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Posted to user@commons.apache.org by Bill Herring <bh...@openmethods.com> on 2010/01/08 17:25:31 UTC
[SCXML] Parallel parent states resetting to initial substates?
I'm working with a state model with two parallel states that each have
substates:
<parallel id="channel">
<state id="agent_status" initial="ready">
<transition event="parent.goReady" target="ready"/>
<transition event="parent.goNotReady" target="not_ready"/>
<state id="ready">
<transition event="goNotReady" target="not_ready"/>
</state>
<state id="not_ready">
<transition event="goReady" target="ready"/>
</state>
</state>
<state id="channel_status" initial="off_call">
<transition event="parent.dial" target="on_call" />
<transition event="parent.hangup" target="off_call" />
<state id="off_call">
<transition event="dial" target="on_call" />
</state>
<state id="on_call">
<transition event="hangup" target="off_call" />
</state>
</state>
</parallel>
When I trigger transitions with the "leaf events" (goNotReady,
goReady, dial, and hangup) everything works as I would expect - the
two parallel states transition between substates independently.
However, if I trigger transitions using the "parent
events" (parent.X), the transition occurs in the one parallel substate
and the other parallel substate apparently "resets" to its initial
state. As a concrete example, if I trigger "parent.goNotReady"
followed by "parent.dial" I end up in "on_call" and "ready" (vs.
"on_call" and "not_ready", which I would be in if I has used
"goNotReady" and "dial" instead).
Is this a feature or a bug? Is there a way to get the same behavior
in both cases? I realize that in this trivial example there's no real
advantage to putting the transitions in parent states, but I have a
much more complex state model where I want to put "catch all"
transitions in parent states and this behavior is stopping me from
doing that.
Thanks,
Bill
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Re: [SCXML] Parallel parent states resetting to initial substates?
Posted by Rahul Akolkar <ra...@gmail.com>.
On Fri, Jan 8, 2010 at 6:37 PM, Bill Herring <bh...@openmethods.com> wrote:
> OK, I found that it is indeed a feature (Section 3.3.3 of the SCXML spec),
<snip/>
Yup, followed transition's parent state will always be exited (and if
its the base of an orthogonal region, that means all other orthogonal
region siblings will have to be exited too, given the semantics of
<parallel>).
> but I still need the behavior I describe in my original email. In an
> attempt to fix the problem, I added history states to the two parallel
> parent states, like this:
>
> <parallel id="open_channel">
> <state id="agent_status">
> <initial>
> <transition target="resume_agent_status"/>
> </initial>
> <transition event="tester.Pready" target="ready"/>
> <transition event="tester.PnotReady" target="not_ready"/>
> <state id="ready">
> <transition event="tester.notReady"
> target="not_ready"/>
> </state>
> <state id="not_ready">
> <transition event="tester.ready" target="ready"/>
> </state>
> <history id="resume_agent_status" type="deep">
> <transition target="ready"/>
> </history>
> </state>
> <state id="channel_status">
> <initial>
> <transition target="resume_channel_status"/>
> </initial>
> <transition event="tester.Pdial" target="on_call" />
> <transition event="tester.Phangup" target="off_call" />
> <state id="off_call">
> <transition event="tester.dial" target="on_call" />
>
> </state>
> <state id="on_call">
> <transition event="tester.hangup" target="off_call"
> />
> </state>
> <history id="resume_channel_status" type="deep">
> <transition target="off_call"/>
> </history>
> </state>
> </parallel>
>
> However, the result appears to be similar but with some additional strange
> behavior if I transition to a state I'm already in - I suspect the
> transitions and histories are conflicting with each other. (?)
>
> Still wondering if there's any way to use "catch-all" transitions in parent
> states when the parent states are parallel.
>
<snap/>
Add an intermediate <state> that prevents the exit from the orthogonal region.
