Are there any risk that a task is stopped in the middle of a
> >         processing?
> 
> No.
> 
> >       * If yes, shouldn't it be possible to define transaction like
> >         sections in a pipeline which should be completed before a task
> >         can be stopped?
> 
> See above.
> 
> >       * Wouldn't it be fine if the scheduler processor had a third
> >         command that outputs the list of running tasks?
> 
> Maybe a list of defined tasks and their current status.
> 
> http://sourceforge.net/tracker/index.php?func=detail&aid=1116191&group_id=116683&atid=675663

I have yet another question :-) ...

Is there a way to automatically start a task when the server starts
(other than sleeping for a while and sending a HTTP request through wget
or lynx)?

Thanks!

Eric (wondering if he'd better use a cron and/or the scheduler to
periodically retrieve information from external sources such as
Wikipedia).

-- 
Carnet web :
           http://eric.van-der-vlist.com/blog?t=category&a=Fran%C3%A7ais
------------------------------------------------------------------------
Eric van der Vlist       http://xmlfr.org            http://dyomedea.com
(ISO) RELAX NG   ISBN:0-596-00421-4 http://oreilly.com/catalog/relax
(W3C) XML Schema ISBN:0-596-00252-1 http://oreilly.com/catalog/xmlschema
------------------------------------------------------------------------



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