When companies transform towards an agile and DevOps way of working, they sometimes ask how to proceed with architects. Some companies ignore architects in their transformation, some will upskill their architects, and some will make the DevOps teams responsible for the architecture. A core problem we see is that those Read more…
Ever since Nick Tune introduced the world to the Bounded Context Canvas, I incorporate it in my workshops and trainings. Nick sees the canvas as a checklist for designing our Bounded Context canvas. For me, it is also perfect as a visualisation tool to make the Bounded Context explicit. The one thing I am missing is examples in the form of acceptance criteria discovered and eventually formalised during our Behaviour Driven Development flow. In this post, I explain how I extended the Bounded Context Canvas with BDD examples from Example Mapping to show how to formalise the behaviour of a Bounded Context.
(more…)We live in a world of constant change. Today we generate more data than we can consume, and it contributes to the constant changes that we observe. Within the IT industry, we have the ambition to create flexible and reliable solutions that can cope with the demand for changes. We Read more…
Without a doubt, the bounded context pattern from Eric Evans book domain-driven design is one of the more essential patterns for designing and building modern software. Especially in the land of microservices architectures, where setting proper bounded context which is highly linked with the business goals aka the domain is essential to not get into the distributed monolith anti-pattern. The bounded context is in its core a language boundary, a boundary where language can stay consistent and which is the boundary of the model designed for a purpose. Boundaries for people are crucial from a culture perspective. People cannot live without boundaries; it is a way in which we can define our self and separate us from the rest. To define our self creates an identity, a feeling of belonging which in time can create ownership. However, to be able to define our self, we must also define the others to keep our own identity. When we look at cultural anthropology, we traditionally did this on the border through get-togethers like marketplaces, where we exchange goods. Now if we want to keep the cultural benefits of the bounded context within our company, we must also take care of the cultural needs designing bounded contexts. In this post, I describe these culture needs when using the bounded context pattern.
(more…)I’ve been involved in several transformations over the years, from DevOps to Digital to Agile. These transformations typically focus on transitioning people into near-autonomous teams of no more than eight people who will work in an agile manner. Every company I’ve worked for asks the same questions at these transformations: Read more…
Over recent years, a tool called EventStorming became one of the go-to techniques for Domain-Driven Design consultants to collaboratively explore complex business domains at customers. Since consultants travel a lot from company to company helping with their questions about approaching software delivery this poses a small 1st world problem; How can we still comfortably travel while still carrying the required equipment to do an EventStorming at the customer (without breaking our back or needing a personal fitness coach). This was exactly the conversation we, Maxime Sanglan-Charlier and Kenny Baas-Schwegler, had during DDD Europe 2019. In this post, Maxime and Kenny will share their quest in finding the perfect EventStorming backpack.
(more…)with EventStorming and Example Mapping
This article was published in the leanpub book: Domain-Driven Design: The First 15 Years
People often ask for more concrete guidance on how to explore models, especially in an Agile or Lean setting. The model exploration whirlpool is Eric Evans attempt to capture such advice in writing. It is not a development process, but a process that fits in most development processes. The central theme revolving the process is to keep challenging the model. While the process itself for most is straightforward and easy to understand, there are not many concrete examples to find on how to do such a model exploration whirlpool. Most people when starting to use Domain-driven design (DDD) are looking for these practical examples. In this article, I will tell you my story of how I used the model exploration whirlpool by combining EventStorming, a technique that came from the DDD community, and Example Mapping, a technique from Behaviour Driven Development (BDD) community.
(more…)We see a lot of companies are moving towards a microservice architecture. The big pitfall of microservices architecture is to focus on the technology, how big the microservice needs to be, how many lines of codes, what entities do we put in a microservice, and using rest as the communication between them. But to succeed we need to focus on the problem space, by crunching domain knowledge and do domain modelling. EventStorming is a perfect fit for domain modelling, and almost all the microservices leaders seem to agree. Even ThoughtWorks finally put EventStorming on ‘adopt’ in their most recent rendition of their technology radar. But EventStorming has grown to be more than just a tool for domain modelling and to be successful and create autonomous teams you need to use EventStorming for more than only domain modelling.
We design, model, and create software to solve a problem for our customer (this can also be a customer from within the same company). Only when we do so, we focus naturally on solving the happy path and want to deliver that value as soon as possible. The only problem here is that we will always come to a point where we get corner cases or business exceptions, and the question starts to arise, what shall we do? Is it worth the effort to invest in building a solution for this, or can we leave this function out of the system because it is not worth it? To answer this question, we want, if possible, feedback from the system to know this. We can quickly get this feedback making it explicit in the form of a Domain Event during our EventStorming and start monitoring it. This way we can leave the options open until we know what to do.
Technical design decision can have a severe impact on companies their communication structure. Conway’s law explains; “Any organization that designs a system (defined more broadly here than just information systems) will inevitably produce a design whose structure is a copy of the organization’s communication structure.” Such is the story also with a microservices architecture. A lot of companies decide to use REST to communicate between bounded contexts and or services. What can happens is that the services in the bounded context now get dependent on each other. The dependency on finishing a service their process will resolve in cascading failures if a service is down. Cascading failures will reflect on the way organizations communicate between teams. Teams now rely on each other before finishing their process. Dependency between teams can severely disrupt the company to respond better to the fast-changing demands of customers; companies get more entangled than before. To combat getting cascading failures, we must follow the communication structure of the business. We can do this by using Event Storming and going events-first.