Alberto Brandolini has been evangelizing the idea of EventStorming?for a while now. It is a powerful workshop format to breakdown complex business problems pertaining to real world scenarios. The idea took its shape from the Event Sourcing implementation style laid out by Domain Driven Design. The outcome of the workshop format produces a model perfectly aligned with the idea of DDD and lets you identify aggregate and context boundaries fairly quickly. The approach also leverages easy-to-use notations and doesn’t require UML, that in itself, might become a deterrent for some participants of a workshop who are not so familiar with UML notations.
The core idea of EventStorming is to make the workshop more engaging and evoke thought provoking responses from the participants. A lot of times discovery is superficial and figuring out the details are deferred for later. On the contrary, EventStorming allows participants to ask some very deep questions about the business problem that were very likely playing in their sub-conscious minds. It creates an atmosphere where the right questions can arise.
A core theme of this approach is unlimited modeling space. Modeling complex business problems is often constrained by space limitations (mostly whiteboard), but the approach allows anything to be leveraged as a platform where the problem can be modeled. You may pick anything that can come in handy and help you get rid of the space limitations.
Another core theme of this approach is the focus on Domain Events. Domain Events represent meaningful actions in the domain with suitable predecessors and successors. Placing events in a timeline on a surface allows people to visualize upstream and downstream activities and model the flow easily in their minds. Domain events are further annotated with user actions that are represented as Commands. You can also color code the representation to distinguish between user actions and system commands.
The next aspect to investigate is Aggregates. Aggregates here should represent a section of the system that receives the commands and decides on their execution. Aggregates produce Domain Events.
While a Domain Event is key to this exploration technique, along the way you are also encouraged and motivated to explore Subdomains, Bounded Context and User Personas. Subsequently, you also look at Acceptance Tests to remove any amount of ambiguity arising out of edge-case scenarios.
