Hi Roland,

great conclusion, with everything said till now in mind. I'd like to 
mention a view points and like to hear if this matches your thoughts:

The  QueryByTypeDeterministic(type, from, to) mentioned by Martin matches 
with the way I've been using DDD+CQRS for last 2 years. 
Meaning that the type is actually the type of the PersistentActor. (not of 
an event) 
By streaming all events of a certain PersistentActor type, it's possible to 
create current state (for instance in a RDBMS or Graph database) that is 
used by the application. The application Queries these stores (RDBMS/Graph) 
and will not use the event stream or journal in a direct way. (so the real 
performance requirements are somewhere else)

I believe that it is quite important to have these API case classes 
standardized as much as is reasonably possible. Because that allows me to 
use another persistent store for testing (like leveldb / inmem) while in 
production it makes use of kafka or some other store. 
I'd prefer to have the akka-persistence layer in between, allowing me to 
choose the setup according to the situation. (instead of tying directly to 
a kafka topic / eventstore stream)

One remark about the QuerySuperscalableTopic (or kafkatopic) 
I assume the 'name' parameter has to be created in the store in question 
(just like an index for an RDBMS). 
This feels like moving part of the responsibility of the way your CQRS 
framework works towards an external component (if this 'index' is not 
created, the thing does not work). When you look at the initial 'tag' 
proposal, you had to code a tag (write side) that could be used on the read 
side.
In this construction you will be able to test the code setup without being 
dependent on a specific store setup. 


Kind regards, 

Olger


>

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