Adam Dymitruk is the creator of event modeling and the CEO and founder of Adaptech Group, a consultancy that builds information systems using event sourcing and event modeling. A software developer with over three decades of experience, Adam is a core contributor to CQRS and event sourcing theory and practice since 2008, a top 0.1% Stack Overflow contributor, and one of the original voices in the ALT.NET movement. He’s currently writing the definitive book on event modeling, with a companion booklet due out first.
Episode Description
Why do we keep building software that breaks every time we add a feature? And what if there were a way to describe a system so clearly that business people, designers, and developers could all work from the same blueprint?
In this conversation, Adam Dymitruk traces a path from the rebellion of the ALT.NET movement in the mid-2000s through the rise of domain-driven design, the discovery of event sourcing, and the creation of event modeling, a notation and process for describing information systems that has quietly become one of the most practical innovations in modern software design. Along the way, Adam and Dave revisit shared history: the nHibernate Mafia, the fight against sealed classes, the moment when Martin Fowler’s 2005 article on event sourcing planted a seed that would take years to fully grow, and the community of developers who decided they’d rather take care of each other than wait for permission from Microsoft.
The heart of the episode is Adam’s case for why event sourcing and event modeling eliminate entire categories of problems that most teams accept as inevitable: the hockey-stick cost curve, the coupling that turns codebases into houses of cards, the schema migrations that become existential crises, and the tech debt that accumulates because every new feature has to touch code that already works. Adam explains how Adaptech Group has built its business on fixed-cost contracts and free bug fixes, not as a loss leader but because the architecture genuinely makes it possible. The conversation closes with Adam’s view on AI as the next irreversible point of no return, why event modeling provides exactly the kind of specification that AI needs to generate good code, and a first look at the two books he’s writing to bring this work to a wider audience.
Links & Resources
Guest Links
Adaptech Group — Adam’s consultancy
Event Modeling — the official site for the event modeling methodology
Event Modeling: What is it? — Adam’s original 2019 article
Books & Articles Mentioned
Understanding Eventsourcing by Martin Dilger — the first book combining event modeling and event sourcing
Domain-Driven Design by Eric Evans — the influential “blue book” both Adam and Dave reference on multiple occasions
Domain-Driven Design Reference by Eric Evans — the companion booklet that Adam credits as a model for his own booklet approach
Working Effectively with Legacy Code by Michael Feathers — cited by Adam as a model for the reference-pattern format of his upcoming book
“Event Sourcing” by Martin Fowler — the December 2005 article that introduced Adam to event sourcing
Tools, Frameworks & Concepts
Event Sourcing — an architectural pattern of storing state changes as an immutable sequence of events
CQRS (Command Query Responsibility Segregation) — a pattern for separating read and write models
Domain-Driven Design — Eric Evans’ approach to software development that became the intellectual home for event sourcing in the .NET world
Event Storming — Alberto Brandolini’s workshop format that influenced event modeling’s collaborative approach
ALT.NET — the mid-2000s .NET developer community that championed open source, TDD, and better practices
Test-Driven Development (TDD) — discussed at length, including Adam’s controversial position that event sourcing eliminates the need for it
Cucumber — BDD testing tool that Adam used before discovering that events themselves serve as specifications
Storyteller — Jeremy Miller’s graphical DSL testing framework for .NET that Adam used extensively for specification by example
NUnit — Charlie Poole’s open source .NET testing framework, a counterpart to Java’s JUnit
nHibernate — the open source .NET ORM ported from Java’s Hibernate; central to ALT.NET’s origin story (originally nicknamed the “nHibernate Mafia”)
Dynamic Consistency Boundary — an evolution beyond DDD aggregates for managing consistency in event-sourced systems
Specification by Example / Behavior-Driven Development — the testing and specification approaches that preceded event modeling
Open/Closed Principle — referenced by Adam in the context of event sourcing’s add-only architecture
Cursor — AI coding tool Adam used to demonstrate that event model screenshots produce correct implementations on the first try
Unix Philosophy — invoked by Dave to describe the component architecture that event sourcing enables: many specific tools that each do one thing well
People Referenced
Greg Young — CQRS and event sourcing pioneer, longtime collaborator
Scott Bellware — Founder of the Eventide project and co-founder of ALT.NET
Martin Fowler — author of the 2005 event sourcing article
Eric Evans — author of Domain-Driven Design
Michael Feathers — author of Working Effectively with Legacy Code (also former podcast guest)
Alberto Brandolini — creator of Event Storming
Martin Dilger — author of Understanding Eventsourcing
Jeremy Miller — creator of the Storyteller testing framework
Mike Stockdale — creator of SpecSharp, from Calgary
Charlie Poole — creator of NUnit
Sebastian Lambla — .NET open source contributor whose work was famously overwritten by Microsoft
Scott Hanselman — referenced in the context of ALT.NET’s reach into the Microsoft community
Topics Discussed
The ALT.NET Rebellion and Finding Your People
Adam and Dave open by tracing their shared history in the ALT.NET movement, a community of .NET developers who pushed back against Microsoft’s top-down approach to software development in the mid-2000s. What started as frustration with sealed classes, proprietary tooling, and the “embrace, extend, extinguish” mentality became a proving ground for open source, test-driven development, and the architectural ideas that would shape both of their careers.
