Hi Anthony,

sorry for the late reply.

On 3/23/06, Anthony Bigbee <[EMAIL PROTECTED]> wrote:
>
> I think I may be confusing workitems with workflows.  Let me try to
> explain my need and see if that helps.
>
> Pursuant to the previous cron question, I'm trying to have an AP
> periodically poll an external database.

APs are 'workitem triggered'. Of course you could have a piece of code
polling the DB and 'launching' a process when there is stuff to
happen.

Or the AP could be 'not blocking', it could be triggered by a cron,
and when there is nothing needing to happen, the workitem passed by
the cron to the AP, would be discarded.

> If the database indicates stuff needs to happen *and* the next AP is
> not already working on N workitems or workflows, then either launch a
> new workflow with the 'next AP' being the first participant in that
> workflow or forward the workitem to the next AP.  I'm looking for a
> way to throttle how many workitems the next AP (the one that actually
> does some processing) receives at any given time.

You could do a 'round-robin', the DB polling AP always sending a wi to
another 'next participant'.

The APs could also communicate with each other (especially if they are
instantiated 'once' and living in the same APRE).

APs are 'initted' with an ApplicationContext, we could maybe bind each
AP instantiated once in the ApplicationContext so that they can very
easily 'see' each other. (I'll think about this).

> I'm trying to figure out if the cron-based participant (system cron or
> openwfe 'cron') should be part of a workflow definition or not (i.e.
> the first participant).  Chapter 12 confuses me and I'm not sure how
> to relate a workflow definition using concurrent and sequential
> definitions and process definitions at the engine level and apre APs.

Maybe you could have a look at that :
http://web.openwfe.org/display/openwfe/Process+Definition+Examples+3

You should perhaps build up some small examples of cron, playing
around with the basic Alice, Bob and Charly participants. Maybe you'll
then have suggestions for or pieces of documentation.

Feel free to ask questions about chapter 12, in order to make it
easier for everybody to understand.

--
John Mettraux   -///-   http://jmettraux.openwfe.org


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