Nick Tune on Domain-Driven-Design

Today, Youtube recommend this talk by Nick Tune to me:

I had actually never heard of Nick Tune nor the NDC Conferences before, but the title certainly struck a chord with me. For one, I am currently reading the book Team Topologies and I recently started learning about Domain-Driven Design. So overall, good job Youtube alogrithm!

Now, the talk itself became most interesting to me in its last part, the part about indentifying and strengthening your company’s core domains. The first part was mostly about Event Storming, a technique that Nick seems to be using a lot as a consultang. The second part was a short introduction to Team Toplogies. The concept of the independent service heuristics sounded quite interesting and worth mentioning here.

So for the rest of this post, I will mostly collect links that have been mentioned in the talk and maybe summarize some of the techniques that are mentioned there. I really liked the fact that Nick Tune and team have github organization called Domain-Driven Design Crew.

Independent Service Heuristics

The Independent Service Heuristics (ISH) are rules-of-thumb (clues) for identifying candidate value streams and domain boundaries by seeing if they could be run as a separate SaaS/cloud product. Based on some of the ideas in the book Team Topologies by Matthew Skelton @matthewskelton and Manuel Pais @manupaisable.

This is essentially a checklist, or question catalogue, of 20-30 items that you shold try to answer. The more “yes” or “probably” answers, the greater the chance that you have found a good candidate for being a separate stream of change.

Core Domain Charts

As mentioned above, the third part of the talk is mostly about applying Core Domain Charts to different case studies and identifying patterns and anti-patterns wihin the framework.

Core Domain Charts is a set of visualization techniques that is available as a github repository on the Domain-Driven Design Crew’s github. It’s essentially using 2 types of charts, one where business domains are sorted by the axes “Business Differntiation” and “Model Complexity”,

and a seocond chart, more for the purpose of finding out about useful migration paths, where the axes are “Business Differentiation” and “Migration Complexity”.

Nick Tune identifies 3 main areas in the Core Domain Chart: The acutal core domain (defined by highest business differentiation, the supporting domain (also called table stakes features) and then, lastly, generic subdomains (things that you typically want to by off the shelf where possible).

The main strategies to improve on your subdomains is by exploiting (find complexity that can increase differentiation, i.e. migrate towards top right) and eliminate (find unnecessary complexity and get rid of it if it doesn’t harm your business differentiation, i.e. migrate towards bottom wherever you are on the x-axis).

Some strategies he mentioned in the talk:

  • Watch out for Hidden domains
  • Decouple supporting domains for fast flow in core domains
  • Put your efforts into a Decisive core
  • Watch out for indefensible cores
  • Try to find a revenue stream for Big Bet Future Cores
  • Take your High-leverage Supporting Subdomains seriously
  • Suspect Supporting: Try to reduce the complexity in those, maybe their codebaes has just grown old over time

The techniques summarized in this repository seem to be an elaboration on the chapter “Distillation for Strategic Design” in Eric Evans’ book Domain-Driven Design.

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