EventStorming

EventStorming is a family of Collaborative Modelling workshop formats that allows you to explore complex domains effectively and engagingly

It’s also one of our house specialities. Proudly invented here.

A bit of history

EventStorming was born more or less by chance around 2013 to draft complex software business processes in an Event-Driven way.

The initial name, “Event-based modelling”, was dropped during Vaughn Vernon’s IDDD Tour (found some notes from Jef Claes and Tom Janssens), where Alberto Brandolini featured as a guest trainer. The term “Event-based” was already used in Vaughn’s material, so a last-minute name change happened just before going on stage in Leuwen, and EventStorming was born.

(Yep, the official spelling is a single word: EventStorming, not Event Storming).

Given the audience’s enthusiastic response to the experiment, Alberto wrote the first blog post about the format.

That was the beginning of a rollercoaster. A small community of practitioners was born, and experiments and variations flourished. This led to many conference talks, starting to write a book, and using EventStorming in many different business domains worldwide.

Though the original idea was born with a Domain-Driven Design mindset, the collaborative storytelling format based on orange events proved very versatile, supporting discovery and design-oriented workshops.

Key principles

The most effective conversations happen when modelling tools support people. However, traditional modelling tools like flipcharts and whiteboards constrain the space available and the number of items to discuss. A standard recommendation is to avoid drawing more than seven items on a diagram. But this approach only works if your problem is small enough to fit in.

How do we solve big, rotten problems? How do we handle issues that result from dozens of interconnected factors?

As David Sibbet put it in his book Visual Meetings:

“Can’t do system thinking without visualisation.”

Big problems need visualisation even more than small ones; we need different tools for that.

Digital modelling tools replace space constraints with new ones, adding barriers (complex notations, familiarity, license costs, etc.) to parallel contributions and ultimately reducing the space for effective collaboration.

EventStorming breaks the space limitation while staying in the physical space. The paper roll provides the illusion of an unlimited modelling surface, and the lo-fi notation based on coloured sticky notes lowers the barrier to active contribution.

Put another way: you don’t need to lose detail if you have enough space. You can see the forest and the trees just walking around the room.

Massive parallel contributions can quickly turn into a mess. The different formats have different facilitation strategies to keep the workshop in “the zone”.

Main recipes

The original proposition from Alberto Brandolini’s blog was about a single format, but over the years, three main flavours emerged:

• Big Picture EventStorming is a large-scale workshop aiming to discover the intricacies of an entire business line. It usually involves 20 to 30 people, but this largely depends on the complexity of the organisation’s domain.
• Process Modelling EventStorming is oriented to an end-to-end specific process (including its variations). It can be used for discovery and/or design and usually involves fewer participants than a Big Picture session.
• Software Design EventStorming has a similar scope. The original format was initially targeted at discovering aggregates in Domain-Driven Design, then progressively became a more sophisticated modelling tool, allowing the detection of boundaries and the design of robust, loosely coupled systems.

You can use the different formats individually–Big Picture is great for large-scale retrospectives, for example–or chain them. For instance, we can use Big Picture EventStorming to detect the most relevant area for improvement and then drill into it with Process Modelling EventStorming.

Sometimes, a more detailed format – like Software Design EventStorming blends in, introducing technical discussion without displacing the business-driven conversation.

Let’s explore the formats with a little more detail.

---

Big Picture EventStorming

This format leverages the unlimited modelling surface idea to avoid the trap of unnecessary scope limitations. We need a system-level view and enough space to address systemic issues.

Most workshops focus on a specific business line, but it’s not uncommon to explore scenarios where multiple business lines share (or compete for) some resources or processes.

Depending on the organisation’s size, a different number of people would be involved. Typical numbers vary between 15 and 30.

Standard Steps

• Invite the right people. Experts and explorers. People with questions and people with answers. The more perspectives, the more insights.
• Provide an Unlimited Modelling Surface or the closest approximation. A plotter paper roll on a 10-12 metres straight surface is usually enough to describe most business lines end-to-end. But make sure to have an abundant supply of markers and sticky notes.
• An initial round of chaotic exploration, where participants will contribute to the global narrative with the Events they know, should lay the foundation for the next steps. Now we have a mess to sort out.
• Enforcing the timeline is the first round of sorting. This is where the first relevant conversations usually happen, and a more robust structure emerges. We’ll capture emergent frictions with magenta Hot Spots and start placing some boundaries on our surface.
• People and Systems would be the next ingredient to our growing narrative and usually a source for more Hot Spots.
• Now, we should have enough information for an explicit walkthrough. A narrator will try to tell a precise story to a picky audience, while a scribe will ensure the model is updated with the necessary corrections.

