The Hexagonal - Ports & Adapters Architecture | Alistair Cockburn | SAG 2025

In this 45-minute keynote, Alistair Cockburn – co-author of the "Agile Manifesto" and creator of "Hexagonal Architecture" (Ports & Adapters) –explains how and why this architectural style emerged, using real projects, real failures, and real code.

Starting from a simple challenge—can your application run without a UI or a database?—Alistair walks through the core ideas of Ports & Adapters step by step. He shows how placing interfaces inside the application, keeping adapters outside, and treating tests as the first user of the system can radically improve testability, flexibility, and long-term maintainability.

Along the way, he shares stories from decades of experience: systems broken by tight coupling, painful technology shifts, and the practical lessons that led to the hexagonal model in the first place. Expect concrete Java and Ruby examples, UML diagrams, folder structure advice, and candid opinions on common mistakes.

In this talk, you’ll learn:
✅ What Hexagonal Architecture really is (and why it’s better called Ports & Adapters)
✅ Why adapters always live outside the application boundary
✅ The difference between driving and driven ports
✅ How tests act as the first and most important user of your app
✅ How to prevent business logic from leaking into UI or infrastructure code
✅ Why folder structure matters more than most people think
✅ How Ports & Adapters compares to traditional layered architectures
✅ The historical problems and real systems that shaped the pattern

This keynote is ideal for developers, architects, and teams building long-lived systems who want software that can evolve—new databases, new UIs, new technologies—without rewriting the core.
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Resources mentioned in the Keynote:
https://hexagonalarchitecture.org/
https://jmgarridopaz.github.io/content/resources.html
https://jmgarridopaz.github.io/
https://tangible-concepts.de
https://github.com/jmgarridopaz/bluezone
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Sources & Additional Information:

Here are some articles and videos about hexagonal architecture / ports a
1 The original article by Alistair Cockburn:https://alistair.cockburn.us/hexagonal-architecture/
2 The new article "Component + Strategy generalizes Ports & Adapt https://alistaircockburn.com/Articles/Component-Strategy-genera
3 The expanded explanation website by Juan Manuel Garrido de Pahttps://jmgarridopaz.github.io/
4 El articulo original de Alistair Cockburn en español (traducción de https://jmgarridopaz.github.io/content/arquitecturahexagonal.html
5 Slides from a 2009 talk by Alistair Cockburn, with explanation and https://web.archive.org/web/20140329202802/http://alistair.cockb
6 Alistair interviewed by Rodrigo Branas, talking about it:|https://www.youtube.com/watch?v=AOIWUPjal60
7 1st video explanation by Alistair Cockburn: "Alistair in the Hexagoi https://www.youtube.com/watch?v=th4AgBcrEHA
8 2nd video explanation by Alistair Cockburn, with programming by https://www.youtube.com/watch?v=Sc B6dQ6di0
9 Short videos just with drawings, by Juan Manuel Garrido de Paz:https://jmgarridopaz.github.io/content/hapills.html
10 Video programming example by Thomas Pierrain:https://www.youtube.com/watch?v=iALcE8BPs94 andhttps://www.youtube.com/watch?v=DAe0Bmcyt-4
11 Sample code on GitHub by Alistair Cockburn:https://github.com/totheralistair/SmallerWebHexagon
12 Sample code on GitHub by Juan Manuel Garrido de Paz:https://github.com/jmgarridopaz/bluezone
13 Case study, article from Netflix: "Ready for changes with Hexagon https://netflixtechblog.com/ready-for-changes-with-hexagonal-arc
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Save the date for iSAQB Software Architecture Gathering 2026, from November 16 to 19, 2026 in Berlin: https://sag.isaqb.org

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Video Production @Kameramensch-Filmproduktion for iSAQB GmbH
Executive Producer: Johannes Klemt
1st Camera OP: Nico Schallat
2nd Camera OP: Vladimir Traut
Stage, Light & Sound: Kingsize.Events

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