19 aug 2014 kl. 13:49 skrev Patrik Nordwall <[email protected]>:
> On Tue, Aug 19, 2014 at 1:46 PM, Martin Krasser <[email protected]> > wrote: > > On 19.08.14 13:40, Patrik Nordwall wrote: >> >> >> >> On Tue, Aug 19, 2014 at 1:35 PM, Martin Krasser <[email protected]> >> wrote: >> >> On 19.08.14 13:00, Roland Kuhn wrote: >>> >>> 19 aug 2014 kl. 11:28 skrev Ashley Aitken <[email protected]>: >>> >>>> >>>> >>>> On Tuesday, 19 August 2014 16:53:46 UTC+8, Martin Krasser wrote: >>>> >>>> journal -> akka actor(s) -> read model datastore >>>> >>>> when I can do this much more efficiently via >>>> >>>> journal -> spark -> read model datastore >>>> >>>> directly, for example >>>> >>>> I am confused, are you suggesting that spark is talking to the journal >>>> data store directly, without any involvement of Akka / Akka Persistence? >>>> If so, it sounds like a great solution but why would that require an >>>> extension to the Akka Persistence design/API? >>> >>> Well, another comment is that spark uses Akka actors in its implementation, >>> so I don’t see why it would magically be “much more efficient”. I think we >>> are mixing up two concerns here, will reply later when I can type properly >>> again. >> >> This is a misunderstanding. As mentioned in my previous message, scaling >> reads through a single journal actor doesn't work, it's not about that I see >> a general performance issue with Akka actors. >> >> >> >> I think the integration "akka persistence -> kafka -> spark -> whatever" >> looks great, but not everybody has that infrastructure, and therefore we >> provide PersistentView as a simple way to replicate events to the read side, >> and then a de-normalized representation can be stored in whatever makes >> sense for the queries. > > Of course, that should be possible too, and as I already said, backend store > providers can choose to use the very same backend for both plugins. There is > absolutely no need that applications must use Spark as part of their > infrastructure infrastructure. But if it is needed in large-scale > applications, a seconds plugin API for on the read side would make things > much more flexible. For users, who just want to have a single backend store, > they just have to configure one additional line (plugin) in their application > conf. > > >> >> Martin, what do you suggest? Removing PersistentView altogether? > > No, not at all, with an additional plugin, PersistentViews should have the > option to read transformed/joined/... streams from a backend store that is > optimized for that. > > ah, now I understand what you mean. That makes sense. I’m not completely there yet: in which way does this require changes to Akka Persistence? The only thing we need is to support multiple Journals in the same ActorSystem, and a way for PersistentView and PersistentActor to select between them, is this what you mean? Or do you mean that the read-side would be a new kind of plugin? OTOH this would not solve the read-side concerns raised by Greg: building a View on top of an incoming event stream is precisely not what he wants, unless I got that wrong. The idea behind CQRS/ES is that the events from the write-side drive updates of the read-side which is then queried (i.e. actively asked instead of passively updating) in whatever way is appropriate (e.g. graph searches). Regards, Roland > /Patrik > > >> >> /Patrik >>> >>> Regards, >>> >>> Roland >>> >>>> >>>> >>>> >>>> >>>> >>>> -- >>>> >>>>>>>>>> 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. >>> >>> >>> >>> Dr. Roland Kuhn >>> Akka Tech Lead >>> Typesafe – Reactive apps on the JVM. >>> twitter: @rolandkuhn >>> >>> >>> -- >>> >>>>>>>>>> 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. >> >> -- >> Martin Krasser >> >> blog: 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://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. >> >> >> >> -- >> Patrik Nordwall >> Typesafe - 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. > > -- > Martin Krasser > > blog: 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://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. > > > > -- > > Patrik Nordwall > Typesafe - 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. Dr. Roland Kuhn Akka Tech Lead Typesafe – Reactive apps on the JVM. twitter: @rolandkuhn -- >>>>>>>>>> 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.