So, instead of this pattern:
<parallel id="par">
<state id="region1">
<initial>
<transition target="foo"/>
</initial>
<transition event="trigger" target="bar"/>
<!-- foo, bar and other content -->
</state>
<!-- other regions -->
</parallel>
use the following pattern instead:
<parallel id="par">
<state id="region1">
<initial>
<transition target="intermediate"/>
</initial>
<!-- the following contains content of region1 before -->
<state id="intermediate">
<initial>
<transition target="foo"/>
</initial>
<transition event="trigger" target="bar"/>
<!-- foo, bar and other content -->
</state>
</state>
<!-- other regions -->
</parallel>
-Rahul
> - Bill
>
>
> On Jan 8, 2010, at 10:25 AM, Bill Herring wrote:
>
>> I'm working with a state model with two parallel states that each have
>> substates:
>>
>> <parallel id="channel">
>> <state id="agent_status" initial="ready">
>> <transition event="parent.goReady" target="ready"/>
>> <transition event="parent.goNotReady"
>> target="not_ready"/>
>> <state id="ready">
>> <transition event="goNotReady" target="not_ready"/>
>> </state>
>> <state id="not_ready">
>> <transition event="goReady" target="ready"/>
>> </state>
>> </state>
>>
>> <state id="channel_status" initial="off_call">
>> <transition event="parent.dial" target="on_call" />
>> <transition event="parent.hangup" target="off_call" />
>> <state id="off_call">
>> <transition event="dial" target="on_call" />
>> </state>
>> <state id="on_call">
>> <transition event="hangup" target="off_call" />
>> </state>
>> </state>
>> </parallel>
>>
>> When I trigger transitions with the "leaf events" (goNotReady, goReady,
>> dial, and hangup) everything works as I would expect - the two parallel
>> states transition between substates independently. However, if I trigger
>> transitions using the "parent events" (parent.X), the transition occurs in
>> the one parallel substate and the other parallel substate apparently
>> "resets" to its initial state. As a concrete example, if I trigger
>> "parent.goNotReady" followed by "parent.dial" I end up in "on_call" and
>> "ready" (vs. "on_call" and "not_ready", which I would be in if I has used
>> "goNotReady" and "dial" instead).
>>
>> Is this a feature or a bug? Is there a way to get the same behavior in
>> both cases? I realize that in this trivial example there's no real
>> advantage to putting the transitions in parent states, but I have a much
>> more complex state model where I want to put "catch all" transitions in
>> parent states and this behavior is stopping me from doing that.
>>
>> Thanks,
>> Bill
>>
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Re: [SCXML] Parallel parent states resetting to initial substates?
Posted by Bill Herring <bh...@openmethods.com>.
OK, I found that it is indeed a feature (Section 3.3.3 of the SCXML
spec), but I still need the behavior I describe in my original email.
In an attempt to fix the problem, I added history states to the two
parallel parent states, like this:
<parallel id="open_channel">
<state id="agent_status">
<initial>
<transition target="resume_agent_status"/>
</initial>
<transition event="tester.Pready" target="ready"/>
<transition event="tester.PnotReady" target="not_ready"/>
<state id="ready">
<transition event="tester.notReady" target="not_ready"/>
</state>
<state id="not_ready">
<transition event="tester.ready" target="ready"/>
</state>
<history id="resume_agent_status" type="deep">
<transition target="ready"/>
</history>
</state>
<state id="channel_status">
<initial>
<transition target="resume_channel_status"/>
</initial>
<transition event="tester.Pdial" target="on_call" />
<transition event="tester.Phangup" target="off_call" />
<state id="off_call">
<transition event="tester.dial" target="on_call" />
</state>
<state id="on_call">
<transition event="tester.hangup" target="off_call" />
</state>
<history id="resume_channel_status" type="deep">
<transition target="off_call"/>
</history>
</state>
</parallel>
However, the result appears to be similar but with some additional
strange behavior if I transition to a state I'm already in - I suspect
the transitions and histories are conflicting with each other. (?)
Still wondering if there's any way to use "catch-all" transitions in
parent states when the parent states are parallel.
- Bill
On Jan 8, 2010, at 10:25 AM, Bill Herring wrote:
> I'm working with a state model with two parallel states that each
> have substates:
>
> <parallel id="channel">
> <state id="agent_status" initial="ready">
> <transition event="parent.goReady" target="ready"/>
> <transition event="parent.goNotReady" target="not_ready"/>
> <state id="ready">
> <transition event="goNotReady" target="not_ready"/>
> </state>
> <state id="not_ready">
> <transition event="goReady" target="ready"/>
> </state>
> </state>
>
> <state id="channel_status" initial="off_call">
> <transition event="parent.dial" target="on_call" />
> <transition event="parent.hangup" target="off_call" />
> <state id="off_call">
> <transition event="dial" target="on_call" />
> </state>
> <state id="on_call">
> <transition event="hangup" target="off_call" />
> </state>
> </state>
> </parallel>
>
> When I trigger transitions with the "leaf events" (goNotReady,
> goReady, dial, and hangup) everything works as I would expect - the
> two parallel states transition between substates independently.
> However, if I trigger transitions using the "parent
> events" (parent.X), the transition occurs in the one parallel
> substate and the other parallel substate apparently "resets" to its
> initial state. As a concrete example, if I trigger
> "parent.goNotReady" followed by "parent.dial" I end up in "on_call"
> and "ready" (vs. "on_call" and "not_ready", which I would be in if I
> has used "goNotReady" and "dial" instead).
>
> Is this a feature or a bug? Is there a way to get the same behavior
> in both cases? I realize that in this trivial example there's no
> real advantage to putting the transitions in parent states, but I
> have a much more complex state model where I want to put "catch all"
> transitions in parent states and this behavior is stopping me from
> doing that.
>
> Thanks,
> Bill
>
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> To unsubscribe, e-mail: user-unsubscribe@commons.apache.org
> For additional commands, e-mail: user-help@commons.apache.org
>
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