Section 4: Designing at Application Scale

In this section, we enter the realm of application design. Instead of focusing on a smaller part of an application, we look at how we want to design the application itself. We start by looking into layering, which exposes the bases of application design, where we focus on the three most common layers used in layered applications before moving toward the evolution of layering. We explore two ways of modeling the domain model. We then explore a way to encapsulate and lower the burden of layering and model copy before moving on to newer architectural styles, such as vertical slice and microservices.

Each of these chapters could make a book by themselves, so we explore them at a higher level, helping you make more informed decisions when the time to choose an architectural style will arrive. This section is a starting point to further reading, while still filled with useful content, patterns, tips, and technologies to use straight away in your everyday projects.

The goal is to cover as many application-level patterns as possible. The reason is that knowing a little about many techniques helps choose the right method for the job at hand instead of picking the same one every time. Getting better at something is easier when you know where to start, but impossible if you don't know what options are available.

This section comprises the following chapters:

• Chapter 12, Understanding Layering
• Chapter 13, Getting Started with Object Mappers
• Chapter 14, Mediator and CQRS Design Patterns
• Chapter 15, Getting Started with Vertical Slice Architecture
• Chapter 16, Introduction to Microservices Architecture