Hi Prakhyat, the misunderstanding stems from the fact that there are two layers of querying involved. User code asks the read-side for current information, which is the query you mean, but that is not what we are talking about in Akka Persistence. Akka does not really care how you structure your data for user queries since there are a multitude of possible use-cases and solutions to that. What we do care about is only how Actor Persistence works and how that meshes with a CQRS system in general.
Therefore the Query mentioned in “The Conclusion” is only about how the read-side extracts the data from the Journal, nothing more. The read-side will consume the stream of updates (events) and use them to maintain the current state which is then queried by the user. The term Query is a very generic one, but unfortunately it also is the correct one for both kinds of uses. Regards, Roland 8 sep 2014 kl. 09:26 skrev Prakhyat Mallikarjun <[email protected]>: > Team, > > I am unable to decode Akka Persistence on the Query Side: The > Conclusion(https://groups.google.com/forum/#!topic/akka-user/MNDc9cVG1To) > entirely. > > Correct me if I am wrong, the discussion hints at making use of akka streams > for querying in CQRS systems. > > I want to understand how history of events can be useful for querying. > Querying I mean, business specific querying or complex reporting spanning > multiple aggreagate roots. > > As I understand any querying will require current state. I am unable to > fathom, how streams of events can be used for responding to queries. > > Will queries, fetch the events from streams, replay them in run time and > prepare state? > > Please provide a use case or practical example to make us understand. If your > example can include multiple aggregate roots, it will be even better. > > -Prakhyat M M > > -- > >>>>>>>>>> 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.
