CQRS AT DBA Morten Jokumsen eBay classifieds Morten Jokumsen - - PowerPoint PPT Presentation

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CQRS AT DBA Morten Jokumsen eBay classifieds Morten Jokumsen - - PowerPoint PPT Presentation

Mar 25, 2024 315 likes •647 views

CQRS AT DBA Morten Jokumsen eBay classifieds Morten Jokumsen Software Architect @ eBay Classifieds Email: mjokumsen@ebay.com Skype: guidmaster Twitter: guidmaster The company Part of eBay Classifieds Bilbasen DBA

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CQRS AT DBA

Morten Jokumsen eBay classifieds

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  • Morten Jokumsen
  • Software Architect @ eBay Classifieds
  • Email: mjokumsen@ebay.com
  • Skype: guidmaster
  • Twitter: guidmaster
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The company

  • Part of eBay Classifieds
  • Bilbasen
  • DBA
  • Bilinfo
  • All leaders in their respective markets
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What is DBA

  • Started as a printed paper
  • By fare the largest classifieds site in DK
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How DBA looked like before

  • An old legacy platform
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On big monolithic platform

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Where we what to be?

  • Domain Driven Development
  • Build scalable solutions
  • Be able to innovate our business
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What is CQRS?

“CQRS is simply the creation of two objects where there was previously only one. The separation occurs based upon whether the methods are a command or a query (the same definition that is used by Meyer in Command and Query Separation: a command is any method that mutates state and a query is any method that returns a value).”

  • Greg Young
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… and when to use it

  • Scalability matters
  • Large team
  • Difficult business logic
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Why did we choose CQRS?

  • We need to scale our application
  • We need to integrate with other services
  • We have limited developer resources
  • We need to innovate
  • We wanted small manageable solutions
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How we started

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The results

  • Initial benefits
  • Scaling developer productivity
  • Scaling our read-side
  • ….. and the first problems
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But we saw the potential

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SYI

  • This is where we make revenue
  • This is where we can innovate
  • This is where our real business is
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The good

  • Introducing Event Sourcing
  • Introducing Sagas or Process Managers
  • Async events
  • Debugging live problems
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The bad

  • Introducing Event Sourcing
  • Async events
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Notes from a developer

  • The good
  • SRP
  • Addition instead of modification
  • The bad
  • Mental shift
  • Easy to fall back to just doing crud
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And the problems we faced

  • Upgrading events
  • Inconsistency between read-models and ES
  • Operations

– Date retention

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Key points

  • CQRS is not complicated
  • Smaller is better
  • Take the principals and apply elsewhere
  • Remember the mental changes
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Backup

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Integration with Events

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Method Chaining