Book Image

Get Your Hands Dirty on Clean Architecture

By : Tom Hombergs
Book Image

Get Your Hands Dirty on Clean Architecture

By: Tom Hombergs

Overview of this book

Building for maintainability is key to keeping development costs low and processes easy. The second edition of Get Your Hands Dirty on Clean Architecture is here to equip you with the essential skills and knowledge to build maintainable software. With this comprehensive guide, you’ll explore the drawbacks of conventional layered architecture and the advantages of domain-centric styles such as Robert C. Martin's Clean Architecture and Alistair Cockburn's Hexagonal Architecture. Then, you’ll dive into hands-on explanations on how to convert hexagonal architecture into actual code. You'll learn in detail about different mapping strategies between the layers of hexagonal architecture and discover how to assemble the architectural elements into an application. Additionally, you’ll understand how to enforce architecture boundaries, which shortcuts produce what types of technical debt, and how, sometimes, it is a good idea to willingly take on those debts. By the end of this second edition, you'll be armed with a deep understanding of the hexagonal architecture style and be ready to create maintainable web applications that save money and time.
Table of Contents (13 chapters)

The "Full" Mapping Strategy

Another mapping strategy is what I call the "full" mapping strategy, sketched in the following figure:

Figure 8.3: With each operation requiring its own model, the web adapter and application layer each map their model into the model expected by the operation they want to execute

This mapping strategy introduces a separate input and output model per operation. Instead of using the domain model to communicate across layer boundaries, we use a model specific to each operation, such as SendMoneyCommand, which acts as an input model to the SendMoneyUseCase port in the figure. We can call those models "commands," "requests," or something similar.

The web layer is responsible for mapping its input into the command object of the application layer. Such a command makes the interface to the application layer very explicit, with little room for interpretation. Each use case has its own command with its own fields and validations...