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https://issues.apache.org/jira/browse/SCXML-217?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14187240#comment-14187240
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Johannes Neuber commented on SCXML-217:
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Thank you for the quick reply! I think <transition type="internal" .../> is
exactly what I was looking for.
But nevertheless I'm a little bit confused now, because I didn't expected this
behavior. And I didn't found any examples using "internal transitions".
In my imagination it was pretty clear that if the source of the transition "e3"
is "S1" and it's target is "S13", "S1" wouldn't need to be left/exited to reach
"S13" (because S13 is direct child of S1). I thought this should be the default
behavior.
> <parallel> doesn't work correctly (according to SCXML2 W3C Spec)
> ----------------------------------------------------------------
>
> Key: SCXML-217
> URL: https://issues.apache.org/jira/browse/SCXML-217
> Project: Commons SCXML
> Issue Type: Bug
> Affects Versions: 2.0
> Environment: java version "1.7.0_60"
> Java(TM) SE Runtime Environment (build 1.7.0_60-b19)
> Java HotSpot(TM) 64-Bit Server VM (build 24.60-b09, mixed mode)
> Windows 7
> Reporter: Johannes Neuber
> Priority: Blocker
>
> W3C Specification says: {quote}<parallel>: „... Transitions *within the
> individual child elements operate normally*. However *whenever a transition
> is taken with a target outside the <parallel> element, the <parallel> element
> and all of its child elements are exited* and the corresponding <onexit> …“
> {quote}
> In the current implementation (I tested commons-SCXML2-2.0-SNAPSHOT.jar from
> the 13th of September) it happens (reproducible) that the <parallel> region
> is exited also if the target of a <transition> is within the <parallel>
> region. That’s a real blocker, because it makes the usage <parallel> elements
> almost impossible in real/big projects:
> {code:xml}
> <scxml xmlns="http://www.w3.org/2005/07/scxml"; version="1.0"
> xmlns:cs="http://commons.apache.org/scxml"; initial="p">
> <parallel id="p">
> <transition event="done.state.p" target="end" />
> <state id="S1" initial="S11">
> <state id="S11">
> <transition event="e4" target="S12" />
> </state>
> **<transition event="e3" target="S13" />**
> <state id="S12">
> <transition event="e1" target="S1Final" />
> </state>
> <state id="S13">
> <transition event="e1" target="S1Final" />
> </state>
> <final id="S1Final" />
> </state>
>
> <state id="S2" initial="S21">
> <state id="S21">
> <transition event="e1" target="S22" />
> </state>
> <state id="S22">
> <transition event="e2" target="S2Final"/>
> </state>
> <final id="S2Final" />
> </state>
> </parallel>
> <final id="end"/>
> </scxml>
> {code}
> Output using org.apache.commons.scxml2.test.StandaloneUtils:
> {code}
> 0 [main] INFO org.apache.commons.scxml2.env.SimpleSCXMLListener - enter
> /p
> 1 [main] INFO org.apache.commons.scxml2.env.SimpleSCXMLListener - enter
> /p/S1
> 1 [main] INFO org.apache.commons.scxml2.env.SimpleSCXMLListener - enter
> /p/S1/S11
> 1 [main] INFO org.apache.commons.scxml2.env.SimpleSCXMLListener - enter
> /p/S2
> 1 [main] INFO org.apache.commons.scxml2.env.SimpleSCXMLListener - enter
> /p/S2/S21
> {code}
> Ok so far!
> Firing Event *{color:green}e1{color}*
> {code}
> 43257 [main] INFO org.apache.commons.scxml2.env.SimpleSCXMLListener - exit
> /p/S2/S21
> 43257 [main] INFO org.apache.commons.scxml2.env.SimpleSCXMLListener -
> transition (event = e1, cond = null, from = /p/S2/S21, to = /p/S2/S22)
> 43257 [main] INFO org.apache.commons.scxml2.env.SimpleSCXMLListener - enter
> /p/S2/S22
> {code}
> Ok so far ...
> Now firing Firing Event *{color:green}e3{color}* (Note */p/S1/S11* and
> */p/S2/S22* *are* the *active* states now)
> {code}
> 119890 [main] INFO org.apache.commons.scxml2.env.SimpleSCXMLListener - exit
> /p/S2/S22
> 119890 [main] INFO org.apache.commons.scxml2.env.SimpleSCXMLListener - exit
> /p/S2
> 119890 [main] INFO org.apache.commons.scxml2.env.SimpleSCXMLListener - exit
> /p/S1/S11
> 119890 [main] INFO org.apache.commons.scxml2.env.SimpleSCXMLListener - exit
> /p/S1
> 119891 [main] INFO org.apache.commons.scxml2.env.SimpleSCXMLListener - exit
> /p
> 119891 [main] INFO org.apache.commons.scxml2.env.SimpleSCXMLListener -
> transition (event = e3, cond = null, from = /p/S1, to = /p/S1/S13)
> 119891 [main] INFO org.apache.commons.scxml2.env.SimpleSCXMLListener -
> enter /p
> 119891 [main] INFO org.apache.commons.scxml2.env.SimpleSCXMLListener -
> enter /p/S1
> 119891 [main] INFO org.apache.commons.scxml2.env.SimpleSCXMLListener -
> enter /p/S1/S13
> 119891 [main] INFO org.apache.commons.scxml2.env.SimpleSCXMLListener -
> enter /p/S2
> 119891 [main] INFO org.apache.commons.scxml2.env.SimpleSCXMLListener -
> enter /p/S2/S21
> {code}
> *{color:red}That's not correct!{color}*
> If the event *e3* is triggered, all <parallel> regions are left! Afterwards
> state */p/S1/S13* is correctly activated, but unfortunately the other
> <parallel> region *S2* is changing to it's <initial> state */p/S2/S21*!
> If transition *e3* had a target outside the <parallel> element, this behavior
> would have been correct. But it doesn't have! It's target is *S13* which is
> definitely inside the <parallel> element *p*!
> After triggering Event *e3* the state machine must be in the following active
> states: */p/S1/S13* and *p/S2/S22*. And *only* the <onexit> handler of *S21*
> has to be executed and the <onentry> handler of state *S13*. Nothing more ...
> If I change the specifications like this, everything works correctly. But
> that'S not what I/we want:
> {code:xml}
> <transition event="done.state.p" target="end" />
> <state id="S1" initial="S11">
> <state id="S11">
> <transition event="e4" target="S12" />
> <transition event="e3" target="S13" />
> </state>
> <state id="S12">
> <transition event="e1" target="S1Final" />
> </state>
> <state id="S13">
> <transition event="e1" target="S1Final" />
> </state>
> <final id="S1Final" />
> </state>
> {code}
> Do you have an idea for a quick fix?
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