CQRS by Example
CQRS by Example
Command-Query Responsibility Segregation is an architectural style for developing applications that split the Domain Model in Read and Write operations in order to maximize semantics, performance, and scalability. What are all the benefits of CQRS? What are the drawbacks? In which cases does it worth applying it? How does it relate to Hexagonal Architecture? How do we properly implement the Write Model and Read Models? How do we keep in sync both sides? What are the following steps to move towards Event Sourcing? This book will answer all these questions and many more, guided through lots of practical examples. Brought to you by the same authors behind "Domain-Driven Design in PHP".
About the Book
Four years have passed since our first publication, we established what we think is a solid ground for DDD building blocks and Hexagonal Architecture. It is time to explore how to solve the limitations some projects may face at scale.
We think CQRS is the next natural step forward and we want to guide you through it.CQRS is usually discussed along with Event Sourcing, a pattern where application state is a projection of the Domain Events that happen through its lifetime. Event Sourcing relies on having a stream of Domain Events to reconstitute state. Something convenient for operations that modify the state of the application, known as Commands; however, querying the system requires some special mechanisms that aren't that trivial. We can say than in Event Sourced systems CQRS is mandatory in order to generate the required information to be able to query later, but the opposite isn't true. We can develop a CQRS system without Event Sourcing, so worry not, this book won't cover Event Sourcing.
In this book, we'll explore Hexagonal Architecture drawbacks, and we'll dive into CQRS by exploring plenty of real examples that you can use in your projects. Even though code examples are written in PHP, the patterns and techniques described in this book are applicable to any programming language and likely any paradigm you may be using. We can't thank you enough for purchasing this book and be an active contributor of Domain-Driven Design, Hexagonal Architecture, and CQRS!
Table of Contents
-
Preface
- First Book: Domain-Driven Design in PHP
- DDD acceptance has rapidly grown
- Second Book: CQRS by Example
- Who Should Read This Book
- Summary of Chapters
- Code, Typos, and Examples
- Slack Channel
-
Acknowledgements
- Cover
- Contributors
-
About the Authors
- Carlos Buenosvinos
- Christian Soronellas
- Keyvan Akbary
-
CQRS and Domain-Driven Design
- What is all the fuzz about?
- Why Domain-Driven Design Matters
- The Three Pillars of Domain-Driven Design
- Considering Domain-Driven Design
- The Tricky Parts
- Wrap-Up
-
A Journey Towards CQRS
- Introducing Cheeper, a Twitter Clone
- Architectural Styles
- A brief analysis
- Hexagonal Architecture Potential Limitations
- Wrap-Up
-
Anatomy of CQRS
- Cheeper Use Case Analysis
- Cheeper à la CQRS
- CQRS Overview
- Other CQRS Components
- Two Sides Of The Same Coin
- The Command Side
- The Query Side
- Syncing the Command and Query sides
- Wrap-Up
-
Command Side and the Write Model
- Commands
- Command Handler
- Command Bus
- Plumbing all together
- Wrap-Up
- The End
Authors have earned$9,883,643writing, publishing and selling on Leanpub, earning 80% royalties while saving up to 25 million pounds of CO2 and up to 46,000 trees.
Learn more about writing on Leanpub
The Leanpub 45-day 100% Happiness Guarantee
Within 45 days of purchase you can get a 100% refund on any Leanpub purchase, in two clicks.
See full terms
Free Updates. DRM Free.
If you buy a Leanpub book, you get free updates for as long as the author updates the book! Many authors use Leanpub to publish their books in-progress, while they are writing them. All readers get free updates, regardless of when they bought the book or how much they paid (including free).
Most Leanpub books are available in PDF (for computers), EPUB (for phones and tablets) and MOBI (for Kindle). The formats that a book includes are shown at the top right corner of this page.
Finally, Leanpub books don't have any DRM copy-protection nonsense, so you can easily read them on any supported device.
Learn more about Leanpub's ebook formats and where to read them
Top Books
C++ Best Practices
Jason TurnerLevel up your C++, get the tools working for you, eliminate common problems, and move on to more exciting things!
OpenIntro Statistics
David Diez, Christopher Barr, Mine Cetinkaya-Rundel, and OpenIntroA complete foundation for Statistics, also serving as a foundation for Data Science.
Leanpub revenue supports OpenIntro (US-based nonprofit) so we can provide free desk copies to teachers interested in using OpenIntro Statistics in the classroom and expand the project to support free textbooks in other subjects.
More resources: openintro.org.
Functional Design and Architecture
Alexander GraninSoftware Design in Functional Programming, Design Patterns and Practices, Methodologies and Application Architectures. How to build real software in Haskell with less efforts and low risks. The first complete source of knowledge.
