Barry O'Reilly

Barry O’Reilly is a Software Architect, researcher, and the inventor of Residuality Theory, a groundbreaking approach to software design that applies complexity science and philosophy to help teams build systems that survive the unexpected.

He is the Founder of Black Tulip Technology and a Ph.D. candidate in Complexity Science and Software Engineering at The Open University. His research sits at the intersection of philosophy, complexity theory, and software architecture, fields that rarely speak to each other, and that Barry has spent years forcing into productive conversation.Before founding Black Tulip Technology, Barry held Chief Architect positions at Microsoft and other global software companies, served as Worldwide Lead for the Microsoft Solutions Architecture Community, and was a startup CTO. He also founded the Swedish Azure User Group. Across these roles he accumulated a practitioner’s understanding of what happens when architectural decisions meet the real world, with its market shifts, organisational friction, and systems that must evolve long after the original design intent has dissolved.

That experience became the engine behind Residuality Theory. Rather than designing systems around what we predict will happen, Residuality Theory asks architects to start from stress: what conditions could this system face? What residues (the components that survive and adapt) should we build in? The approach draws on complexity science, attractor network theory, and philosophy of representation to produce a lightweight, mathematically grounded set of tools for navigating uncertainty. The result is architecture that is not merely robust, but antifragile: designed to improve under pressure rather than simply withstand it.

His work has been published by Cutter Consortium, one of the most authoritative research publications in the field of enterprise technology.
Residuality Theory has brought Barry international recognition, and today it is possible to attend his talks at leading European conferences such as GOTO Copenhagen, NDC Oslo, and DDD Europe. His Advanced Software Architecture with Residuality Theory Workshop is frequently sold out.

Books

Barry O’Reilly is the author of two books:

• Residues: Time, Change, and Uncertainty in Software Architecture – The hands-on guide to applying Residuality Theory in real projects.
• The Architect’s Paradox: Uncertainty and the Philosophy of Software Architecture – A deeper philosophical examination of why architecture is fundamentally about managing what we cannot know.

His two books give architects both the practical toolkit and the intellectual foundation:

Residues: Time, Change, and Uncertainty in Software Architecture		The Architect’s Paradox

Articles

• Residuality and Representation: Toward a Coherent Philosophy of Software Architecture
• Residuality Theory for Antifragile Software Architecture
• Residuality Theory: Mastering Software Architecture

Videos e talks

• Barry O’ Reilly: the playlist with some of him talks
• Listen to the interview with Barry O’Reilly on Spotify

Contact Barry

Get in touch if you’d like to arrange a conversation with Barry O’Reilly and explore together how we can support your project and your team.