1. CQRS, Related Patterns & Lessons Being Learned

2. What’s ahead Real quick overview of CQRS Some related patterns Event sourcing Pub-sub Experience Report from 2 CQRS projects (WIP) 1 Enterprise IT app in Insurance 1 cloud based app in Education

5. Separate methods for Commands & Queries From: Object-Oriented Software Construction, 2nd Edition by Bertrand Meyer

6. Technical Complexity From: http://blog.fohjin.com/blog/2009/11/12/CQRS_a_la_Greg_Young Complexity Problem/Domain

7. Façadelient Bus Commands Eventually Consistent Queries Handler

8. Subscriber Subscriber Publisher Subscribers Subscriber

9. ID : 123 Name : The Art of War Author: Sun Tzu ISBN: 1234ABCD5678 Event: BookIsbnChanged NewValue: 4321DCBA8765

10. …there are times when we don't just want to see where we are, we also want to know how we got there http://martinfowler.com/eaaDev/EventSourcing.html

11. publicclassBook : AggregateRoot<Book> { privatestring _name; privateIsbn _isbn; privateGuid _id; privateBook() { Handle<IsbnChangedEvent>(HandleIsbnChangedEvent); } … publicvoidChangeIsbn(ChangeIsbnCommandchangeIsbnCommand) { // Check any relevant business rules here IsbnChangedEvent @event = newIsbnChangedEvent(_id, changeIsbnCommand.Isbn); Apply(changeIsbnCommand); } publicvoidHandleIsbnChangedEvent(IsbnChangedEvent @event) { _isbn = @event.NewIsbn; } }

12. Experience Report 1: Application to be used to let Brokers create quotes and policies High Volume, low margin Integration with legacy app for reporting Legacy (& painful) Database

13. Document Generator Gateway DMS Policy Store Rating Data Reference Data Legacy Rating Engine Reports Reference Data Documents Domain & Plugins Handlers Façade – API (MVC) Client Web App

14. Experience Report 2: Users are regional reps of an exam board Globally located Integrate with back office systems Business benefit Allow business to grow with growing costs Provide a better service to customers

15. Main Event Store Reports Reports Handler API Handler Query API Domain API Domain Smart Client Web Client

16. Now go see: Videos CQRS E-VANs - Greg Young, UdiDahan, Mark Nijhof Event Sourcing - InfoQ Ian Cartwright Blogs Greg Young (CodeBetter) UdiDahan Mark Nijhof (Elegant Code) Code Samples/Frameworks (all Event Sourced) http://github.com/MarkNijhof/Fohjin (.NET) http://github.com/erikrozendaal/cqrs-lottery (Java) http://code.google.com/p/axonframework/ (Java)