Implementing Validation

TL;DR use Command objects to modify objects of Domain Model check basic validation rules on these Commands use validation framework for checking rules on Commands implement constraints that are "interesting" from business perspective inside Domain Model as part of the behavior without any validation framework Constraint scopes

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Where’s The Force in the Revolution?

It was almost eight moons ago when Obi-Wan first noticed the unusually high midichlorian levels in my blood and decided to give me a chance to join the International Money Transfer Revolution. He, together with Master Yoda, have trained me well, to harness the raw energy of 'The Force' so

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Fun with BigDecimal

So you've got the idea for the next big FinTech company. Since this is about money, you decided to use a serious language, Java. And for representing your currency amounts, BigDecimal seemed like a safe choice. Now time for the small print... BigDecimal.equals() does what?? A big trap to

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The Ulf way of doing hackathons

[pronounced: Ʊlf] Gather a bunch of smart engineers - put them in an isolated room for 48 hours - sprinkle with some clever ideas - then have them code until they’re exhausted... this is known as the 'textbook' way of doing vanilla hackathons. Then there’s the 'Ulf' way…

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Demystifying product interviews

TransferWise engineering interview process consists of several steps which can be broadly outlined as following: Screening One or two technical interviews Product interview VP engineering and Founder interview The third step in the process - product interview is somewhat unorthodox and may leave some candidates puzzled and struggling. To make

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