Welcome!

Microservices Expo Authors: Pat Romanski, Liz McMillan, Mamoon Yunus, Elizabeth White, Mehdi Daoudi

Blog Feed Post

Implementing Domain-Driven Design Book Review

Agile is not easy and implementing Domain-Driven Design (DDD) is not easy. I think my favorite part of the book is that the author realizes that, and also has a realistic perspective on what it takes to successfully use agile processes and DDD.

The book starts out with a really nice overview of DDD. By the time you are done the first chapter you have a pretty good high level picture of what DDD is all about. One topic he really drives home is Ubiquitous Language.

Ubiquitous Language is a shared team language that defines a certain domain. When you are reading about Ubiquitous Language it may seem like something that just happens on its own. It isn't. An explicit domain language should be defined, it should not just be allowed to implicitly come about. This same concept has been around for years in Water Fall, Unified Process, RUP, and other processes. It has always been a very important part of the software development process, so don't discount it.

Chapter 1 also does a great job of providing tips on how to show the business value of using DDD. The author has a clear understanding that without the support of the business you aren't going to get very far with your project, and in order to get them onboard you need to show them what they will gain by supporting DDD.

The remaining chapters dig into the details of DDD. I have listed the chapters below. Their titles are pretty self-explanatory.

Chapter 1. Getting Started with DDD
Chapter 2. Domains, Subdomains, and Bounded Contexts
Chapter 3. Context Maps
Chapter 4. Architecture
Chapter 5. Entities
Chapter 6. Value Objects
Chapter 7. Services
Chapter 8. Domain Events
Chapter 9. Modules
Chapter 10. Aggregates
Chapter 11. Factories
Chapter 12. Repositories
Chapter 13. Integrating Bounded Contexts
Chapter 14. Application
Appendix A. Aggregates and Event Sourcing: A+ES

I have seen a lot of teams that could not build software with UP or RUP adopt Scrum in hopes that changing the process will make a difference. It never does. There are a variety of reasons including not doing any architecture, not having experienced developers with the right skill sets, not having the right business users involved, not having the requirements elicitation skills needed, and the list can go on and on. The author clearly understands Scrum is not a silver bullet. I mention this because DDD done correctly can give agile processes a much better chance at success, but you must have the skills on the team in order pull it off.

I was really glad to see the author included a chapter on architecture. The author does a great job of covering a ton of architectural styles and patterns. Patterns, styles, and topic found in the Architecture chapter include Layers Architecture with the Dependency Inversion Principle, Hexagonal Architecture, SOA environment, REST, Data Fabric, Grid-Based Distributed Cache, and CQRS.

Every chapter is an in depth look at the topic of the given chapter. I did not leave any of the chapters feeling like I missed something. I have read both Domain-Driven Design: Tackling Complexity in the Heart of Software and Patterns of Enterprise Application Architecture, and I had both handy for looking up references to them. It is not necessary to read them first, but it did help that I had.

I am not going to say using DDD is easy, but I will say this book can definitely get you to where you can successfully use it. The author's writing style is really good and he is good at making the book entertaining. I will however say this, be prepared to read the entire book if you want to get to that point of successfully using DDD. There is a lot to learn, but it is worth it.

I highly recommend this book to every software architect and developer. Even if you don't go all out DDD there is a ton of great advice and wisdom found in this book that will help you improve your skills.

Implementing Domain-Driven Design

Read the original blog entry...

More Stories By Tad Anderson

Tad Anderson has been doing Software Architecture for 18 years and Enterprise Architecture for the past few.

