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)

Responsibilities of a Web Adapter

What does a web adapter actually do? Let's say we want to provide a REST API for our BuckPal application. Where do the responsibilities of the web adapter start and where do they end?

A web adapter usually does these things:

  1. Maps HTTP requests to Java objects
  2. Performs authorization checks
  3. Validates input
  4. Maps input to the input model of the use case
  5. Calls the use case
  6. Maps the output of the use case back to HTTP
  7. Returns an HTTP response

First of all, a web adapter must listen to HTTP requests that match certain criteria, such as a certain URL path, HTTP method, or content type. The parameters and the content of a matching HTTP request must then be deserialized into objects we can work with.

Commonly, a web adapter then does an authentication and authorization check and returns an error if it fails.

The state of the incoming objects can then be validated. But haven't we already discussed input validation as a responsibility...