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From "Rahul Akolkar" <>
Subject Re: [SCXML] Default Transitions
Date Sat, 08 Apr 2006 05:43:36 GMT
On 4/7/06, Fasih <> wrote:
> Hi
> An action can emit multiple event, one of which can be an error. I dont want to define
an error transition for each of my states, I was going thru the SCXML specs, I couldn't locate
anything like a default transition. However, they have
> <quote>
> Thus the most narrowly scoped transition wins. The motivation for this choice becomes
clear when we remember that sequential substates are decompositions of the parent state. Thus
S112 is a refinement of S11 and S11 in turn is a refinement of S1. The innermost state thus
"knows the most" about the situation so its transitions are preferred to those in outer states,
which can be treated as defaults or fallbacks.
> </quote>
> So, to achieve a default transition, I guess defining my state engine as a substate of
a super state which has all the error transtions would work.

Thats right, you can also leverage the "src" attribute of <state> to
achieve similar results. As an example, check out the "createProfile"
state in this example (long URLs, may be fragmented):

which actually pulls in this state machine:

as the body of "createProfile" and adds a new "global" transition for
the enclosed state machine. This also has a "templating" effect where
the enclosed state machine can be reused several places with different
"decorations" around it.

> Also, another wy I was thinking of was to have an ErrorListener or StateListener to alert
me. Is that expected to use these for such kind of a thing??

Depends ;-) This post may help:


> +Fasih

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