Event Sourcing Projections patterns: Deduplication strategies

August 9, 2019 Kacper Gunia

In a typical CQRS/ES system events delivered to projections have At-least-once delivery guarantee and because of that it is usually necessary to implement deduplication in order to achieve idempotency.

Although some of the message queue / streaming platforms claim that they can deliver exactly one semantics the answer to the deduplication problem problem is nuanced and we can’t get away without solving it.

Bootstrapping London DDD Community

July 24, 2016 Kacper Gunia

Couple of months ago, just before the DDD Europe conference a question "Why there is no DDD community in London" struck my mind and didn't let me sleep (literally). If you think about it - it doesn't really make sense - especially that we have a good number of DDD Practitioners (or even book authors) in the city, DDD eXchange is the longest running conference and Skills Matter regularly organises DDD related trainings.

Getting default values from Dictionaries in Swift

July 14, 2015 Kacper Gunia

Swift is around for some time now and introduced interesting constructions that are not widely used in other languages. One of these construction is if let statement that unwraps optionals. Let's consider following example…

Understanding Gang of Four's Facade Design Pattern

November 30, 2014 Kacper Gunia

TL;DR: use Facade Design Pattern to simplify usage of a complex subsystems and reduce number of dependencies your code has

During recent Design Patterns training I've attended at Inviqa (delivered by @_md) we had quite emotional discussion about differences between Facade and Adapter patterns (which are intuitively different but it was hard to understand why). This discussion led me to this blog post and I'd like to summarise our conclusions.

PhpSpec Live Templates for PhpStorm

November 23, 2014 Kacper Gunia

During PhpSpec & PhpStorm webinar recorded together with JetBrains I've mentioned couple of times how Live Templates can speed up your development.

Personally on daily basis I'm using templates I've created for PhpSpec and shared after the webinar but since then I've improved those and would like to share it with you guys.