With this article, I would like to introduce you to EventStorming and explain to you how to get started. I am not discovering anything new, just gathering available knowledge in one place. What I will show you is a few tips on how to conduct and facilitate EventStorming workshops.
Guide to Big Picture EventStorming
In 2013 Alberto Brandolini posted an article about a new workshop format for quick exploration of complex business domains. It was warmly welcomed by the DDD community. In 2015 Technology Radar described EventStorming as worthy of attention and three years later as a recommended method for business domain modelling in information systems.
During the years a lot has changed, the technique has developed and matured but the main idea remained the same:
EventStorming is a flexible workshop format that allows a massive collaborative exploration of complex domains (…) where software and business practitioners are building together a behavioural model of the whole business line.
The above definition is from Alberto Brandolini’s Introducing EventStorming, to which I will be referring in this article.
Provide unlimited modelling space
Why is it important? Because you want participants to explore and experiment during the workshop. You don’t want to impose limits on them or to allow a situation where someone doesn’t add an event because there is no space left.
For stationary session you need:
- wall where you attach plotter paper (it is easier to stick post-its on plotter paper),
- stickies in different colours, shapes and quantity (will discuss it later),
When it has to be online, you can use a virtual boards such as:
There are two approaches to facilitate and that depends on general participants’ understanding of the business process.
If your team does not know the domain it is good to conduct a workshop in an exploratory way, because there are a lot of unknowns. You can start with adding a central event, or if the domain is large - several events. Then look at what is happening before and after those events regarding time flow.
However, if your participants are familiar with the system (domain) and the goal is to discover only a part of it, see how something works or immerse into a specific use-case. You may want to impose certain boundaries - e.g. by initial and final events.
Depending on what you want to achieve and how deep you want to explore your business, we can distinguish three possible formats:
- Big Picture EventStorming - when you want to look at your business from above (a helicopter view),
- Process Level EventStorming - going deeper with details but you still focus on whole view,
- Design Level EventStorming - you break down your current process into smaller areas and then model them step by step using DDD, CQRS and/or Event Sourcing.
In his book Alberto Brandolini is mentioning also other formats, however, I would like to narrow the scope for the most important ones. In this article I focus on the Big Picture approach as it is the first and crucial step to start exploring our business.
I focus here on the main building blocks without going into details. A comprehensive description can be found in the book mentioned earlier.
Invite the right people - business, UX, IT
but how do you describe the right people?
- those who have questions
- developers, architects, designers etc.
- and those who know the answers
- you will need people that care about the problem
- people who know the business. Try to gather people who know and understand it. Don’t confuse them with users — people who are using our business/system (I mean these two words interchangeably and will use business across the article) — these two are totally opposite.
Orange sticky note
On which we will write down our events in the following form:
- Verb in past tense to indicate that it already happened
Relevant for domain experts - describing specific and pertinent events or changes in our business - these are changes that at the end of the day we want to save in the database.
Tip: It is a good practice to define the concept of an event together (with participants) at the beginning of the workshop. Then we can verify our definition with events that are appearing on the wall.
- we have verbs in past tense,
- they are all relevant changes in our blog business,
Phases of Big Picture EventStorming workshop
It is good to start the workshop with a short introduction of all participants - but it has to be rather quick before everybody gets bored. Generally you can omit this step and ask only new participants to introduce themselves.
We are going to explore the business process as a whole by placing all the relevant events along a timeline. We will highlight ideas, risks and opportunities along the way.
What is necessary - we need to set a goal. What will we model? Say “What is our goal? What we will model?” and try to analyse.
Tip: Remember - EventStorming is not a goal by itself - it is only a tool / framework.
Because the Big Picture is all about events
Provide participants with an idea of a domain event, why it is important and that it has to be a relevant change in our system. Imagine you do not have a computer and by the end of the day every event in our system needs to be written down in a notebook, by hand. Is the event ‘offer was shown’ a relevant change you want or is it worth noting?
Tip: A good ice-breaker is also demonstrating how to peel the sticky note so it would not curl up… for example here.
Phase 1 Chaotic exploration (brain dump)
What is happening
All participants are using orange sticky notes, writing down events and putting them on the board. When events start appearing on the board, a discussion will naturally start about what kind of events they are, when they are happening or how or what is triggering them.
Your role as a facilitator
Explain that we treat our whole board as a timeline and time is passing from left to right - it helps to see what is happening before and after. Sometimes it is worth showing the importance of time in an example:
- a locker was opened,
- a package was taken out,
- the door was closed.
In a different order it does not make sense.
Your role as a facilitator is to listen and observe - how fast new stickies are appearing, where discussion is taking place (try to capture events people are arguing about). Encourage the team to try to identify as many events as possible. If somebody is wrong, it’s okay and others will correct.
When someone is mentioning some mysterious term, capture its definition. As a facilitator you can and you should ask obvious questions as it takes the burden off the other participants.
This is also a phase where divergent thinking takes place as a part of chaotic exploration. So on the board we have a lot of events (ideas). Some of them are better and some are worse but we do not judge them at this point — later we will see where they lead us. Once again you should encourage the participants to generate new ideas and set aside critical thinking and judgement.
Tips: As an icebreaker you can place the first event or events - to show how easy it is, and help draw participants into workshops.
