On Wed, Jul 27, 2011 at 2:42 AM, Hynek Cihlar <hynek.cih...@gmail.com> wrote: > Rahul, thank you for your clear explanation. The internal transitions would > be the best solution for my use case (and also the default behavior I would > personally expect). > <snip/>
Agree it would work well for the use case below. > In terms of implementing internal transitions, I came across a thread from > James Barnett who claims to have them (and other standard features) > implemented. Here's the link, > http://apache-commons.680414.n4.nabble.com/scxml-removing-superstep-etc-td690740.html. > Would you know if there was any subsequent progress? > <snap/> IIRC, there wasn't much beyond that thread. Also, worth noting that in that post he is talking about internal events, not internal transitions. -Rahul > Thanks, > Hynek > > > > On Tue, Jul 26, 2011 at 9:14 PM, Rahul Akolkar <rahul.akol...@gmail.com>wrote: > >> On Mon, Jul 25, 2011 at 6:31 AM, Hynek Cihlar <hynek.cih...@gmail.com> >> wrote: >> > I have come across the following case, where I believe the Commons SCXML >> > behaves incorrectly. >> > >> > Assuming the following state machine configuration: >> > >> > <scxml xmlns="http://www.w3.org/2005/07/scxml"; >> > xmlns:cs="http://commons.apache.org/scxml"; >> > version="1.0" >> > initialstate="parallel"> >> > >> > <parallel id="parallel"> >> > >> > <state id="A"> >> > <initial> >> > <transition target="A.1"/> >> > </initial> >> > >> > <transition event="anEvent" target="A.2"/> >> > <transition event="anAEvent" target="A.3"/> >> > >> > <state id="A.1"/> >> > <state id="A.2"/> >> > <state id="A.3"/> >> > </state> >> > >> > <state id="B"> >> > >> > <initial> >> > <transition target="B.1"/> >> > </initial> >> > >> > <transition event="anEvent" target="B.2"/> >> > >> > <state id="B.1"/> >> > <state id="B.2"/> >> > </state> >> > >> > </parallel> >> > </scxml> >> > >> > >> > First the event "anEvent" is triggered to bring the parallel states "A" >> and >> > "B" from their initial states. Now, after triggering the event "anAEvent" >> I >> > would expect only the state of "A" to be changed. Surprisingly the event >> has >> > also effect on the "B" state, when it is brought to its initial state. >> > >> <snip/> >> >> I understand why this could be slightly surprising, but this is >> expected behavior. >> >> There are two rules of execution that combine here: >> (a) When a state machine follows a transition, it must leave the >> source state (and enter the target) >> (b) A state machine must be in all or none of the orthogonal siblings >> (or regions of a parallel) at any given time >> >> Now, with the above in mind, while processing "anAEvent" the state >> machine must leave its source state "A" which happens to be a region >> of the parallel, thereby the other region "B" must also be exited. On >> reentry into these regions, the rest states are "A2" (explicit target >> of transition) and "B1" (initial in absence of any explicit target). >> >> Clearly, this behavior may not be what you desire. Couple of ways to >> correct this and obtain the behavior you are after: >> (1) Avoid having transitions that are placed in direct