Ah, this looks very nice and I agree that it sounds easier to implement, and would perfectly cover my use case. Hopefully it will be implemented soon :)
Thanks! -Mario. On 07 Jul 2014, at 14:05, Martynas Mickevičius <martynas.mickevic...@typesafe.com> wrote: > Hi Mario, > > your use case resonates to me with the "Hot Standby Processor" feature > request, that we have in our issue tracker. In that case you would have only > one Processor which does the writes. But next to that there would be a number > of Hot Views that do reads and can be promoted to the Processor if the > original dies. > > I know this is a bit different from the idea you are proposing, but this may > be easier to implement than synchronizing stores of multiple processors. > > > On Fri, Jul 4, 2014 at 7:01 PM, Mario Camou <mca...@tecnoguru.com> wrote: > Hi everyone, > > I'm in the process of thinking through a rewrite of parts of an application > using Akka Persistence. After watching Endre's talk from ScalaDays (I was > unable to attend the talk itself and the streaming only made me sadder about > that) I was thinking, is there a plan to apply this sort of thinking to > PersistentActors? > > I was thinking of a cluster where you have several instances of a > PersistentActor, behind a Cluster-Aware Router (not using a Cluster Singleton > because of scalability). The thing is (as far as I've been able to > determine), each PersistentActor has its own state (and event store), so they > don't have any sort of shared (eventually-consistent) view of the world. > Since Akka Cluster already uses the Gossip protocol to maintain cluster > state, perhaps it would be interesting to extend that so that Events get > propagated too. > > For a little more perspective, here's what I am thinking of doing. Currently > the application (running in a single server) holds state in in-memory Maps > coordinated using STM. The elements in these maps are persisted to JSON files > every time there's an update so that, when the system goes down and back up, > it can restore them. I was thinking of changing this to use Akka Persistence. > > Currently a single process handles both the backend (in this case, > communicating with e-bike rental stations) and frontend responsibilities > (exposing the state via REST calls using Spray and allowing the web front-end > to modify the state). They both access the store via a Repository object > which takes care of querying and updating the Maps. I was thinking that, by > using Akka to access the Repository (instead of method calls) I could then > scale the system out by separating the frontend and backend into separate > nodes. That, however, still leaves me with a Single Point of Failure: the > Repository itself. If I could have the PersistentActors communicate amongst > themselves to keep an eventually-consistent view of the world, it would allow > me to replicate the Repository to several nodes, or perhaps not even having a > dedicated process to hold the PersistentActors, instead hosting them in the > same cluster nodes as the backend(s) and frontend(s). > > As I asked earlier, is this planned at some point, is there some other > recommended way of going about this, or am I completely out of the ballpark? > > Thanks, > -Mario. > > -- > >>>>>>>>>> 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 akka-user+unsubscr...@googlegroups.com. > To post to this group, send email to akka-user@googlegroups.com. > Visit this group at http://groups.google.com/group/akka-user. > For more options, visit https://groups.google.com/d/optout. > > > > -- > Martynas Mickevičius > Typesafe – Reactive Apps on the JVM > > -- > >>>>>>>>>> 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 akka-user+unsubscr...@googlegroups.com. > To post to this group, send email to akka-user@googlegroups.com. > Visit this group at http://groups.google.com/group/akka-user. > For more options, visit https://groups.google.com/d/optout. -- >>>>>>>>>> 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. 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