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Derek Comartin

DDD is just giving a 💩 about your Domain

When illustrating domain-driven design (DDD), sample/reference applications do more harm than good. Overall in a vacuum, they’re a net negative. It isn’t easy to convey the complexity and trade-offs made using trivial code examples. Beyond that, the code samples themselves are the wrong starting point. YouTube Check out my YouTube channel, where I post all kinds of content accompanying my posts, including this video showing everything in this post. Where NOT should you start The typical developer path when thinking about DDD is jumping into code. Code samples and demos are great for illustrating patterns or concepts. The problem is when patterns… Read More »DDD is just giving a 💩 about your Domain

Focusing on “Entities” leads nowhere good.

Focusing on data or “entities” can lead you to develop a system that is hard to change and, over time, littered with technical complexity. I will cover why you must think about your system’s behaviors and start being explicit. YouTube Check out my YouTube channel, where I post all kinds of content accompanying my posts, including this video showing everything in this post. Blinded by Data This video/blog was inspired by this post on Reddit. First, why is it fairly obvious that the “microservices” are a teacher, student, etc? That’s the first problem. It’s not obvious at all what “school app” does.… Read More »Focusing on “Entities” leads nowhere good.

What are Business Rules? It’s not this.

What are business rules? Well, they often get confused with trivial validation. I think it’s essential to make the distinction because where you apply business rules and validation will differ and indicate the type of system you’re building. Let me explain and illustrate how you can make the distinction with a simple code example. YouTube Check out my YouTube channel, where I post all kinds of content accompanying my posts, including this video showing everything in this post. Example Let’s immediately start with a very simple code example. Here’s a single method that has two conditions. The first is that if the… Read More »What are Business Rules? It’s not this.