On Sun, Feb 27, 2011 at 11:51 AM, Jacob Beard <jbea...@cs.mcgill.ca> wrote: > Hi, > > I'm currently working on revising scxml-js so that it implements the > semantics defined by the step algorithm of the SCXML specification (as > opposed to the mixture of SCXML semantics and Rhapsody semantics which > it currently implements). I've run into a part of the step algorithm > which is somewhat unclear, and because it may relate to a limitation > in the Commons SCXML implementation, I thought I would ask about this > on the Commons SCXML list before asking about it on the w3-voice list. > > Consider the following SCXML document: > > <scxml initial="p"> > > <parallel id="p"> > > <history id="h"> > <transition target="A.2 B.2"/> > </history> > > <state id="A" initial="A.1"> > <state id="A.1"/> > <state id="A.2"/> > </state> > > <state id="B"> > <state id="B.1"/> > <state id="B.2"/> > </state> > > </parallel> > > </scxml> > > (https://gist.github.com/846316) > > > I believe the step algorithm in the SCXML specification would > interpret the document in the following way: > > addStatesToEnter would at some point be called for parallel state p. > addStatesToEnter would then be called recursively for each of p's > children: h, A, B. > > addStatesToEnter would first be called for h. Because this is the > first time h was entered, addStatesToEnter will be recursively called > for each of the targets of its default transition: A.2 and B.2. A.2 > and B.2 will then be added to statesToEnter. > > addStatesToEnter would then be called for state A. A is a compound > state, so addStatesToEnter would then be called for A's initial state: > A.1. A.1 would then be added to statesToEnter. > > The same would occur for B, and so B.1 would be added to statesToEnter. > > The resulting configuration would then be: p,h,A,B,A.1,A.2,B.1,B.2, > which is not a legal configuration, as A and B are both OR states. > > > > Is my interpretation of the specification correct, in that the step > algorithm would allow this illegal configuration, or am I missing > something? > > > > I'm asking this question here, rather than on the w3-voice list, > because I believe Commons SCXML does not currently support history in > parallel: > http://mail-archives.apache.org/mod_mbox/commons-user/201001.mbox/%3cce1f2ea81001131340w2aaaf5bfs84b9db2252287...@mail.gmail.com%3E > > It's not clear whether this is due to possible conflicts in SCXML > semantics, or whether this is simply Commons SCXML implementation > lagging a bit behind changes in the specification. > <snip/>
Its lag. I believe you have your answer on w3-voice, if not, let me know and I'll look further. -Rahul > I'd appreciate any guidance you can offer. Thanks, > > Jake > --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org For additional commands, e-mail: dev-h...@commons.apache.org
