Clean Architecture

As I join a new company, I often feel like an impostor. After all the interviews, they really seem to know what they’re doing. I’m humbled and ready to learn from the best. On one such occasion, a few days in, I dealt with a production outage and asked the most senior engineer for help. They came to the rescue and casually flipped a value in the database with a manual update.

Do you know the rare feeling when you develop a new application from scratch and can cover all lines with proper tests? I said “rare” because most of the time, you will work with software with a long history, multiple contributors, and not so obvious testing approach. Even if the code uses good patterns, the test suite doesn’t always follow.

In the previous articles, we introduced techniques like DDD Lite, CQRS, and Clean (Hexagonal) Architecture. Even if using them alone is beneficial, they work the best together. Like Power Rangers. Unfortunately, it is not easy to use them together in a real project. In this article, I will show you how to connect DDD Lite, CQRS, and Clean Architecture in the most pragmatic and efficient way.

The authors of Accelerate dedicate a whole chapter to software architecture and how it affects development performance. One thing that often comes up is designing applications to be “loosely coupled”. The goal is for your architecture to support the ability of teams to get their work done—from design through to deployment—without requiring high-bandwidth communication between teams. Accelerate Note If you haven’t read Accelerate yet, I highly recommend it.

Nowadays we can often hear that monolithic architecture is obsolete and responsible for all evil in IT. We often hear that microservices architecture is a silver bullet which helps to kill all this monolithic evil. But you probably know that there are almost no silver bullets in IT and every decision entails trade-offs. One of the most favored advantages of microservices architecture is good modules separation.

Examples are great for learning, so we decided to create a real, open-source, and deployable web application that would help us show the patterns. All chapters follow the same project, refactored over time.