This document provides an overview of CQRS (Command Query Responsibility Segregation), describing it as a way to design disconnected solutions for distributed systems and complex applications handling high loads. It discusses the current "warrior's way" approaches and outlines some of the key principles of CQRS, including separating commands from queries, using event sourcing and messaging. The document also briefly mentions some example implementations and applications of CQRS in production systems.

1. The Art of CQRS Slava Pocheptsov Tech Leader pocheptsov pocheptsov@gmail.com

2. 1 Why? Distributed System Complex Enterprise Applications High Load Parallel Development

3. 2a Current Warrior's Way Layered Onion Structure

4. 2b Current Warrior's Way SOA

5. 2c Current Warrior's Way Custom Solution

6. 3a Overview CQRS – The Cult of Shiny Things Command Query Responsibility Segregation

7. Overview CQRS as a concept is a way of designing disconnected solutions 3b

8. 4 Reinvent the Wheel C Q R S

9. 5a Meaning

10. Meaning CQRS Principle CQRS Architecture DDDD How, What, Why? 5b

11. 6 Principle

12. 7 Architectures

13. 8 DDDD DDD - Aggregate Root Event Sourcing CQRS Messaging System

14. Queries View Model instead of DTO Query Data Storage Scaling 9

15. 10 Commands Perform Validation Rethinking UI Queue Scaling Independent Fallacy reuse

16. 11 Command Handler Combinations

17. Domain Model Aggregate Root within Command Handler Context Active Record SPs Monkey input 12

18. 13 Events Happened

19. 14 Storage Barrels

20. 15 Architecture Reminder

21. But…

22. Caveats Complexity? Out of order Distributed Transaction Data staleness Sagas Domain Design Focus on Domain Validation Task-Based UI Knowledge 16

23. 17 Value Saga oriented! first-one-wins, or last-one-wins Team collaboration Scaling Simplify complex logic support Part of SOA BASE

24. No numbers or charts

25. Implementation nCQRS Axon Framework Fohjin Lokad.CQRS BankSimplistic SimpleCQRS Agr.CQRS JDon 18

26. Demo

27. 19 Production LokadSalescast Amazon (SOA) No public available info about Enterprise systems Tvene

28. 20 Future

30. Answers http://blog.pocheptsov.com/p/cqrs-references.html http://cqrsinfo.com/http://codebetter.com/gregyoung/http://abdullin.com/http://groups.google.com/group/dddcqrshttp://blog.jonathanoliver.com/http://igor.quatrocode.com/http://cre8ivethought.com/http://www.dennisdoomen.net/http://thinkddd.com/http://www.udidahan.com/

31. @pocheptsov 31337