@MicroservicesExpo Stories
In his session at 20th Cloud Expo, Scott Davis, CTO of Embotics, discussed how automation can provide the dynamic management required to cost-effectively deliver microservices and container solutions at scale. He also discussed how flexible automation is the key to effectively bridging and seamlessly coordinating both IT and developer needs for component orchestration across disparate clouds – an increasingly important requirement at today’s multi-cloud enterprise.
IT organizations are moving to the cloud in hopes to approve efficiency, increase agility and save money. Migrating workloads might seem like a simple task, but what many businesses don’t realize is that application migration criteria differs across organizations, making it difficult for architects to arrive at an accurate TCO number. In his session at 21st Cloud Expo, Joe Kinsella, CTO of CloudHealth Technologies, will offer a systematic approach to understanding the TCO of a cloud application...
API Security has finally entered our security zeitgeist. OWASP Top 10 2017 - RC1 recognized API Security as a first class citizen by adding it as number 10, or A-10 on its list of web application vulnerabilities. We believe this is just the start. The attack surface area offered by API is orders or magnitude larger than any other attack surface area. Consider the fact the APIs expose cloud services, internal databases, application and even legacy mainframes over the internet. What could go wrong...
The goal of Continuous Testing is to shift testing left to find defects earlier and release software faster. This can be achieved by integrating a set of open source functional and performance testing tools in the early stages of your software delivery lifecycle. There is one process that binds all application delivery stages together into one well-orchestrated machine: Continuous Testing. Continuous Testing is the conveyer belt between the Software Factory and production stages. Artifacts are m...
In IT, we sometimes coin terms for things before we know exactly what they are and how they’ll be used. The resulting terms may capture a common set of aspirations and goals – as “cloud” did broadly for on-demand, self-service, and flexible computing. But such a term can also lump together diverse and even competing practices, technologies, and priorities to the point where important distinctions are glossed over and lost.
In his session at @DevOpsSummit at 20th Cloud Expo, Kelly Looney, director of DevOps consulting for Skytap, showed how an incremental approach to introducing containers into complex, distributed applications results in modernization with less risk and more reward. He also shared the story of how Skytap used Docker to get out of the business of managing infrastructure, and into the business of delivering innovation and business value. Attendees learned how up-front planning allows for a clean sep...
Most companies are adopting or evaluating container technology - Docker in particular - to speed up application deployment, drive down cost, ease management and make application delivery more flexible overall. As with most new architectures, this dream takes a lot of work to become a reality. Even when you do get your application componentized enough and packaged properly, there are still challenges for DevOps teams to making the shift to continuous delivery and achieving that reduction in cost ...
Enterprise architects are increasingly adopting multi-cloud strategies as they seek to utilize existing data center assets, leverage the advantages of cloud computing and avoid cloud vendor lock-in. This requires a globally aware traffic management strategy that can monitor infrastructure health across data centers and end-user experience globally, while responding to control changes and system specification at the speed of today’s DevOps teams. In his session at 20th Cloud Expo, Josh Gray, Chie...
"At the keynote this morning we spoke about the value proposition of Nutanix, of having a DevOps culture and a mindset, and the business outcomes of achieving agility and scale, which everybody here is trying to accomplish," noted Mark Lavi, DevOps Solution Architect at Nutanix, in this SYS-CON.tv interview at @DevOpsSummit at 20th Cloud Expo, held June 6-8, 2017, at the Javits Center in New York City, NY.
We have already established the importance of APIs in today’s digital world (read about it here). With APIs playing such an important role in keeping us connected, it’s necessary to maintain the API’s performance as well as availability. There are multiple aspects to consider when monitoring APIs, from integration to performance issues, therefore a general monitoring strategy that only accounts for up-time is not ideal.
Web services have taken the development world by storm, especially in recent years as they've become more and more widely adopted. There are naturally many reasons for this, but first, let's understand what exactly a web service is. The World Wide Web Consortium (W3C) defines "web of services" as "message-based design frequently found on the Web and in enterprise software". Basically, a web service is a method of sending a message between two devices through a network. In practical terms, this ...
In his session at 20th Cloud Expo, Mike Johnston, an infrastructure engineer at Supergiant.io, discussed how to use Kubernetes to set up a SaaS infrastructure for your business. Mike Johnston is an infrastructure engineer at Supergiant.io with over 12 years of experience designing, deploying, and maintaining server and workstation infrastructure at all scales. He has experience with brick and mortar data centers as well as cloud providers like Digital Ocean, Amazon Web Services, and Rackspace. H...
All organizations that did not originate this moment have a pre-existing culture as well as legacy technology and processes that can be more or less amenable to DevOps implementation. That organizational culture is influenced by the personalities and management styles of Executive Management, the wider culture in which the organization is situated, and the personalities of key team members at all levels of the organization. This culture and entrenched interests usually throw a wrench in the work...
As many know, the first generation of Cloud Management Platform (CMP) solutions were designed for managing virtual infrastructure (IaaS) and traditional applications. But that’s no longer enough to satisfy evolving and complex business requirements. In his session at 21st Cloud Expo, Scott Davis, Embotics CTO, will explore how next-generation CMPs ensure organizations can manage cloud-native and microservice-based application architectures, while also facilitating agile DevOps methodology. He wi...
When you focus on a journey from up-close, you look at your own technical and cultural history and how you changed it for the benefit of the customer. This was our starting point: too many integration issues, 13 SWP days and very long cycles. It was evident that in this fast-paced industry we could no longer afford this reality. We needed something that would take us beyond reducing the development lifecycles, CI and Agile methodologies. We made a fundamental difference, even changed our culture...
We have Continuous Integration and we have Continuous Deployment, but what’s continuous across all of what we do is people. Even when tasks are automated, someone wrote the automation. So, Jayne Groll evangelizes about Continuous Everyone. Jayne is the CEO of the DevOps Institute and the author of Agile Service Management Guide. She talked about Continuous Everyone at the 2016 All Day DevOps conference. She describes it as "about people, culture, and collaboration mapped into your value streams....
These days, change is the only constant. In order to adapt and thrive in an ever-advancing and sometimes chaotic workforce, companies must leverage intelligent tools to streamline operations. While we're only at the dawn of machine intelligence, using a workflow manager will benefit your company in both the short and long term. Think: reduced errors, improved efficiency and more empowered employees-and that's just the start. Here are five other reasons workflow automation is leading a revolution...
Docker is sweeping across startups and enterprises alike, changing the way we build and ship applications. It's the most prominent and widely known software container platform, and it's particularly useful for eliminating common challenges when collaborating on code (like the "it works on my machine" phenomenon that most devs know all too well). With Docker, you can run and manage apps side-by-side - in isolated containers - resulting in better compute density. It's something that many developer...
While some vendors scramble to create and sell you a fancy solution for monitoring your spanking new Amazon Lambdas, hear how you can do it on the cheap using just built-in Java APIs yourself. By exploiting a little-known fact that Lambdas aren’t exactly single-threaded, you can effectively identify hot spots in your serverless code. In his session at @DevOpsSummit at 21st Cloud Expo, Dave Martin, Product owner at CA Technologies, will give a live demonstration and code walkthrough, showing how ...
Did you know that you can develop for mainframes in Java? Or that the testing and deployment can be automated across mobile to mainframe? In his session and demo at @DevOpsSummit at 21st Cloud Expo, Dana Boudreau, a Senior Director at CA Technologies, will discuss how increasingly teams are developing with agile methodologies, using modern development environments, and automating testing and deployments, mobile to mainframe.