Free DDD Learning Resources: A Curated List of Blog Posts, Videos, Ebooks, and More on Domain Driven Design
Domain Driven Design Download Ebook: A Guide for Developers
If you are a developer who wants to learn how to design and build software that is aligned with the business needs and domain knowledge, you might be interested in domain driven design (DDD). DDD is an approach to software development that focuses on the core domain and domain logic, rather than on technical details or frameworks. DDD helps you to create software that is flexible, maintainable, testable, and scalable.
domain driven design download ebook
In this article, we will explain what domain driven design is, what are its benefits and challenges, how to implement it using various patterns and practices, and where to download ebooks on domain driven design. By the end of this article, you will have a better understanding of DDD and how it can help you to create better software.
What is Domain Driven Design?
Domain driven design is a way of thinking and a set of principles for software development that was popularized by Eric Evans in his book Domain-Driven Design: Tackling Complexity in the Heart of Software. The main idea behind DDD is that the software should be based on the domain model, which is a representation of the business concepts, rules, and behaviors that are relevant to the problem domain.
The domain model is not a static or fixed entity, but rather an evolving and collaborative artifact that is refined and validated through continuous interaction with domain experts, who are the people who have deep knowledge and experience in the problem domain. The domain model should capture the essence and the complexity of the domain, while avoiding unnecessary details or technicalities.
The domain model should also be expressed in a ubiquitous language, which is a common and consistent vocabulary that is shared by developers and domain experts. The ubiquitous language should be used in all forms of communication, such as code, documentation, diagrams, tests, etc. The ubiquitous language helps to bridge the gap between the technical and the business worlds, and to ensure that the software reflects the reality of the domain.
The benefits of Domain Driven Design
Some of the benefits of applying domain driven design are:
It improves the quality and readability of the code, as it follows the natural structure and logic of the domain.
It facilitates communication and collaboration among developers and domain experts, as they use a common and consistent language.
It reduces ambiguity and misunderstanding, as the code and the domain model are aligned and synchronized.
It enables faster feedback and validation, as the code and the domain model are tested and verified against the domain knowledge and expectations.
It supports change and evolution, as the code and the domain model are modular and adaptable to new requirements or insights.
It enhances scalability and performance, as the code and the domain model are optimized for the specific needs and characteristics of the domain.
The challenges of Domain Driven Design
Some of the challenges of applying domain driven design are:
It requires a lot of time and effort to discover, analyze, and model the domain, as it involves a lot of research, interviews, workshops, prototyping, etc.
It requires a high level of skill and expertise from developers, as they need to master the domain knowledge, the DDD principles and patterns, and the technical tools and frameworks.
It requires a close and continuous collaboration between developers and domain experts, as they need to share feedback, validate assumptions, resolve conflicts, etc.
It requires a clear and consistent vision and strategy for the software development process, as it involves a lot of decisions, trade-offs, priorities, etc.
It requires a culture and mindset shift for both developers and domain experts, as they need to embrace complexity, uncertainty, change, etc.
How to implement Domain Driven Design?
There is no one-size-fits-all or prescriptive way to implement domain driven design. However, there are some common patterns and practices that can help you to apply DDD in your software development projects. These patterns and practices can be divided into three categories: building blocks, strategic patterns, and tactical patterns.
The building blocks of Domain Driven Design
The building blocks of DDD are the basic elements that you can use to create your domain model. They include:
Entities
An entity is an object that has a unique identity and a lifecycle. It is defined by its identity rather than by its attributes or behavior. For example, a customer or an order are entities. Entities usually have relationships with other entities or value objects.
Value Objects
A value object is an object that has no identity and is immutable. It is defined by its attributes or behavior rather than by its identity. For example, a color or a date are value objects. Value objects usually represent concepts or measurements that are relevant to the domain.
Aggregates
An aggregate is a cluster of entities and value objects that are treated as a single unit. It has a root entity that acts as the gateway to access or modify the aggregate. It also has boundaries that define its consistency and integrity rules. For example, an order and its order lines can form an aggregate. Aggregates help to simplify the domain model and to enforce business rules.
Repositories
A repository is an object that provides access to aggregates or entities. It abstracts away the details of how the aggregates or entities are stored or retrieved from the data source. It also provides methods to query or manipulate the aggregates or entities. For example, an order repository can provide methods to find orders by customer or status.
Services
A service is an object that performs an operation that does not belong to any entity or value object. It usually encapsulates some domain logic or functionality that is not related to any specific aggregate or entity. For example, a notification service can send emails or messages to customers or users.
