You understand it right. Unfortunately, your solution won't work. Suppose player has 30/100 health (current/max) and 99/100 experience and two messages are sent to him with this order:
AddExperience(10) TakeDamage(40) Correct behaviour is that first 10 xp is added to 109/100 ... level is earned which cause to gain full hp 100/100. Only after then TakeDamage can by applied which causes to change player's hp to 60/100. If you would send LevelEarned to self, it will be processed after TakeDamage message and player will die. I would like to process each command at the time and persist ALL its consequence. Problem is that my consequences are found asynchronously :( Dne pondělí 19. října 2015 12:15:33 UTC+2 Patrik Nordwall napsal(a): > > If I understand it correctly your question is about how to persist the > LevelEarned event which comes via the > asyncrounous player.observable.subscribe callback. Since this is an actor > you must turn that callback into a message that is sent to self and when > receiving that message you can persist it. > > /Patrik > > On Mon, Oct 12, 2015 at 3:17 PM, Adam Dohnal <[email protected] > <javascript:>> wrote: > >> Hello, >> >> I am new in Akka and I am trying to develop some mini project to test >> some things (akka, rx, cqrs, es etc..) >> >> I think I understand the concept of cqrs/es and how it fit to akka. My >> problem is probably more theoretical than technical. >> >> Let's say, I have class Player, which has several Attribute[T] attributes >> ... these attributes can be for example player's current health, vitality, >> experience, level etc ... These attributes have dependencies ... for >> example currentHealth is defined as 10 * vitality ... if experience is > >> 100 new level is earns, which causes to add 1 vitality, which causes to add >> 10 health ... Hopefully, you get the point. >> >> I like the idea to implement this using reactive streams. Each >> Attribute[T] should be considered as Observable[T] and with all these >> excellent operators I can model dependencies I have described before. >> >> Now I am trying to model each Player as actor, which can handle commands >> (AddExperience(...), AddVitality(...) etc...) and produce events >> (ExperienceAdded(...), LevelEarned(...)) which should be event sourced. >> >> Problem is, that when I am handling command I directly don't know what >> events should be generated ... for example AddExperience(100) is handled >> and after some validation ExperienceAdded(100) should be persisted to event >> store. When it success, it should be applied to my domain, which emit value >> change in that attribute observable and new level can be earned ... but how >> can I persist that event? >> >> I try to write some pseudo-code >> >> class ExamplePersistentActor extends PersistentActor { >> val Player player = ... // domain >> >> val subscription = player.observable.subscribe { >> // here I get asynchronously information about that level is increased >> ... should I call persist here? >> } >> >> val receiveCommand: Receive = { >> case AddExperience(xp: Int) => { >> persist(ExperienceAdded(xp)) { event => >> player.addExperience(xp) // should produce LevelEarned(1) event, which >> should be also persisted >> } >> } >> } >> >> So I have reference to Player which has observable of all events that are >> produced ... but I don't how to persist them :/ >> >> -- >> >>>>>>>>>> Read the docs: http://akka.io/docs/ >> >>>>>>>>>> Check the FAQ: >> http://doc.akka.io/docs/akka/current/additional/faq.html >> >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user >> --- >> You received this message because you are subscribed to the Google Groups >> "Akka User List" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected] <javascript:>. >> To post to this group, send email to [email protected] >> <javascript:>. >> Visit this group at http://groups.google.com/group/akka-user. >> For more options, visit https://groups.google.com/d/optout. >> > > > > -- > > Patrik Nordwall > Typesafe <http://typesafe.com/> - Reactive apps on the JVM > Twitter: @patriknw > > -- >>>>>>>>>> Read the docs: http://akka.io/docs/ >>>>>>>>>> Check the FAQ: >>>>>>>>>> http://doc.akka.io/docs/akka/current/additional/faq.html >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user --- You received this message because you are subscribed to the Google Groups "Akka User List" group. To unsubscribe from this group and stop receiving emails from it, 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/d/optout.
