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CQRS for everyone

Maciej Aniserowicz

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Agenda• CQRS = Command Query Responsibility Segregation

• read-side• demo

• write-side• demo

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Anti-agenda(because: „for everyone")

• Event Sourcing

• Message Queues

• Multiple data stores

• NoSQL

• DDD

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Command QueryResponsibility Segregation

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READ – problems• queries on „domain” model

• complicated SQL generated by ORM

• repository pattern

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READ - demo

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WRITE – problems• „fat” controllers

• system API all over the place

• maaaany dependencies

• hard to test

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WRITE - demo

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Examples (Dialer app)• Callbacks – in Dialer application

• schedulle a "callback" in X minutes when person phone is busy

• WhenPhoneBusy_ScheduleCallback

• CallbackSelector : ISelectNextPersonToDialStrategy

• another event: "callback scheduled"

• "Agent ranking"• who sold the most? - handle OrderTaken event

• who talked to most customers? - handle PhoneAnswered event

• ...

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When NOT to apply?

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Recap• read

• as simple as possible

• write• focus on what is really IMPORTANT

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THX! and...http://bit.ly/ma-181116

discount: netdd (-35%)

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Questions...?

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