Thomas Pierrain

Thomas Pierrain

Bi-temporal Event Sourcing

@tpierrain · France



Co-organizer of the DDD Paris user group, Thomas is an eXtreme Programmer & technical architect obsessed by use cases (Vs. solution-driven approaches). He likes using DDD & TDD to boost his efficiency at work. Advocating the advantages of the Hexagonal architecture since many years (talks, blogposts...), Thomas has recently live-coded with Alistair Cockburn on that topic.

His company 42skillz which aims to help organizations to make software and to work differently, he provides trainings, coaching, consulting about TDD, BDD, legacy code refactoring techniques and DDD with an extra soul.

As Time Goes By… (a Bi-temporal Event Sourcing story)

By Thomas Pierrain

When we started that project for an asset management company (finance), we had difficulties to understand what the business really needed. Despite the various event storming sessions, we struggled during 2 weeks to understand why they needed so much things such as retroactive events, advanced bi-temporality, forecasted "events", etc. It was in the context of an event sourcing (ES) platform and this is our learning story (with chunks of advanced ES patterns). Yet another illustration of the power of modeling, sketches and concrete examples when we need to understand each others.

Distill the Core Domain from Your Legacy App

By Bruno Boucard and Thomas Pierrain

Let's take a very common legacy application: procedural code everywhere, anemic domain logic fully entangled with technical concerns and code. Nothing but classical stuff, right? Our mission for this truly interactive live-coding session will be to identify and extract the core domain logic out of this tar pit in order to add a new feature that has been desperately asked by our business since months.

Last but not least, we will clean the situation for the years to come by properly splitting the domain code from the technical one using the Hexagonal Architecture pattern. Ready to help us in that journey?

The Premier Software Modelling & Design Conference

Missed #DDDEU?

Get tickets for the next edition

Amsterdam, Jan 30 – Feb 2, 2018



More speakers to be announced


Contact us at for sponsor opportunities.