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Software Design

Domain Modeling Gone Wrong – Part 1

How do you model a complex domain? In domain-driven design, you might think about entities, value objects, and aggregates when domain modeling. But how are you defining those? I will go over what a common modeling approach is but is backward. Let me explain why. YouTube Check out my YouTube channel, where I post all kinds of content accompanying my posts, including this video showing everything in this post. Ugh, Aggregates, Entities, and Value Objects Typical advice is to figure out what your aggregates are. You define entities and value objects and then group them together to define aggregates. Aggregates are a… Read More »Domain Modeling Gone Wrong – Part 1

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.