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11º PHPSC InCompany

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Guilherme Augusto Henschel a.k.a. Cenoura developer since 2009 working @ Nexaas

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Notice ✘ this talk intent is to open your mind ✘ use these patterns carefully ✘ remember, there is no silver bullet

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ORM Customer Memory Database Customer Account owns name address account Account accountNumber type balance

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Event Sourcing

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“ Event Sourcing ensures that all changes to application state are stored as a sequence of events. — Martin Fowler

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AccountCreated id: 123 owner: Guilherme H. 1 DepositPerformed accountId: 123 amount: $50 2 WithdrawalPerformed accountId: 123 amount: $20 3

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Pros ✘ complete log of every state change ✘ easy way to undo things ✘ testing, traceability and debugability ✘ business and data analysis of event streams ✘ immutability

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Cons ✘ complexity ✘ time to get used to ✘ limited support from frameworks

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When ✘ rich object-oriented domain models ✘ critical accountability and debugability ✘ version control for data ✘ data can give you competitive advantage ✘ building scaleable systems based on CQRS pattern

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CQS Command Query Segregation

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“ every method should either be a command that performs an action, or a query that returns data to the caller, but not both. — Bertrand Meyer

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CQRS Command Query Responsibility Segregation

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“ creating two objects where there was previously only one

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Before

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Improving

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After

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Pros ✘ scalability ✘ flexibility ✘ reduced complexity ✘ concentrate on domain/business

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Cons ✘ complexity

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When ✘ task based user interfaces ✘ complex data processing ✘ disparity in reads and writes

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Event Sourcing + CQRS

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Libs/Components ✘Broadway - https://github.com/broadway/ broadway ✘Prooph - http://getprooph.org/

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thanks! guilhermeaugusto.com.br

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References ✘ Greg Young talk - https://www.youtube.com/watch?v=JHGkaShoyNs and https://cqrs.files.wordpress.com/2010/11/cqrs_documents.pdf ✘ Johannes Seitz talk - https://ookami86.github.io/event-sourcing-in- practice/ ✘ Martin Fowler articles - https://martinfowler.com/eaaDev/ EventSourcing.html and https://martinfowler.com/bliki/CQRS.html ✘ Marco Pivetta talk - https://www.youtube.com/watch?v=8NuHNtwjync ✘ http://www.cqrs.nu/ ✘ https://speakerdeck.com/owolf/cqrs-for-great-good ✘ https://speakerdeck.com/mattketmo/cqrs-and-event-sourcing