At the end of the walkthrough, we should have a validated narrative: what is visible has been presented, corrected, refined and approved. Great! Now everybody is on the same wide-scale page.

Custom Steps

The validated narrative is a versatile artefact that could be the perfect background for more interesting steps. You may pick the ones which are more suitable for your scenario:

• Playing with value allows visualising and discussing steps and activities that deliver or destroy value for your customers, employees, stakeholders, etc.
• Problems and opportunities explores explicit issues with the current model and allows proposing solutions to open issues or new ideas to tackle opportunities.
• Arrow Voting can quickly visualise the convergence on a specific issue, which is probably your organisation’s current main blocker.
• Extracting User Stories is a common step when using Big Picture EventStorming in a software development project kick-off scenario.
• Extracting Bounded Contexts is the perfect homework for your technical team to derive a Context Map from your EventStorming exploration.
• Visualise ownership may make the connection between your flow and your development teams’ areas of responsibility evident.

And the list can grow. A validated narrative is a great background for many discussion types.

Typical scenarios

Big Picture EventStorming is by far the most versatile recipe. You can choose a combination of custom steps to suit your needs better, designing the most fitting experience. However, the workshop is a tool to serve your business needs. Here are some common scenarios.

• It can be a key step in an Architecture Modernisation initiative to highlight the current tensions in your architectural landscape.
• You may use the Big Picture format to run a large-scale corporate retrospective focused on collaboration between different departments. This usually occurs at pivotal moments in your company’s growth, like transitioning to scale-up, after a big merger, etc.
• It can initiate software projects, explore the hypothetical project scope and surrounding areas, and dramatically speed up the requirements-gathering phase.
• It could be used to envision new businesses focusing on the future by leveraging the “wisdom of the room” and building a robust future hypothesis narrative.

The list may continue. Variations of the format can be used to build sensible roadmaps and plans, structured storyboarding, and more.

The outcome

It’s easy to mistake the artefact for the actual workshop outcome. It’s big and colourful and provides a reference shape for your business.

This is great, but the conversations needed to build the shared model are usually the most valuable outcome of the workshop. They dig into years and misunderstandings and across silo boundaries to provide clarity and confidence to key people in your organisation.

When you can finally observe your system as a cohesive whole, you enable change. People are afraid of breaking invisible things, and our relentless effort to make everything visible turns even the more intricate businesses into something that can be improved.

Why is it relevant?

The larger the organisation, the harder it becomes to detect and solve problems, especially those that don’t have clear ownership. When teams are overburdened, they focus on their local scope, waiting for someone to address the systemic issues.

Acting on areas with unclear ownership requires clarity, coordination and political consensus, and Big Picture EventStorming provides exactly that.

It investigates the whole system but separates the key signal from the noise. It provides a detailed background for deeper analysis and issue resolution. Then, it leverages the presence of the key decision-makers in the room to provide the political support and momentum needed to address and solve the most important issues.

Last but not least, it can be the perfect companion to strategic tools like Wardley Maps or Impact Mapping, ensuring the vision is aligned with the current reality.

---

Process Modelling EventStorming

The Process Modelling format is a great tool for discovering the intricacies of complex business processes and designing new ones. It builds on the idea of collaborative games, providing your modelling team with a simple set of rules.

1. 1. Every path should be completed.
   2. The grammar must be respected.
   3. Every stakeholder should be reasonably happy.
   4. Every Hot Spot should be addressed.

Rule number one is the most straightforward: a process ends in a stable state, usually an Event that requires no further action.

The more peculiar rule is respecting grammar. It’s been designed to force workshop participants to address tough questions, and they need a couple of interactions to become confident.

Rule number 3 opens the door to business value and UX concerns, allowing your modelling team to balance mechanical steps for formal flow correctness with emotional ingredients like “how a given message impacts the user’s feelings.”

