On 6/28/07, Nestor Urquiza <[EMAIL PROTECTED]> wrote:

Not to mention that some custom actions could have to be evaluated before 
knowing which transition will apply.

It might mean that some side effects could come into scene, and if they do  the 
"introspection mode" cannot be used.


Actions aren't executed unless a transition is actually followed, so
we should be OK there. However, the guard conditions on candidate
transitions would need to be evaluated, and they would need to be
side-effect free (as they should be).

In other words, the act of identifying which transition(s) should be
followed is idempotent.




----- Original Message ----
From: Rahul Akolkar <[EMAIL PROTECTED]>
To: Jakarta Commons Users List <commons-user@jakarta.apache.org>
Sent: Wednesday, June 27, 2007 11:05:54 AM
Subject: Re: [SCXML] Querying if an event would cause a transition

Please prefix the email subject with [SCXML], since this mailing list
is shared across all Commons components. I've added the prefix here.

On 6/27/07, Christopher Giblin <[EMAIL PROTECTED]> wrote:
> Hi,
> I am new to Commons SCXML.
> Is it possible to determine whether an event would result in a transition,
> without that transition occuring? Including evaluation of transition
> conditions?

While the idea is interesting, we do not have such an "introspection mode".

It wouldn't take too much effort to implement it, but:

a) Would probably increase the code smell factor a tad (if in
introspection mode, then follow transition else just report back etc.)

b) Would require some API additions that might warrant a major release.

If you don't mind sharing in this public forum, why do you need such
introspection? The SCXML specification doesn't talk about this.
Understanding that interaction pattern may or may not help better
answer the question, we will have to see :-)


> Thanks,
> chris

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