Isn't this section of the docs naïve in the face of possible errors? http://doc.akka.io/docs/akka/current/scala/persistence-query.html#Materialize_view_to_Reactive_Streams_compatible_datastore
Later on that page is an incomplete example of a resumable projection. Won't something like that need to be the norm? On Fri, Feb 26, 2016 at 1:55 PM, Richard Rodseth <[email protected]> wrote: > Hmm. I see the fromSequenceNr parameter in the query traits. So the read > side would have to persist a watermark? Where? I was hoping for less > boilerplate. > > On Fri, Feb 26, 2016 at 5:47 AM, Patrik Nordwall < > [email protected]> wrote: > >> >> >> On Wed, Feb 24, 2016 at 10:33 PM, Richard Rodseth <[email protected]> >> wrote: >> >>> In Vaughn Vernon's Red Book (Implementing DDD) he talks about storing >>> domain events in the same transaction as the one which updates an >>> aggregate, and then out of band you read this domain event store (not in >>> the event sourcing sense) in order to put messages on a message queue, for >>> example, to notify remote bounded contexts. >>> >>> In an akka-cassandra-kafka world, with no transactions, I imagine an >>> actor with an akka persistence query stream, that is responsible for >>> putting a domain event on a Kafka topic. In this scenario, would errors >>> writing to the Kafka topic be handled with retries and ultimately human >>> intervention? Is the way to add retry semantics to stream computation to >>> send the stream contents to an actor ref which does the writing? >>> >> >> Easiest would probably be to use akka-persistence-kafka >> <https://github.com/krasserm/akka-persistence-kafka> as the persistent >> actor journal, but I think you are asking for something else. Assume that >> you store the events from the persistent actor to Cassandra, and then have >> a query to read that stream and put them into Kafka. If the Kafka write >> fails you have read the events from Cassandra again from the last know >> successful offset, and try again. >> >> /Patrik >> >> >>> >>> In short: are there any good examples yet of the akka persistence >>> approach to DDD, including published domain events (which I think are >>> distinct from raw persistence events). >>> >>> -- >>> >>>>>>>>>> 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 https://groups.google.com/group/akka-user. >>> For more options, visit https://groups.google.com/d/optout. >>> >> >> >> >> -- >> >> Patrik Nordwall >> Lightbend <http://www.lightbend.com/> - Reactive apps on the JVM >> Twitter: @patriknw >> >> [image: Lightbend] <http://www.lightbend.com/> >> >> -- >> >>>>>>>>>> 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 https://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. 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 https://groups.google.com/group/akka-user. For more options, visit https://groups.google.com/d/optout.