child states of >> parallel, this may be done by having an intermediate "wrapper" state. >> (2) Define the transition as "internal" so source state is not exited >> in this case -- this is easier in theory but not supported by Commons >> SCXML at the moment (patches to add support welcome). >> >> -Rahul >> >> >> > Tested on the svn revision 1143657, last changed date 2011-06-07 01:13:06 >> > +0200 (Tue, 07 Jun 2011). >> > >> > I am attaching the output log from the engine execution. >> > >> > 2011-07-25 12:26:56,419 INFO >> > [org.apache.commons.scxml.env.SimpleSCXMLListener:44] : /parallel >> > 2011-07-25 12:26:56,420 INFO >> > [org.apache.commons.scxml.env.SimpleSCXMLListener:44] : /parallel/A >> > 2011-07-25 12:26:56,421 INFO >> > [org.apache.commons.scxml.env.SimpleSCXMLListener:44] : /parallel/B >> > 2011-07-25 12:26:56,421 INFO >> > [org.apache.commons.scxml.env.SimpleSCXMLListener:44] : /parallel/A/A.1 >> > 2011-07-25 12:26:56,421 INFO >> > [org.apache.commons.scxml.env.SimpleSCXMLListener:44] : /parallel/B/B.1 >> > 2011-07-25 12:26:56,425 DEBUG >> > [org.apache.commons.scxml.env.SimpleContext:165] : _eventdata = null >> > 2011-07-25 12:26:56,426 DEBUG >> > [org.apache.commons.scxml.env.SimpleContext:165] : _eventdatamap = >> > {B.entry=null, parallel.entry=null, A.1.entry=null, B.1.entry=null, >> > A.entry=null} >> > 2011-07-25 12:26:56,451 DEBUG >> > [org.apache.commons.scxml.env.SimpleContext:165] : _eventdata = null >> > 2011-07-25 12:26:56,451 DEBUG >> > [org.apache.commons.scxml.env.SimpleContext:165] : _eventdatamap = >> > {B.entry=null, parallel.entry=null, A.1.entry=null, B.1.entry=null, >> > A.entry=null} >> > 2011-07-25 12:26:56,452 DEBUG >> [org.apache.commons.scxml.SCXMLExecutor:538] : >> > Current States: [A.1, B.1] >> > 2011-07-25 12:26:56,452 DEBUG >> > [org.apache.commons.scxml.env.SimpleContext:165] : _eventdata = null >> > 2011-07-25 12:26:56,452 DEBUG >> > [org.apache.commons.scxml.env.SimpleContext:165] : _eventdatamap = >> > {anEvent=null} >> > 2011-07-25 12:26:56,459 INFO >> > [org.apache.commons.scxml.env.SimpleSCXMLListener:53] : /parallel/B/B.1 >> > 2011-07-25 12:26:56,459 INFO >> > [org.apache.commons.scxml.env.SimpleSCXMLListener:53] : /parallel/A/A.1 >> > 2011-07-25 12:26:56,459 INFO >> > [org.apache.commons.scxml.env.SimpleSCXMLListener:53] : /parallel/B >> > 2011-07-25 12:26:56,459 INFO >> > [org.apache.commons.scxml.env.SimpleSCXMLListener:53] : /parallel/A >> > 2011-07-25 12:26:56,459 INFO >> > [org.apache.commons.scxml.env.SimpleSCXMLListener:63] : transition (event >> = >> > anEvent, cond = null, from = /parallel/A, to = /parallel/A/A.2) >> > 2011-07-25 12:26:56,459 INFO >> > [org.apache.commons.scxml.env.SimpleSCXMLListener:63] : transition (event >> = >> > anEvent, cond = null, from = /parallel/B, to = /parallel/B/B.2) >> > 2011-07-25 12:26:56,460 INFO >> > [org.apache.commons.scxml.env.SimpleSCXMLListener:44] : /parallel/A >> > 2011-07-25 12:26:56,460 INFO >> > [org.apache.commons.scxml.env.SimpleSCXMLListener:44] : /parallel/B >> > 2011-07-25 12:26:56,460 INFO >> > [org.apache.commons.scxml.env.SimpleSCXMLListener:44] : /parallel/A/A.2 >> > 2011-07-25 