michaltomanski / cqrs-demo Goto Github PK

I've been playing around with this cqrs-demo project, and have forked it to experiment a bit. In my fork, I've created a LoggerBestAvgViewBuilder that just takes the tagged events from the persistence query stream and logs them to the console (I don't care about the read side DB implementation at this point). It works well, and as I start/stop the timer in the browser, I can see the BestAvgChanged event being logged to the console as expected.

The issue is that I can't get either the PersistentActor recovery or the readJournal.eventsByTag to work reliably when I try to make a prototype of my own. In fact, as I'm building out prototypes, (spikes or our actual project at work), I'm noticing that recovery is "senstive" - sometimes it works, and sometimes it doesn't. When it doesn't work, there are no errors in the log, just the Actor logging 'RecoveryCompleted` with a "zero" state, no events get played back, even though I can see the events in the Cassandra table. I think what I'm experiencing as "sensitivity" is me being ignorant of either some configuration issue, or I'm mis-managing my Cassandra instance somehow.

Similary, I can get a singleton actor up and running with an Akka Stream for the projector/persistence-query piece, no errors log, but the tagged data won't flow (my WriteEventAdapter is working and I can see the tags in the Cassandra table). My hunch is that if PersistentActor recovery isn't working, then the CassandraReadJournal projector won't work either. It seems to consistently be a "play-back" problem, whether for PersistentActor recovery, or for a CassandraReadJournal projector.

Are there any pitfalls that you are aware of that newbies like me commonly fall into when setting up an Akka solution with akka-persistence-cassandra? I guess with this being a leading edge technology, there aren't any tutorials (other than a couple of demo projects like this) that get through the nuts and bolts like that.