Building Microservices: Designing Fine-Grained Systems

by Sam Newman

In this chapter, you’ve learned a bit about what makes a good service, and how to find seams in our problem space that give us the dual benefits of both loose coupling and high cohesion. Bounded contexts are a vital tool in helping us find these seams, and by aligning our microservices to these boundaries we ensure that the resulting system has every chance of keeping those virtues intact. We’ve also got a hint about how we can subdivide our microservices further, something we’ll explore in more depth later. And we also introduced MusicCorp, the example domain that we will use throughout this book. The ideas presented in Eric Evans’s Domain-Driven Design are very useful to us in finding sensible boundaries for our services, and I’ve just scratched the surface here. I recommend Vaughn Vernon’s book Implementing Domain-Driven Design (Addison-Wesley) to help you understand the practicalities of this approach. Although this chapter has been mostly high-level, we need to get much more technical in the next. There are many pitfalls associated with implementing interfaces between services that can lead to all sorts of trouble, and we will have to take a deep dive into this topic if we are to keep our systems from becoming a giant, tangled mess.