Factories
A factory is an object that creates aggregates or entities. It hides the complexity of how the aggregates or entities are instantiated or initialized. It also ensures that the aggregates or entities are created in a valid state. For example, an order factory can create orders with default values or parameters.
Modules
A module is a group of related building blocks that form a cohesive unit. It helps to organize the domain model into logical and manageable chunks. It also helps to avoid coupling and dependency among different parts of the domain model. For example, a sales module can contain all the building blocks related to sales operations.
The strategic patterns of Domain Driven Design
The strategic patterns of DDD are the high-level concepts that help you to define the scope and boundaries of your domain model. They include:
Bounded Contexts
Ubiquitous Language
A ubiquitous language is a common and consistent vocabulary that is used within a bounded context. It reflects the domain concepts, rules, and behaviors that are relevant to the bounded context. It also helps to communicate and collaborate effectively among developers and domain experts within the bounded context. For example, a sales ubiquitous language can include terms such as order, customer, product, discount, etc.
Context Mapping
A context mapping is a diagram that shows the relationships and interactions among different bounded contexts. It helps to identify the dependencies, conflicts, gaps, overlaps, etc. among the bounded contexts. It also helps to define the integration strategies and patterns among the bounded contexts. For example, a sales bounded context can have a customer/supplier relationship with an inventory bounded context, which means that the sales bounded context depends on the inventory bounded context for providing product information.
Subdomains
A subdomain is a subset of the domain that has its own specific focus and complexity. It helps to prioritize and categorize the different aspects of the domain. It also helps to decide which subdomains are core, supporting, or generic. A core subdomain is the most important and valuable part of the domain that provides competitive advantage or differentiation. A supporting subdomain is a necessary but not critical part of the domain that supports the core subdomain. A generic subdomain is a common and standard part of the domain that can be outsourced or reused. For example, a sales subdomain can be a core subdomain for an e-commerce domain, a supporting subdomain for a banking domain, or a generic subdomain for a health care domain.
The tactical patterns of Domain Driven Design
The tactical patterns of DDD are the low-level concepts that help you to implement your domain model. They include:
Specification
A specification is an object that encapsulates a business rule or condition that can be verified or applied to other objects. It helps to decouple and reuse the business logic from the entities or value objects. It also helps to compose complex rules or conditions from simple ones. For example, a discount specification can check if an order meets certain criteria to apply a discount.
Domain Events
A domain event is an object that represents something meaningful or significant that happened in the domain. It helps to capture and communicate the changes or actions that occur in the domain. It also helps to trigger or coordinate other behaviors or reactions in response to the event. For example, an order placed event can notify other bounded contexts or services that an order has been placed.
Event Sourcing
Event sourcing is an approach to persisting and retrieving data that uses domain events as the source of truth. It helps to store and replay the history of changes or actions that occurred in the domain. It also helps to support auditing, debugging, testing, analytics, etc. For example, an order aggregate can be reconstructed from a sequence of order events.
CQRS
CQRS stands for Command Query Responsibility Segregation. It is an approach to designing and implementing systems that separates the write operations (commands) from the read operations (queries). It helps to optimize and scale each operation independently according to its needs and characteristics. It also helps to support different models or views for each operation. For example, an order command model can handle creating or updating orders, while an order query model can handle retrieving or searching orders.
Where to download ebooks on Domain Driven Design?
If you want to learn more about domain driven design and how to apply it in your software development projects, you might want to download some ebooks on DDD. Here are some of the best ebooks on DDD that you can find online.
The best ebooks on Domain Driven Design
These are some of the most popular and influential ebooks on DDD that cover the theory and practice of DDD in depth.
Domain-Driven Design: Tackling Complexity in the Heart of Software by Eric Evans
This is the original and classic book on DDD that introduced and explained the core concepts and principles of DDD. It is considered as the bible of DDD by many developers and domain experts. It covers topics such as ubiquitous language, bounded contexts, entities, value objects, aggregates, services, repositories, factories, modules, specifications, domain events, etc. It also provides examples and case studies from various domains and industries. You can download this ebook from Amazon Kindle Store.
Implementing Domain-Driven Design by Vaughn Vernon
This is a practical and comprehensive guide on how to implement DDD using various patterns and practices. It covers topics such as context mapping, bounded contexts, ubiquitous language, subdomains, aggregates, repositories, domain events, event sourcing, CQRS, etc. It also provides examples and case studies from various domains and industries. You can download this ebook from Amazon Kindle Store.
Patterns, Principles, and Practices of Domain-Driven Design by Scott Millett and Nick Tune
This is a modern and updated book on DDD that covers the latest trends and developments in DDD. It covers topics such as strategic design, tactical design, microservices, bounded contexts, ubiquitous language, subdomains, aggregates, repositories, domain events, event sourcing, CQRS, etc. It also provides examples and case studies from various domains and industries. You can download this ebook from Amazon Kindle Store.