Key points:
ALT.NET (originally nicknamed the “nHibernate Mafia”) was born from developers needing to take care of each other because Microsoft wasn’t supporting the open source community
The community brought together TDD practitioners, open source advocates, and domain-driven design enthusiasts, creating the conditions for ideas like event sourcing to gain traction
Figures like Sebastian Lambla experienced the worst of Microsoft’s competitive stance, having their open source work overwritten overnight by official Microsoft alternatives
Both Adam and Dave credit ALT.NET as the environment where their points of view coalesced, particularly around DDD and event-driven architectures
From Domain-Driven Design to Event Sourcing
The conversation traces how DDD provided the intellectual soil for event sourcing to take root, beginning with Martin Fowler’s 2005 article and evolving through Adam’s own experiments writing his first event store in 2009. Adam describes the shift from thinking about domain models and objects to thinking about state changes, facts, and immutable ledgers.
Key points:
Adam wrote his first production event store in 2009 as a single page of C# code, proving the simplicity of the approach
The key insight: treat information the way accountants treat money, with full accountability and no erasures
Specification by example and BDD, while valuable stepping stones, became unnecessary once events themselves served as human-readable specifications
The community continues to evolve; practices like dynamic consistency boundaries are replacing traditional DDD aggregates, and event versioning through upcasters is giving way to handling multiple event versions directly in read models
Event Modeling: The Swiss Army Knife
Adam delivers his pitch for event modeling: a notation and process for describing information systems that looks like a sideways storyboard, captures state changes as events in plain English, and deliberately excludes implementation details. Born from the realization that his team at Adaptech was already doing something distinctive (they just thought they were doing BDD really well), event modeling was first formally written down at the Event Storming summit in 2018.
Key points:
Event modeling uses only three moving pieces and four patterns based on two ideas; it takes minutes to explain and the rest is learned in practice
No branching logic in workflows; the notation sticks to a storyline by example because human minds remember stories far better than they remember graphs
The UX/UI is a first-class citizen in an event model, not an afterthought, because every system is ultimately built for human beings looking at an interface
Event modeling functions as a blueprint comparable to architectural plans for a building: the plumber, the carpenter, and the electrician all work from the same document
The Flat Cost Curve and Why Coupling Is the Real Enemy
Adam makes a direct business case for event sourcing and event modeling: Adaptech Group offers fixed-cost contracts and fixes bugs for free. This isn’t charity; it’s a direct consequence of an architecture where new features don’t touch existing code, coupling is managed by design, and the immutable event ledger serves as the single source of truth.
Key points:
The “hockey stick” cost curve in traditional software comes from coupling: shared canonical models, CRUD operations that affect multiple consumers, and abstractions that break everything when they change
Event sourcing inverts this by using multiple purpose-built read models that each have exactly what they need, coordinated by an undisputed set of events
Schema migrations effectively disappear because new versions of data and old versions coexist naturally
The biggest conceptual barrier is the industry’s attachment to a single canonical model, an idea sold from academia through inheritance hierarchies that doesn’t mirror how real-world information systems have operated for centuries
AI as the Next Point of No Return
The conversation turns to AI, which Adam frames alongside the Commodore 64, the internet, email, Linux, and event sourcing itself as an irreversible “aha moment.” His own turning point was watching ChatGPT generate CSS animations in seconds that would have taken him three hours, and he sees event modeling as the missing link that gives AI the specification quality it needs to generate real systems.
Key points:
AI’s impact is comparable to how Google gave us access to everything, but AI gives us the ability to make sense of everything instantly
The bottleneck is shifting left to planning, which is exactly where event modeling lives: providing clear, structured specifications that AI can execute against
Adam demonstrated early success pasting event model screenshots into Cursor’s chat window and getting correct unit tests and implementations on the first try, even with less capable models
The Pandora’s box framing: you can’t uninvent the internet, and you can’t uninvent AI inference; the question is whether your specifications are good enough to benefit from it
Two Books and What’s Next
Adam closes with an update on his long-anticipated event modeling book, which is actually two books. Inspired by Eric Evans’ companion booklet to the DDD blue book and Michael Feathers’ reference-pattern format in Working Effectively with Legacy Code, Adam is releasing a concise booklet first, followed by a comprehensive reference book.
Key points:
The booklet comes first, designed to be immediately applicable, covering why event modeling exists, its core pieces, and the rules for assembling them
The full book will include the backstory and motivations, plus a library of reference patterns covering the top 90% of common information system scenarios (sign-up flows, payment integrations, checkout carts, pub/sub patterns, and more)
Adam deliberately delayed the book because he never wanted event modeling to require a book to understand, a lesson drawn directly from watching the DDD book’s intimidating thickness reduce its effective adoption
Martin Dilger’s Understanding Eventsourcing already covers event sourcing using event modeling throughout, giving the community a practical resource while the definitive event modeling book takes shape
Hard Boiled Software is hosted by Dave Laribee.
