29
.
04
.
2024
11
.
07
.
2022
Ruby on Rails
Domain-Driven Design
Backend
Tutorial

Introduction to DDD in Ruby on Rails

Paweł Strzałkowski
Chief Technology Officer

As a Ruby on Rails community, we have been immune to the changes in the programming world around us for a long time. As if nothing new has been introduced since the beginning of times (or the release of the first version of RoR in 2005). Whereas important and interesting innovations occur all around.

In 2003, Eric Evans released a book titled "Domain-Driven Design: Tackling Complexity in the Heart of Software" which has changed the landscape of many programming technologies. The ideas and techniques promoted by this book are well known among Java, C# or PHP programmers. The approach is used to build better and more reliable software. Especially at the enterprise level, where the attention to detail is at its peak.

Eric Evans wasn't the only person responsible for the global DDD boom. His initial book is often referred to as "The Blue Book", but there is also "The Red Book" or in fact "Implementing Domain-Driven Design" by Vaughn Vernon. These two figures, alongside others who grew out of the Smalltalk community, have driven the programming world into the realm of DDD.

What is Domain-Driven Design?

There are two layers in which it can be described:

  • strategic
  • tactical

Strategic DDD explains how to prepare and maintain a project. Its goal is to characterize parts of the system as Bounded Contexts, refine the terminology using Ubiquitous Language and illustrate the relationships using Context Maps. It is about gathering business expectations and needs. It shows how important it is to communicate doubts and questions back to the management. Finally, it is about IT working hand-in-hand with business to achieve a common goal.

Tactical DDD is a set of techniques used to construct a precise, coherent and useful model of the domain. It defines a set of building blocks such as Entities, Value Objects or Aggregates. It describes how to use Repositories and Factories to maintain the design and its implementation clean and well-defined.

Can DDD be used with Ruby on Rails?

Yes!

On the strategic level, you don't think about a framework or a programming language. Doman-Driven Design helps you to focus on the correct context. It teaches what kind of vocabulary to use and how to approach the architectural decisions.

On the tactical level, Domain-Driven shows that RoR doesn't have to be all about procedural services, quickly becoming god objects. It teaches how to describe your domain in a thought-out and flexible manner. It guides towards decoupled modules and consistent data.

How to start with DDD in Ruby on Rails

There is no one-way. I can only share mine. One thing you SHOULD NOT do at first is jumping right into The Blue Book. It may be too complicated without some initial preparation.

I've started by absorbing materials from various conferences and talks. I've been listening to DDD meetups and related podcasts. I've used recorded talks and high-level articles. When I felt ready, I ordered books by Evans and Vernon and started reading. What came to me as quite a shock was that I really got into them. I was so eager to know more that for the first time it didn't feel like reading "yet another programming book". It was like discovering a new world.

You have to find your own way. But believe me - it's worth it!

At first, it may be hard to incorporate DDD theory into such a conservative framework as Ruby on Rails. Luckily, you will find many examples in the upcoming blog posts within this series. You will also learn how to incorporate them into your projects.

Further Reading

Below, you can find a list of articles published in the DDD in Ruby on Rails series. Each encapsulates a portion of knowledge from tactical or strategic Domain-Driven Design. They are not ordered, but it may be easiest to read them in the listed sequence.

If you would like to first check if the topic is interesting to you, please check out the recording of or DDD webinars.

Domain-Driven Design Visuality Webinars

Resources

Articles in this series

Do you want to know more? Register for our DDD webinar

Paweł Strzałkowski
Chief Technology Officer

Check my Twitter

Check my Linkedin

Did you like it? 

Sign up To VIsuality newsletter

READ ALSO

Michal - Highlights from Ruby Unconf 2024

Highlights from Ruby Unconf 2024

14
.
11
.
2023
Michał Łęcicki
Conferences
Visuality
Cezary Kłos - Optimizing Cloud Infrastructure by $40 000 Annually

Optimizing Cloud Infrastructure by $40 000 Annually

14
.
11
.
2023
Cezary Kłos
Backend
Ruby on Rails

Smooth Concurrent Updates with Hotwire Stimulus

14
.
11
.
2023
Michał Łęcicki
Hotwire
Ruby on Rails
Software
Tutorial

Table partitioning in Rails, part 2 - Postgres Stories

14
.
11
.
2023
Jarosław Kowalewski
Backend
Postgresql
Ruby on Rails

N+1 in Ruby on Rails

14
.
11
.
2023
Katarzyna Melon-Markowska
Ruby on Rails
Ruby
Backend

Turbo Streams and current user

29
.
11
.
2023
Mateusz Bilski
Hotwire
Ruby on Rails
Backend
Frontend

Showing progress of background jobs with Turbo

14
.
11
.
2023
Michał Łęcicki
Ruby on Rails
Ruby
Hotwire
Frontend
Backend

Table partitioning in Rails, part 1 - Postgres Stories

14
.
11
.
2023
Jarosław Kowalewski
Postgresql
Backend
Ruby on Rails

Table partitioning types - Postgres Stories

14
.
11
.
2023
Jarosław Kowalewski
Postgresql
Backend

Indexing partitioned table - Postgres Stories

14
.
11
.
2023
Jarosław Kowalewski
Backend
Postgresql
SQL Views in Ruby on Rails

SQL views in Ruby on Rails

14
.
11
.
2023
Jan Grela
Backend
Ruby
Ruby on Rails
Postgresql
Design your bathroom in React

Design your bathroom in React

14
.
11
.
2023
Bartosz Bazański
Frontend
React
Lazy Attributes in Ruby - Krzysztof Wawer

Lazy attributes in Ruby

14
.
11
.
2023
Krzysztof Wawer
Ruby
Software

Exporting CSV files using COPY - Postgres Stories

14
.
11
.
2023
Jarosław Kowalewski
Postgresql
Ruby
Ruby on Rails
Michał Łęcicki - From Celluloid to Concurrent Ruby

From Celluloid to Concurrent Ruby: Practical Examples Of Multithreading Calls

14
.
11
.
2023
Michał Łęcicki
Backend
Ruby
Ruby on Rails
Software

Super Slide Me - Game Written in React

14
.
11
.
2023
Antoni Smoliński
Frontend
React
Jarek Kowalewski - ILIKE vs LIKE/LOWER - Postgres Stories

ILIKE vs LIKE/LOWER - Postgres Stories

14
.
11
.
2023
Jarosław Kowalewski
Ruby
Ruby on Rails
Postgresql

A look back at Friendly.rb 2023

14
.
11
.
2023
Cezary Kłos
Conferences
Ruby

Debugging Rails - Ruby Junior Chronicles

14
.
11
.
2023
Piotr Witek
Ruby on Rails
Backend
Tutorial

GraphQL in Ruby on Rails: How to Extend Connections

14
.
11
.
2023
Cezary Kłos
Ruby on Rails
GraphQL
Backend
Tutorial

Tetris on Rails

17
.
03
.
2024
Paweł Strzałkowski
Ruby on Rails
Backend
Frontend
Hotwire

EURUKO 2023 - here's what you've missed

14
.
11
.
2023
Michał Łęcicki
Ruby
Conferences

Easy introduction to Connection Pool in ruby

14
.
11
.
2023
Michał Łęcicki
Ruby on Rails
Backend
Ruby
Tutorial

When crazy ideas bring great time or how we organized our first Conference!

04
.
12
.
2023
Alexander Repnikov
Ruby on Rails
Conferences
Visuality