12:26:56,460 INFO >> > [org.apache.commons.scxml.env.SimpleSCXMLListener:44] : /parallel/B/B.2 >> > 2011-07-25 12:26:56,460 DEBUG >> > [org.apache.commons.scxml.env.SimpleContext:165] : _eventdata = null >> > 2011-07-25 12:26:56,460 DEBUG >> > [org.apache.commons.scxml.env.SimpleContext:165] : _eventdatamap = >> > {B.entry=null, B.exit=null, B.2.entry=null, A.2.entry=null, >> B.1.exit=null, >> > A.exit=null, A.1.exit=null, A.entry=null} >> > 2011-07-25 12:26:56,465 DEBUG >> > [org.apache.commons.scxml.env.SimpleContext:165] : _eventdata = null >> > 2011-07-25 12:26:56,465 DEBUG >> > [org.apache.commons.scxml.env.SimpleContext:165] : _eventdatamap = >> > {B.entry=null, parallel.entry=null, A.1.entry=null, B.1.entry=null, >> > A.entry=null} >> > 2011-07-25 12:26:56,465 DEBUG >> [org.apache.commons.scxml.SCXMLExecutor:538] : >> > Current States: [B.2, A.2] >> > 2011-07-25 12:26:56,465 DEBUG >> > [org.apache.commons.scxml.env.SimpleContext:165] : _eventdata = null >> > 2011-07-25 12:26:56,465 DEBUG >> > [org.apache.commons.scxml.env.SimpleContext:165] : _eventdatamap = >> > {anAEvent=null} >> > 2011-07-25 12:26:56,469 INFO >> > [org.apache.commons.scxml.env.SimpleSCXMLListener:53] : /parallel/B/B.2 >> > 2011-07-25 12:26:56,469 INFO >> > [org.apache.commons.scxml.env.SimpleSCXMLListener:53] : /parallel/A/A.2 >> > 2011-07-25 12:26:56,469 INFO >> > [org.apache.commons.scxml.env.SimpleSCXMLListener:53] : /parallel/B >> > 2011-07-25 12:26:56,470 INFO >> > [org.apache.commons.scxml.env.SimpleSCXMLListener:53] : /parallel/A >> > 2011-07-25 12:26:56,470 INFO >> > [org.apache.commons.scxml.env.SimpleSCXMLListener:63] : transition (event >> = >> > anAEvent, cond = null, from = /parallel/A, to = /parallel/A/A.3) >> > 2011-07-25 12:26:56,470 INFO >> > [org.apache.commons.scxml.env.SimpleSCXMLListener:44] : /parallel/A >> > 2011-07-25 12:26:56,470 INFO >> > [org.apache.commons.scxml.env.SimpleSCXMLListener:44] : /parallel/B >> > 2011-07-25 12:26:56,470 INFO >> > [org.apache.commons.scxml.env.SimpleSCXMLListener:44] : /parallel/A/A.3 >> > 2011-07-25 12:26:56,470 INFO >> > [org.apache.commons.scxml.env.SimpleSCXMLListener:44] : /parallel/B/B.1 >> > 2011-07-25 12:26:56,470 DEBUG >> > [org.apache.commons.scxml.env.SimpleContext:165] : _eventdata = null >> > 2011-07-25 12:26:56,471 DEBUG >> > [org.apache.commons.scxml.env.SimpleContext:165] : _eventdatamap = >> > {B.entry=null, B.exit=null, B.2.exit=null, A.3.entry=null, A.exit=null, >> > B.1.entry=null, A.entry=null, A.2.exit=null} >> > 2011-07-25 12:26:56,473 DEBUG >> > [org.apache.commons.scxml.env.SimpleContext:165] : _eventdata = null >> > 2011-07-25 12:26:56,474 DEBUG >> > [org.apache.commons.scxml.env.SimpleContext:165] : _eventdatamap = >> > {B.entry=null, parallel.entry=null, A.1.entry=null, B.1.entry=null, >> > A.entry=null} >> > 2011-07-25 12:26:56,474 DEBUG >> [org.apache.commons.scxml.SCXMLExecutor:538] : >> > Current States: [A.3, B.1] >> > >> > >> > >> > Hynek >> > --------------------------------------------------------------------- To unsubscribe, e-mail: user-unsubscr...@commons.apache.org For additional commands, e-mail: user-h...@commons.apache.org
