Backend design like you've never seen it before - a guide to building SOLID ASP.NET Core web apps that stand the test of time. Featuring more Minimal APIs, more testing, a new e-commerce project, and the modular monolith! Purchase of the print or Kindle book includes a free PDF eBook. Key Features Learn multiple ways to organize your application code and become a more flexible ASP.NET Core developer Explore hands-on design patterns, learn architectural principles, and how to sidestep anti-patterns Refactor code toward modern application design, such as feature-based vertical slice and clean architecture Book Description This unique ASP.NET Core book will fill in the gaps in your REST API and backend designs. Learn how to build robust, maintainable, and flexible apps using Gang of Four (GoF) design patterns and modern architectural principles. This new edition is updated for .NET 8 and focuses exclusively on the backend, with new content on REST APIs, the REPR pattern, and building modular monoliths. You'll start by covering foundational concepts like REST, the SOLID principles, Minimal APIs, dependency injection in .NET, and other ASP.NET Core 8 mechanisms. Then, you'll learn to develop components using design patterns, including many from the GoF. Finally, you'll explore organizing your application code with patterns that vary from layers to feature-oriented vertical slice designs, covering CQS and a deep dive into microservices along the way. A brand-new e-commerce project at the end of the book will tie it all together. This how-to guide will teach you how to assemble your own APIs from building blocks, to suit whatever real-world requirements you may have. What you will learn Apply the SOLID principles for building flexible and maintainable software Test your apps effectively with automated tests, including black-box testing Embark on mastering ASP.NET Core dependency injection Work with GoF design patterns including strategy, decorator, facade, and composite Design REST APIs using Minimal APIs and ASP.NET Core MVC Discover layering and the tenets of clean architecture Use feature-oriented techniques as an alternative to layering Explore microservices, CQS, REPR, vertical slice architecture, and many more patterns Who this book is for This book is for intermediate-level ASP.NET Core developers who want to improve their C# app code structure and API design skills. ASP.NET developers who want to modernize their knowledge and enhance their technical architecture skills will also like this book. It's also a good refresher for those in software design roles with more experience looking to update their expertise. A good knowledge of C# programming and a basic understanding of web concepts is necessary to get the most out of this book, though some refreshers are included along the way. Table of Contents Introduction Automated Testing Architectural Principles REST APIs Minimal APIs Model-View-Controller Strategy, Abstract Factory, and Singleton Design Patterns Dependency Injection Application Configuration and the Options Pattern Logging Patterns Structural Patterns Behavioral Patterns Operation Result Pattern Layering and Clean Architecture Object Mappers Mediator and CQS Patterns Getting Started with Vertical Slice Architecture Request-EndPoint-Response (REPR) Introduction to Microservices Architecture Modular Monolith