Modular Monoliths and Other Facepalms - Kevlin Henney - NDC London 2026

Value of the Information & Strength of the Argument

The talk provides valuable insights into the cyclical nature of software architecture trends, backed by historical references and personal anecdotes. Henney’s argumentation is solid, using examples like the misapplication of microservices and the misinterpretation of object-oriented programming. He effectively demonstrates that modularity is not new but often forgotten, and he stresses the importance of information hiding and clear boundaries. The talk is persuasive, though it relies more on experience than empirical evidence, which is typical for expert opinion talks.

Scientific Rigor, Source Quality, Title Accuracy

Henney references key historical works such as Parnas’s 1972 paper on modular decomposition and Alan Kay’s definition of object-oriented programming, which adds credibility. However, he does not provide formal citations or URLs, making it harder to verify. The title accurately reflects the content, and the talk is well-structured. The speaker’s expertise is evident, but the lack of concrete sources is a minor weakness.

The title accurately reflects the content, which critiques the misuse of the term 'modular monolith' and highlights the cyclical nature of architectural trends.

8/10

The talk is based on the speaker's extensive experience and references historical sources (Parnas, Alan Kay, Unix philosophy) without formal citations. The arguments are well-reasoned and align with established software engineering principles, but lack empirical data or systematic review.

Markers derived by PSI from the transcript: the creator did not define chapters.

• 02:00Introduction and setup: talk about monoliths and the purpose of the talk.
• 05:00Discussion on the distribution of knowledge and the 'lucky 10,000' concept.
• 10:00Explanation of the term 'monolith' and its negative connotations.
• 15:00Calibration stories: examples of different perceptions of code size.
• 20:00Definition of microservices and the importance of contracts.
• 25:00Alan Kay's quote on object-oriented programming and its misinterpretation.
• 30:00Unix philosophy and Parnas's principles of modularity.
• 35:00Historical overview of modularity from Smalltalk to modern times.
• 40:00Discussion on the importance of understanding underlying principles.
• 45:00Conclusion and call to action: learn from history and avoid facepalms.

• NDC Conferences — Conference organizer and source of the talk.
• NDC London — Specific conference where the talk was given.

• Building Microservices by Sam Newman — Book that recommends starting with a well-structured monolith, aligning with the talk's message.

• Microservices: A Definition of This New Architectural Term — While not directly contradicting, it presents microservices as a distinct style, which the talk critiques as a rebranding of old ideas.

• ndclondon.com