LEGACY APPLICATION INTO HIGH SCALABLE ARCHITECTURE Morten Jokumsen - - PowerPoint PPT Presentation

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LEGACY APPLICATION INTO HIGH SCALABLE ARCHITECTURE Morten Jokumsen - - PowerPoint PPT Presentation

Dec 20, 2022 31 likes •416 views

TRANSFORMING A RUNNING LEGACY APPLICATION INTO HIGH SCALABLE ARCHITECTURE Morten Jokumsen eBay classifieds eBay Inc. confidential Morten Jokumsen Software Architech Email: mjokumsen@ebay.com Skype: guidmaster Twitter:

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eBay Inc. confidential

TRANSFORMING A RUNNING LEGACY APPLICATION INTO HIGH SCALABLE ARCHITECTURE

Morten Jokumsen eBay classifieds

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  • Morten Jokumsen
  • Software Architech
  • Email: mjokumsen@ebay.com
  • Skype: guidmaster
  • Twitter: guidmaster
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eBay Inc. confidential

Who and what is DBA?

  • Old classifieds news paper started in 1981
  • First website launched in 1995
  • Sold to eBay in 2008

– Price: 370 mill UDS

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eBay Inc. confidential

DBA 1996

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DBA 1997

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DBA 1999

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DBA 2000

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DBA 2002

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DBA 2004

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DBA 2005

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DBA 2007

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DBA 2008

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DBA 2010

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DBA 2012

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Who is DBA

  • One of the largest websites in DK
  • Grows 20% each year
  • Mobile traffic goes crazy!

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eBay Inc. confidential

THE CHALLENGE

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Get rid of this!

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Project Mercury

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Why Mercury?

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Within the realm of astrology the planet Mercury is the ruler of the star sign Gemini. Gemini means twins. This is what we want to do here seen from a business perspective: create a twin of dba.dk running on a more efficient, productive and high-quality platform.

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What we wanted

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Initial guidelines

  • The architecture must be simple and uniform
  • Use the Domain Driven Design patterns to gain uniform code and design of the

architecture

  • Code should be high quality which means low bug count and high maintainability
  • Performance need to be part of the architecture from the start
  • The architecture is scalable, which made it's easy to scale horizontal by append more

servers to make higher throughput

  • To ensure high quality and clean code, we migrate the existing database in steps to a

new database

  • We migrate with a business scope one to one

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The challenges

  • Move the architecture from 1999
  • Totally new team

– Understand the business

  • Move existing developers to .NET
  • Totally new technology stack

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And how we did it the first time

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Why did it suck?

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AND WE DID THE SAME MISTAKE IN THE NEXT PHASE

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The first write side

  • Fighting the O/RM
  • Anemic Domain Model

– Where did the logic go?

  • Did we do it wrong?

– Layered architecture failed?

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eBay Inc. confidential

LET´S SCALE

Evolve the code base

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The problems

  • We could not scale
  • We could not implement new stuff fast enough
  • New developers had a hard time to understand the code base
  • We said we we did DDD – but we didn´t

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CQRS TO THE RESCUE

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Our implementation of CQRS

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The advantage of CQRS

  • We can scale
  • We can implement new stuff fast!
  • We have a clean code base
  • New developers can easily follow the code base
  • We know where logic should go

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The advantage of ES

  • We can change the implementation of the domain
  • We can scale
  • Replay the stream
  • We can debug and fix live bugs
  • We have better business insight

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The new platform

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ASP.NET MVC MS SQL Server jQuery DDD FAST Nagios Memcached LINQ2SQL ADO.NET Entity Framework Dapper Miniprofiler CQRS Event Store RabbitMQ

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Where we ended

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Q&A

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