The best websites to download ebooks on Domain Driven Design
These are some of the best websites that offer ebooks on DDD for free or for a low price.
Amazon Kindle Store
This is the largest and most popular online store for ebooks. You can find thousands of ebooks on DDD and related topics. You can also read reviews and ratings from other readers. You can download the ebooks to your Kindle device or app, or read them online using the Kindle Cloud Reader. You can also get some ebooks for free or for a discounted price using the Kindle Unlimited or Prime Reading programs.
Google Play Books
This is another large and popular online store for ebooks. You can find hundreds of ebooks on DDD and related topics. You can also read reviews and ratings from other readers. You can download the ebooks to your Android device or app, or read them online using the Google Play Books web reader. You can also get some ebooks for free or for a discounted price using the Google Play Books deals or promotions.
Leanpub
This is a unique and innovative online platform for authors and readers of ebooks. You can find dozens of ebooks on DDD and related topics. You can also interact with the authors and provide feedback or suggestions. You can download the ebooks in various formats such as PDF, EPUB, MOBI, etc. You can also pay what you want for the ebooks or get them for free.
Conclusion
Domain driven design is an approach to software development that focuses on the core domain and domain logic, rather than on technical details or frameworks. DDD helps you to create software that is flexible, maintainable, testable, and scalable.
In this article, we have explained what domain driven design is, what are its benefits and challenges, how to implement it using various patterns and practices, and where to download ebooks on domain driven design.
We hope that this article has helped you to learn more about DDD and how it can help you to create better software.
FAQs
Here are some frequently asked questions about domain driven design.
What is the difference between domain driven design and object oriented design?
Object oriented design (OOD) is a paradigm of software development that uses objects as the basic units of abstraction and encapsulation. OOD focuses on the structure and behavior of objects, rather than on the data or functions.
Domain driven design (DDD) is an approach to software development that uses domain models as the basis of abstraction and encapsulation. DDD focuses on the concepts and rules of the domain, rather than on the technical details or frameworks.
OOD and DDD are not mutually exclusive or contradictory. They can be used together to create software that is both object oriented and domain driven.
What are some examples of domains?
A domain is a sphere of knowledge or activity that defines a problem space or an opportunity space for software development. A domain can be anything that has its own concepts, rules, behaviors, etc.
of domains are:
E-commerce: The domain of online shopping and selling.
Banking: The domain of financial transactions and services.
Health care: The domain of medical diagnosis and treatment.
Social media: The domain of online communication and interaction.
Gaming: The domain of entertainment and simulation.
What are some tools or frameworks that support domain driven design?
There are many tools or frameworks that can help you to implement domain driven design in your software development projects. Some of them are:
Spring Boot: A Java-based framework that simplifies the creation of web applications and microservices. It supports DDD concepts such as aggregates, repositories, services, domain events, etc.
Laravel: A PHP-based framework that provides a web application development environment and a rich set of features. It supports DDD concepts such as entities, value objects, services, repositories, etc.
Django: A Python-based framework that offers a high-level and rapid web development platform. It supports DDD concepts such as models, views, forms, etc.
Rails: A Ruby-based framework that enables the development of web applications and APIs. It supports DDD concepts such as active record, controllers, views, etc.
Akka: A Scala-based toolkit that enables the creation of concurrent and distributed systems. It supports DDD concepts such as actors, messages, events, etc.
What are some resources or references to learn more about domain driven design?
There are many resources or references that can help you to learn more about domain driven design. Some of them are:
Domain Language: The official website of Eric Evans and his company. It provides information, articles, videos, courses, etc. on DDD.
DDD Community: The online community of DDD practitioners and enthusiasts. It provides forums, blogs, events, podcasts, etc. on DDD.
InfoQ Domain Driven Design: The section of InfoQ website that covers DDD topics. It provides news, articles, videos, presentations, etc. on DDD.
Martin Fowler Domain Driven Design: The section of Martin Fowler website that covers DDD topics. It provides articles, videos, books, etc. on DDD.
Fun Fun Function Domain Driven Design: A YouTube playlist by Mattias Petter Johansson that explains DDD concepts and examples in a fun and easy way.
How to test domain driven design?
Testing domain driven design is an important part of the software development process. It helps to ensure that the software meets the business needs and expectations. There are different types of testing that can be applied to DDD:
Unit testing: Testing the individual building blocks of the domain model, such as entities, value objects, aggregates, services, repositories, factories, etc.
Integration testing: Testing the interactions and integrations among different building