CQRS


  1. https://cqrs.wordpress.com/documents/cqrs-introduction/
  2. http://udidahan.com/2009/12/09/clarified-cqrs/

CQRS vs. CQS

  1. https://martinfowler.com/bliki/CommandQuerySeparation.html
  2. https://martinfowler.com/bliki/CQRS.html
  3. https://stackoverflow.com/questions/34255490/difference-between-cqrs-vs-cqs

https://en.wikipedia.org/wiki/Command%E2%80%93query_separation

Command query responsibility segregation (CQRS) applies the CQS principle by using separate Query and Command objects to retrieve and modify data, respectively.

=> CQRS is not just about mechanical splitting read and write functions - it’s a comprehensive approach to processing requests which can include many aspects (say, read and write operations might even use different stores).

CQRS vs. ES

https://stackoverflow.com/questions/9199670/cqrs-without-event-sourcing-what-are-the-drawbacks

Event Sourcing is optional and in most cases complicates things more than it helps if introduced too early.

https://lostechies.com/jimmybogard/2012/08/22/busting-some-cqrs-myths

event sourcing is a completely orthogonal concept to CQRS

in CQRS you don’t have to use ES but this combination is quite popular so more often than not when people speak about CQRS they mean using ES as well.