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

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: guidmaster

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 3 eBay Inc. confidential

DBA 1996 4 eBay Inc. confidential

DBA 1997 5 eBay Inc. confidential

DBA 1999 6 eBay Inc. confidential

DBA 2000 7 eBay Inc. confidential

DBA 2002 8 eBay Inc. confidential

DBA 2004 9 eBay Inc. confidential

DBA 2005 10 eBay Inc. confidential

DBA 2007 11 eBay Inc. confidential

DBA 2008 12 eBay Inc. confidential

DBA 2010 13 eBay Inc. confidential

DBA 2012 14 eBay Inc. confidential

Who is DBA • One of the largest websites in DK • Grows 20% each year • Mobile traffic goes crazy! 15 eBay Inc. confidential

THE CHALLENGE 16 eBay Inc. confidential

Get rid of this! 17 eBay Inc. confidential

Project Mercury 18 eBay Inc. confidential

Why Mercury? 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. 19 eBay Inc. confidential

What we wanted 20 eBay Inc. confidential

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 21 eBay Inc. confidential

The challenges • Move the architecture from 1999 • Totally new team – Understand the business • Move existing developers to .NET • Totally new technology stack 22 eBay Inc. confidential

And how we did it the first time 23 eBay Inc. confidential

Why did it suck? 24 eBay Inc. confidential

AND WE DID THE SAME MISTAKE IN THE NEXT PHASE 25 eBay Inc. confidential

The first write side • Fighting the O/RM • Anemic Domain Model – Where did the logic go? • Did we do it wrong? – Layered architecture failed? 26 eBay Inc. confidential

Evolve the code base LET´S SCALE 27 eBay Inc. confidential

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 28 eBay Inc. confidential

CQRS TO THE RESCUE 29 eBay Inc. confidential

Our implementation of CQRS 30 eBay Inc. confidential

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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 33 eBay Inc. confidential

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 34 eBay Inc. confidential

The new platform RabbitMQ ASP.NET MVC Dapper MS SQL Server LINQ2SQL CQRS Nagios jQuery DDD Event Store Entity Framework ADO.NET FAST Memcached Miniprofiler 35 eBay Inc. confidential

Where we ended 36 eBay Inc. confidential

Q&A 37 eBay Inc. confidential

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