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From "Rahul Akolkar" <>
Subject Re: [SCXML] Event types
Date Tue, 22 May 2007 02:58:29 GMT
On 5/21/07, Nestor Urquiza <> wrote:
> Hi Rahul,
> Talking about this I do not know if I posted about it before ( lazy now to search in
the archives ) but at some point I ( at least ) thought about a special event let us say "app.error"
that I was hoping to use from a custom action for example to provide an "exception" mechanism.
> In a glance imagine your custom action needs to stop the normal course of your SCXML
code. I was hoping to use the type ERROR to define a special event called "app.error" that
would be included in the transition element to specify where to go when an unexpected exception
> My guess a while ago was that it would be great to make commons-SCXML "exception aware"
meaning that if for some reason an event of ERROR type is raised the complete state machine
would stop processing the current logic triggerred by a regular event and would then proceed
to the transitions to move the FSM to a state corresponding to the error event transition
> Makes sense?

Yes, users can leverage the event types (either existing or new /
user-defined) to have application-specific semantics, as you indicate
above. However, Commons SCXML itself does not use the type


> Thanks,
> -Nestor
> ----- Original Message ----
> From: Rahul Akolkar <>
> To: Jakarta Commons Users List <>
> Sent: Monday, May 21, 2007 1:06:18 PM
> Subject: Re: [SCXML] Event types
> On 5/20/07, Hanh-Missi Tran <> wrote:
> > Hi
> >
> > A TriggerEvent object is associated with a type (CALL_EVENT,
> > SIGNAL_EVENT, ..) but   I don't know what they are used for. I look in
> > the source code but whenever an event is handled, its type is not used
> > (I'm wrong ?). So can someone tell me what they may be used for ?
> >
> <snip/>
> You are correct, the type information is not used.
> One of the intents of providing that was to use it as potential basis
> for priority (for example, a CHANGE_EVENT, since its usually a derived
> event, would have a lower priority etc.) -- but that was never
> realized in code (or spec).
> -Rahul

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