No - no orthogonal states. If I had that I'd look for a data-driven approach rather than coding each fsm as I have done good luck! Tim
On 4 January 2014 19:42, Nicholas Ustinov <[email protected]> wrote: > Thank you for response and for sharing experience. > Does your approach work good for orthogonal states of FSM (aka tag > "parallel" in SCXML), when FSM can have several active states at one time? > > > суббота, 4 января 2014 г., 22:20:48 UTC+4 пользователь Tim Pigden написал: > >> I tried to do hierarchical fsm using just nested akka fsms. It doesn't >> work (they never said it did) because of the problem of passing messages >> through to children asynchronously - you may have 2 messages come through >> in rapid succession and you have to manually queue the second one while >> you're firing up the new state. >> Then I considered "why should akka fsm support hierarchies via multiple >> actors". Surely the essence of the fsm is that it is only doing one thing >> at a time because it's only in one state at a time. You can't transition to >> a new state until you've finished with the old one. Actors are inherently >> doing different things at the same time - so other than the fact that we >> have a single tier fsm in Akka why start there as a means of abstraction of >> the problem? >> My solution was to create my own hierarchical fsm using immutable >> structures - essentially a stack (child changes, the stack changes, >> percolating upwards). Once I'd made the effort I found it suited me very >> nicely. All I need is to wrap it all in a single actor that processes >> incoming messages and passes them down. >> >> I think my conclusion is that just because akka does a single tier fsm >> nicely it doesn't mean that having multiple actors is a good model for a >> complex fsm. And if it's not done with multiple actors why do it with the >> akka fsm at all? With a bit of effort you could produce a dsl that was >> pretty similar to Akka's in terms of those nice gotos and transitions but >> in a single thread. The fsm is then only doing one thing at a time and the >> wrapper actor is handling the queuing for you. I didn't go as far as a dsl >> because I don't need to -my total model has 10 sub-fsms (including >> sub-sub-fsms) and probably no more than 30 different states so it wasn't >> worth too much api writing. >> >> Tim >> >> >> >> On Saturday, January 4, 2014 12:27:35 AM UTC, Nicholas Ustinov wrote: >>> >>> Hello! >>> >>> I found some useful discussions in this list about hierarchical FSMs, I >>> mean >>> https://groups.google.com/forum/?fromgroups#!searchin/ >>> akka-user/state$20machine/akka-user/Lqezg-y215g/TdiyWEklW7gJ >>> https://groups.google.com/forum/?fromgroups#!searchin/ >>> akka-user/state$20machine/akka-user/Sfl3Xcul86I/8HW1CZJoHtcJ >>> https://groups.google.com/forum/?fromgroups#!searchin/ >>> akka-user/first-day/akka-user/eX_3rZ-cNNw/kV9YNzsSnkUJ >>> >>> and some others. >>> >>> So I understand that akka's FSM realization doesn't have support of >>> hierarchical and parallel FSMs. But it's very interesting, if you have some >>> plans or thoughts for this? >>> Especially for orthogonal states of FSMs. >>> I think, for toy things or very simple abstractions current realization >>> will be good enough, but for real-world domain modeling you will need >>> support of smth like things, described in SCXML specification, i mean, >>> support for full-blown Harel state machines. >>> I ask because I need to implement some domain abstractions in this way >>> and i'm looking for the cheapest way for implementing it. >>> >>> Thank you, >>> Nicholas >>> >> -- > >>>>>>>>>> Read the docs: http://akka.io/docs/ > >>>>>>>>>> Check the FAQ: http://akka.io/faq/ > >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user > --- > You received this message because you are subscribed to a topic in the > Google Groups "Akka User List" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/akka-user/X-Awg4jlJk0/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/akka-user. > For more options, visit https://groups.google.com/groups/opt_out. > -- Tim Pigden Optrak Distribution Software Limited +44 (0)1992 517100 http://www.linkedin.com/in/timpigden http://optrak.com Optrak Distribution Software Ltd is a limited company registered in England and Wales. 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