When DDD Meets Integration: A Workshop for Practitioners Who've Survived the Spaghetti

At DDD Europe 2025, Karol Skrzymowski and Philipp Kostyra presented Eric Evans with an idea: take the strategic patterns that govern Bounded Contexts inside a system and apply them to the connections between systems. Evans was puzzled. Not dismissive. Genuinely puzzled. The kind of face that says "why hasn't anyone framed it this way before?"

That reaction confirmed what a year and a half of research had already shown them. There is a massive gap between how organisations think about integration and how they think about domain design. This workshop exists to close it.

The Insight

After a decade of DDD Europe, the audience has done Event Storming. They understand Bounded Contexts. They have argued about Aggregates. They can spot an anemic domain model from across a room.

So let's talk about something that doesn't get enough strategic attention: the spaces between systems.

A Bounded Context describes a boundary of a system. Zoom out and treat the system itself as a Bounded Context, and the same strategic patterns apply at the inter-system level. Context Maps. Interaction patterns. Team topologies. The whole lot.

The difference is that this level is usually dismissed as infrastructure. That's the territory that Karol Skrzymowski and Philipp Kostyra have been quietly mapping for the past year and a half, and are promoting it as a first-class citizen.

How This Workshop Was Born

It started, as many good ideas do, in a conference hallway.

Karol is an integration architect with over 14 years of experience designing interoperability across large-scale ecosystems. Philipp works at SAP, where he has spent almost 10 years establishing Domain-Driven Design as a design discipline and is deeply EventStorming-socialised (his wife knows: commands are blue, events are orange, decisions are purple).

They met at DDD Europe 2024. A Polish name, a Polish guy, a hallway conversation that turned into a research project. They figured out that the strategic tools of DDD can be mapped directly to integration patterns: understanding which systems are involved, how they connect, which teams need to interact, and how to discover the politics between them.

The Hidden Cost of Getting Integration Wrong

Sales orders vanishing between systems. A deal worth millions, gone in transit between a CRM and an ERP. Endless point-to-point integrations that nobody fully understands, where every new connection multiplies the risk.

At T-Mobile Poland, Karol's team experienced this first-hand: a system started flooding a JMS queue with messages. In a matter of hours, a queue that sat at a few kilobytes ballooned to nearly a gigabyte. The team running that system had no idea anything was wrong. They only found out through an incident management tool.  By then, Karol's team had already identified the problem, isolated the messages’ source, and raised the incident. That was possible because they had standardised logging and monitoring centralised in the integration platform, and could see every endpoint, every traffic volume, every failed request. In 2014, in Poland, before DevOps was widely established.

The value is there. It just requires investment before you reap the rewards.

Proper integration design unlocks strategic capabilities:

• Reusability: build once, use repeatedly, instead of reinventing point-to-point connections
• Observability: see failures as soon as they appear not when they already cause significant damage
• Security and testability: protect downstream systems from unnecessary traffic or even breach
• Scalability: identify performance bottlenecks from the platform itself

Get it right and development teams spend less time on operations and more time building.

This Is Not an Introductory Workshop

The course uses a fictional company, Polish Pierogi, a food delivery business that Karol and Philipp have "founded" together in an alternative universe after quitting their IT jobs. Participants follow the business as it grows from a simple two-system startup to a full-scale enterprise. Along the way, they learn which architectural style fits which maturity level, and why the wrong choice at the wrong time creates the spaghetti that makes everyone miserable.

The method works from business processes outward. Using tools like Domain Message Flow, participants map flows between teams, identify the patterns, and derive the right technical approach from there. The goal is an end-to-end method: start with the business, finish with a defensible architectural decision.

The prerequisite is honest: you should already know the basics of Event Storming. This is a workshop for practitioners who want to go deeper, not for people still learning the fundamentals.

What You Walk Away With

• A shared vocabulary for integration decisions. The patterns and styles that work across business and technical roles, without relying on constantly misused buzzwords.
• A structured trade-off method. Evaluate event-driven, broker-based, and API-led approaches against your actual business context. Defend your choice to architects, engineers, and stakeholders.
• The ability to read your current landscape. Recognise the signals that an ecosystem has grown without intent: tactical-only decisions, missing rationale, hype-driven style choices. Build the case for making it explicit.
• A reusable playbook. Not theory to file away. A methodology you apply to the next integration project, and the one after that.

What Participants Say

"Building integrations is one of the most challenging parts of enterprise development. This workshop does a great job at discussing both the challenges and suggests actionable techniques to discover robust solutions and reduce the implementation risk."

— David Vydra, Development Expert, SAP, 2025

"This workshop delivered a practical, DDD-led approach to Enterprise Application Integration. Participants compared integration options with clear strengths and weaknesses and practised trade-off and quality-attribute analysis in a hands-on format. The environment was inclusive and engaging, with approachable instructors. Best suited to intermediate and advanced practitioners."

— Ken Bonny, Owner, More than Code BV, 2025

For the DDD Europe Veterans in the Room

If you have been in the DDD community for a few years, you already have the mental models this workshop builds on. What it gives you is the vocabulary and the patterns to apply those models one level up, to the ecosystem around your systems, not just the systems themselves.

Interoperability is no longer an infrastructural afterthought. In today's distributed world, it is a design decision with real business consequences. This workshop treats it as one.

Next Session

20-30 April 2026, online, four half-days across two weeks. Maximum six participants.

Seats are limited by design. Watch Karol and Philipp talk through the ideas in the video, then book your ticket.