Finally, Hot Spots will allow you to visualise critical areas, suggesting that your design won’t be perfect from the beginning. Instead, it will be incrementally refined, addressing the emerging concerns one by one.

The result is a very enjoyable Collaborative Modelling experience, where different perspectives can blend into a design that addresses interdisciplinary concerns without falling into the trap of design by committee.

The outcome

The resulting artefact of a Process Modelling EventStorming is a lo-fi battle-tested process description that can get progressively enhanced with trickier corner cases.

Once again, the journey matters. Every Hot Spot addressed during the discussion is the equivalent of a new revision of a more formally specified process.

Shared ownership and the consequential buy-in are interesting consequences of the Collaborative Modelling approach. Concerns are explicit from the beginning, and addressing them together gives more optionality in resolution.

Why is it relevant?

Complex business processes are rarely designed collaboratively, but modern processes—especially the customer-facing ones—are a mix of formal robustness and user experience concerns.

One-sided design processes may require a long negotiation before approval, but they can’t avoid last-minute surprises. A collaboratively designed process may address blocking concerns from the inception phase, leading to a solution with embedded buy-in.

Process Modelling EventStorming is the ideal format for supporting a discussion that merges the different perspectives into a powerful codesigned artefact.

---

Software Design EventStorming

The Software Design EventStorming aims to design software models to support complex business processes. The Event-driven nature of the exploration makes it a perfect modelling tool for Domain-Driven Design, keeping the discussion in the liminal space between business and technology but supporting more software-oriented activities like determining boundaries between cooperating models (see also Context Mapping) and enforcing consistency on the Aggregates lifecycle.

Software Design EventStorming is still based on the idea of collaborative games but expands the grammar with extra building blocks and extends the Process Modelling ruleset with two extra rules.

1. 5. Boundaries should be visualised.
   6. Software components should have consistent behaviour.

The expanded grammar allows boundaries to be visualised—and moved, in the case of discussions—bringing coherence to the picture.

 

Boundaries will move the discussion into the competing purposes of the stakeholders involved, providing a fantastic playground for Greenfield Context Mapping. Meanwhile, we can detect signals to define a semantically robust lifecycle for our emerging Aggregates.

We can include wireframe sketches in the discussion, especially if the page layout actively influences your users’ decisions.

A Software Design EventStorming session is also a great place to stress and distil your Ubiquitous Language or to stress your model with complex real-world scenarios that can be turned into acceptance tests.

The outcome

A Software Design EventStorming usually results in a left-to-right flow where boundaries and key building blocks start to emerge. Aggregates are shaped by their behaviour and role in the end-to-end interaction, looking more like state machines than data containers.

Green Read Models instead capture the data needed to make key decisions. The discussion also raises many issues we can capture with magenta Hot Spots.

Another significant outcome is probably in the trashcan: ideas we tried and discarded, wordings that turned out naive after closer scrutiny, and Hot Spots we resolved in a previous iteration.

The model starts wrong and progressively evolves towards greatness, with everybody’s contribution progressively rewriting and rearranging the building blocks.

Why is it relevant?

Complex business processes are often a source of coupling inside enterprise software applications. Traditional strategies for requirements gathering too often fail to resolve inconsistencies when multiple stakeholders are involved.

Software Design EventStorming enforces coherence between the business and technical perspectives, leveraging domain events to build more precise narratives and effective implementation.

Events are a semantically more robust building block for describing the behaviour of complicated systems and enabling architectural opportunities such as Event-Driven Architecture or CQRS/ES.

Putting it all together

As a whole, EventStorming is an incredibly versatile tool. We can use it to investigate an intricate current state or envision a possible future.

We can embrace the unlimited modelling space metaphor and explore the system as a whole or focus on a specific business flow.

EventStorming can support strategic business decisions and help you design better services and more effective and efficient software applications.

More than anything, it can improve collaboration between people from different backgrounds, turning design discussions into enjoyable experiences.

---

EventStorming is a key ingredient of Avanscoperta’s consulting services.

We also offer learning experiences such as the EventStorming Masterclass, or the EventStorming Remote Experience.

You may want to check the EventStorming Resources page on our partner website EventStorming.com.