On 20.02.14 16:38, [email protected] wrote:
On Thursday, February 20, 2014 9:23:48 PM UTC+8, Martin Krasser wrote: On 20.02.14 14:00, Patrik Nordwall wrote:On Thu, Feb 20, 2014 at 1:47 PM, <[email protected] <javascript:>> wrote: To create an order, we need to check balance first and if fund is insufficient, no event will be generated; To cancel an order, we need to check the order exists and is still pending. Anyway, my point is, there might be scenarios like this where two EventsourcedProcessor might be necessary to co-exist and work together though one or two channels in between. The current limitation prevents an EventsourcedProcessor form sitting behind a PersistentChannel... I think you have a good point. I don't know how difficult it would be to support it,that's a minor addition to let ConfirmablePersistent messages through. OTOH, letting to (eventsourced) processors communicate with each other via channels smells like someone wants to extend a consistency boundary beyond a single actor, especially if state of actor A needs to be checked to conditionally update state of actor B and vice versa (as in the given example). In this case, both processors should be collapsed into a single one.Martin, using one single eventsourced processor greatly simplifies the example, but we have scalability and performance concerns.
This doesn't mean having the whole application state in a single processor. Instead of partitioning accounts and orders, you could also partition by user, for example, keeping accounts and orders for a subset of users within a processor. See also the cluster sharding <http://doc.akka.io/docs/akka/2.3.0-RC4/contrib/cluster-sharding.html> feature of Akka. This is just a thought - I don't know the requirement details of your applications. Just wanted to mention there are multiple to achieve write scalability.
but feel free to create a ticket and we will investigate it. The least we can do is to document the limitation (well, it's already documented in the ScalaDoc) and how to work around it. /Patrik On Thursday, February 20, 2014 6:17:46 PM UTC+8, Martin Krasser wrote: Why don't you let M2 handle createOrder and cancelOrder commands and emit orderCreated and orderCanceled events to M1? This way you could use EventsourcedProcessor to implement M2 and a Processor to implement M1. On the other hand, it's a bit difficult to give an advise here without knowing validation, consistency and other requirements On 20.02.14 08:40, dong wrote: > Martin, let me figure out a empale to make my point. > > Suppose my app is a trading platform, it has two memory based models - > account balances (M1), and pending orders (M2). The > deposit/withdraw/createOrder commands shall be handled by M1, lets say > after processing a 'crateOrder' event, it reduced the account balance, > and then sent a 'OrderCreated' event to M2 for updating pending order > set. On the order hand, cancelOrder commands are handled by M2 > directly and after an order is cancelled, M2 needs to send an event to > M1 to increase the balance (in case an order doesn't exist, no event > is ever persisted). > > In such a use case, both M1 and M2 shall be Eventsourced processors, > and I'd like them to work together. Does this make any sense?-- Martin Krasserblog: http://krasserm.blogspot.com code: http://github.com/krasserm twitter: http://twitter.com/mrt1nz-- >>>>>>>>>> Read the docs: http://akka.io/docs/>>>>>>>>>> Check the FAQ: http://akka.io/faq/ >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user <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 <http://groups.google.com/group/akka-user>. For more options, visit https://groups.google.com/groups/opt_out <https://groups.google.com/groups/opt_out>.--Patrik Nordwall Typesafe <http://typesafe.com/> - Reactive apps on the JVM Twitter: @patriknw-- >>>>>>>>>> Read the docs: http://akka.io/docs/>>>>>>>>>> Check the FAQ: http://akka.io/faq/ >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user <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 <http://groups.google.com/group/akka-user>. For more options, visit https://groups.google.com/groups/opt_out <https://groups.google.com/groups/opt_out>.-- Martin Krasserblog:http://krasserm.blogspot.com code:http://github.com/krasserm twitter:http://twitter.com/mrt1nz
-- Martin Krasser blog: http://krasserm.blogspot.com code: http://github.com/krasserm twitter: http://twitter.com/mrt1nz --
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