Re: [wsbpel] Comments on Event Handlers

[Ram Jeyaraman <Ram.Jeyaraman@Sun.COM>]

> We have used three different examples for designing event handlers:
> 
> (1) Provide the capability for requestors to obtain some information
> relative to the current execution of a process instance (query capability).
> 
> (2) Provide the capability for requestors to modify the current processing
> of a process instance, such as terminating the process instance.
> 
> (3) Provide the capability to perform a certain action at a certain time,
> such as informing somebody about the business process.

Dieter, is it be possible to setup periodic alarms? For example, setup a 
periodic alarm / timer, which executes an onAlarm activity each time the 
interrupt happens.

While the current spec allows specification of several alarm events per scope, 
there does not seem to be a provision for specifying periodicity for a 
particular alarm event.

One can conceive of a periodic alarm associated with the top-level process 
scope,  that does repetitive periodic activities, for example, process state 
monitoring, etc.

One possible way to setup periodic alarms is to extend the onAlarm definition 
to include an attribute "repeat", as follows:

<eventHandlers>?
    <onMessage ...>* ... </onMessage>
    <onAlarm for="duration-expr"? until="deadline-expr"? repeat="bool-expr"?>*
        activity
    </onAlarm>
</eventHandlers>

Another possible way, perhaps, may be to use an empty dummy pick construct with 
an onAlarm activity, placed within a while loop. This may necessitate the use 
of a flow construct, in order to place the while loop as a concurrent activity, 
within the parent scope. Or even a wait construct within a while loop. thanks.