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 Responsibilities of a Persistence Adapter

Let's have a look at what a persistence adapter usually does:

  1. Takes input
  2. Maps input into a database format
  3. Sends input to the database
  4. Maps database output into an application format
  5. Returns output

The persistence adapter takes input through a port interface. The input model may be a domain entity, or an object dedicated to a specific database operation, as specified by the interface.

It then maps the input model to a format it can work with to modify or query the database. In Java projects, we commonly use the Java Persistence API (JPA) to talk to a database, so we might map the input into JPA entity objects that reflect the structure of the database tables. Depending on the context, mapping the input model into JPA entities may be a lot of work for little gain, so we will talk about strategies without mapping in Chapter 8, Mapping between Boundaries.

Instead of using JPA or another object-relational mapping framework...