...hai detto CQRS a chi ?!?!?!
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Se dicessi "CQRS+ES"? ...se state già cercando su wikipedia questo talk è per voi. Introduzione a CQRS ed Event Sourcing per persone che odiano gli acronimi. 100% fluff free. Intervento tenuto al meeting #programmersinpadua il 15 settembre 2015
...hai detto CQRS a chi ?!?!?!
- 1. …WHAT’S THAT CQRS THING? introduction for adopters effect free!
- 6. is an architectural pattern proposed by Greg Young that segregates reads and writes of a system into two separate subsystems. CQRS
- 7. writes are usually asynchronous and stored in a transactional storage while reads are eventually consistent and retrieved from de-normalised views CQRS (details)
- 8. BERTRAND MAYER Designer of Eiffel programming language Coined “open/closed principle” and “design by contract” Introduced command query separation (CQS)
- 9. Use of commands and queries separates write and read concerns
- 10. COMMAND Tell to do something
- 11. COMMAND ? Command is the message to change state ? Message handled by a CommandHandler ? Returns void (so nothing) ? Describes business intent ? Immutable
- 12. QUERY Fetch state from data store
- 13. QUERY ? Read state from data store ? Does not change state ? Has a return value
- 14. WHY SHOULD I USE CQRS? ? Scalability ? Reduced complexity ? Flexibility ? Focus on the business
- 15. ? Fear of change ? Mental leap ? All-Or-Nothing approach BE AWARE OF
- 16. CQRS MYTHS ? is easy ? CQRS = Event Sourcing and vice versa ? requires an eventual consistent read store ? requires a bus/queues/asynchronous messaging
- 17. – Udi Dahan “Most people using CQRS (and event sourcing too) shouldn't have done so” – GregYoung “It's important to note though, that these are things you can do, not necessarily things you should do. Separating the read and write models can be quite costly” WHEN SHOULD I AVOID IT?
- 18. WHATS NEXT? ? Event sourcing (ES) ? Eventual consistency ? Task based UI ? …
- 21. CREDITS slide10 - www.defenceimagery.mod.uk - 45155579 slide 12 - https://www.?ickr.com/photos/broeckxsven/ slides 4,9 - http://martinfowler.com/bliki/ http://martinfowler.com/bliki/CQRS.html http://udidahan.com/2009/12/09/clari?ed-cqrs/ https://en.wikipedia.org/wiki/Command–query_separation https://cqrs.?les.wordpress.com/2010/11/cqrs_documents.pdf RESOURCES