R Programming for Data Science
Roger D. PengThis book brings the fundamentals of R programming to you, using the same material developed as part of the industry-leading Johns Hopkins Data Science Specialization. The skills taught in this book will lay the foundation for you to begin your journey learning data science. Printed copies of this book are available through Lulu.
C++20
Rainer GrimmC++20 is the next big C++ standard after C++11. As C++11 did it, C++20 changes the way we program modern C++. This change is, in particular, due to the big four of C++20: ranges, coroutines, concepts, and modules.
I am a Software Engineer and I am in Charge
Alexis Monville and Michael DoyleI am a Software Engineer and I am in Charge is a real-world, practical book that helps you increase your impact and satisfaction at work no matter who you work with.
In the book, we will follow Sandrine, a fictional character who learns to think in a new way enabling her to take a different course of action.
Atomic Kotlin
Bruce Eckel and Svetlana IsakovaFor both beginning and experienced programmers! From the author of the multi-award-winning Thinking in C++ and Thinking in Java together with a member of the Kotlin language team comes a book that breaks the concepts into small, easy-to-digest "atoms," along with exercises supported by hints and solutions directly inside IntelliJ IDEA!
Invest In Digital Health - The Medical Futurist's Guide
Dr. Bertalan MeskoArtificial Intelligence and Digital Health are booming. In this book, we explain why now it's a good time to invest in Digital Health and give recommendations on where to invest by looking at the top 24 technological trends we find the most promising.
The Hundred-Page Machine Learning Book
Andriy BurkovEverything you really need to know in Machine Learning in a hundred pages.
Mastering STM32
Carmine NovielloWith more than 600 microcontrollers, STM32 is probably the most complete ARM Cortex-M platform on the market. This book aims to be the first guide around that introduces the reader to this exciting MCU portfolio from ST Microelectronics and its official CubeHAL.
Top Bundles
- #1
Software Architecture for Developers: Volumes 1 & 2 - Technical leadership and communication
2 Books
"Software Architecture for Developers" is a practical and pragmatic guide to modern, lightweight software architecture, specifically aimed at developers. You'll learn:The essence of software architecture.Why the software architecture role should include coding, coaching and collaboration.The things that you really need to think about before... - #2
CCIE Service Provider Ultimate Study Bundle
2 Books
Piotr Jablonski, Lukasz Bromirski, and Nick Russo have joined forces to deliver the only CCIE Service Provider training resource you'll ever need. This bundle contains a detailed and challenging collection of workbook labs, plus an extensively detailed technical reference guide. All of us have earned the CCIE Service Provider certification... - #3
The Future of Digital Health
6 Books
We put together the most popular books from The Medical Futurist to provide a clear picture about the major trends shaping the future of medicine and healthcare. Digital health technologies, artificial intelligence, the future of 20 medical specialties, big pharma, data privacy and how technology giants such as Amazon or Google want to conquer... - #4
Cisco CCNA 200-301 Complet
4 Books
Ce lot comprend les quatre volumes du guide préparation à l'examen de certification Cisco CCNA 200-301. - #5
CCDE Practical Studies (All labs)
3 Books
CCDE lab - #6
"The C++ Standard Library" and "Concurrency with Modern C++"
2 Books
Get my books "The C++ Standard Library" and "Concurrency with Modern C++" in a bundle. The first book gives you the details you should know about the C++ standard library; the second one dives deeper into concurrency with modern C++. In sum, you get more than 600 pages full of modern C++ and about 250 source files presenting the standard library... - #7
Modern Management Made Easy
3 Books
Read all three Modern Management Made Easy books. Learn to manage yourself, lead and serve others, and lead the organization. - #8
Linux Administration Complet
4 Books
Ce lot comprend les quatre volumes du Guide Linux Administration :Linux Administration, Volume 1, Administration fondamentale : Guide pratique de préparation aux examens de certification LPIC 1, Linux Essentials, RHCSA et LFCS. Administration fondamentale. Introduction à Linux. Le Shell. Traitement du texte. Arborescence de fichiers. Sécurité... - #9
Programming with Ease
3 Books
Alle drei Bände der Serie Programming with Ease in einem Paket. Darin findest du alles, was ich dir zu den wichtigsten Phasen der Softwareentwicklung im Hinblick auf Clean Code Development für langfristig hohe Produktivität sagen kann.Im Band Slicing findest du die Anforderungsanalyse im Rahmen eines iterativ-inkrementellen Vorgehensmodells aus... - #10
Vagrant Ansible
2 Books
Unveil the power of Ansible and Vagrant with this bundle at a special price. You'll have everything you need to get started with Vagrant - learn the basics and how to create your virtual development environments, using Ansible as provisioner! About Vagrant Cookbook Vagrant Cookbook is a complete guide to get started with Vagrant and create your...