Try to eliminate actors from the events - because we don’t want to impose mental boundaries as we may not notice that there is some other case. For example instead of
Buyer added item to cartuse
Item added to cart.
How to manage people
Sometimes it is a good idea to divide them into smaller groups and make them work together on the same issue or, quite the opposite, to focus on different areas of the system.
Depending on whether we are exploring or modelling the process, especially during online sessions, I think it is good to have boundaries — like a start event and an end event — among which everybody can create their vision. Then the most difficult part is to merge it. Another approach is to give a free hand to your participants and see how the process is going to develop.
How long should it take?
When the speed of new events showing up dramatically slows down, it is a good time to proceed to the next phase. Usually chaotic exploration takes about 5 to 15 minutes, but I have noticed that after about 8 minutes people are getting bored and busy with other things. So especially during online meetings, when you do not control the environment (like computers, phones, chat, mails…) it is easy to lose attention. And if you add to it a zoom fatigue syndrome, you can spoil the whole session when key participants leave.
Phase 2 Timeline
After the divergent step, now it is the time for the emergent phase where we want to explore and experiment - this is what we will be doing during the next phases.
What is happening
Now our goal is to make sure we are actually following the timeline - we would like the flow of events to be consistent from the beginning to the end.
Your role as a facilitator:
A lot of events are going to change their place, also participants will find them irrelevant or duplicated and that is okay. Remove the duplicates, but be careful — ask if those duplicated events mean the same thing for everybody! Do not hesitate to add, remove or change some sticky notes on the board.
At this step some issue points may appear, so it is good to mark them as hotspots. Use red sticky notes and write the issue down but this is not a good time to deliberate about it now. Try to postpone this discussion until we have structured the whole process.
Tip: During the online session when everybody is working solo, it is hard to merge all events and, including attention problems, you may be left alone. So my solution is to introduce the next phase right now.
Depending on the team - you can pick some random person who is going to start creating a timeline based on available events. To sustain attention, replace this person with another one. In case of inconsistencies with the timeline, we complete it with the missing events.
However, you can do all of it — if among participants there are some shy people or your participants’ supervisor is in the room, when you tell the story you can make intentional errors or ask silly questions. All of this eventually will help to explore the domain.
Because as a facilitator you do not have to know everything — especially the domain or business your participants are exploring — you help them effectively and safely discover processes, find new solutions or define problems.
Phase 3 Explicit walk-through and reverse narrative
What is happening:
Next step is to do a walk-through by creating some sort of a story that can be told based on the events placed on the board. During this step a lot of discussions (arguments) are going to take place. Maybe some events are missing, so do not hesitate to add, remove or change some sticky notes on the board. We should focus on the happy path in the first place.
1. Explicit walk-through
Your role as a facilitator:
Pick some random person who is going to start telling a story based on available events according to timeflow (from left to right). Sometimes the team gets blocked. In this situation you can add or move an event and place it in an obviously wrong place. Your error will be fixed quickly and help the team to move on.
How to help the participants discover more?
The answer is simple — by asking questions. There are some useful questions that you can ask when discussing almost every event, e.g.:
- Why did this event happen?
- What are the consequences of this event?
- What has to / needs to happen next?
Going deeper (of course that depends on how deep you want to go)
- What, how, when, why is it changing?
- When it can’t change?
- How does this affect the business?
Tip: Also in this phase it can be convenient to introduce actors (phase 4 - people and systems) — if it helps to tell a story or better understand the process do not hesitate (remember I told you that EventStorming is a tool?)
2. Reverse narrative
Your role as a facilitator:
Sometimes it is good to propose a reverse narrative / reverse chronology. Pick an event from the end of the flow and look for the event that made it possible - it must be consistent - no magic gaps between events. Again if we miss some events - add them.
Some questions you can ask:
- What has happened before X
- What else has to happen for X to happen
- Between - we take two corresponding events
- Is there anything else happening between X and Y
- Alternative - ask about alternative events
- What if X did not happen
- What if 10% of X happened or 150% of X happened
Phase 4 People and systems
What is happening
When we finish enforcing the timeline and we have a consistent flow of our business we can add people and external systems. We need them for clarity and better understanding of events and forces governing our business.
For marking people we use a yellow sticky note with a symbolic drawing of a person or clock if we want to show that time matters. External systems may be represented by large pink stickies with their names on it. By an external system I mean a piece of the whole process which is beyond our control e.g. an application, a department, other companies.
Who is an actor?
In his book Alberto Brandolini explains that
The goal is not to match the right yellow sticky note to every event in the flow. Adding significant people adds more clarity, but the goal is to trigger some insightful conversation: wherever the behaviour depends on a different type of user, wherever special actions need to be taken, and so on.
The lack of precision is helping in discussion and exploration. It can be a specific person for example:
- in our business model only Mrs. Smith can issue an invoice.
- or after some time reservation is cancelled so even time can be an actor.
- order cancellation can have two actors: client and CEX worker.
Phase 5 Opportunities and risks
In this phase we can literally take three steps back and look at the whole business flow as it is. Hot spots are the most conspicuous things - and it is easy to say where the biggest impediment is. This is a great occasion for additional discussion and a subject for further exploration.
Tip: Remember that each hot spot should be addressed and resolved before the next session takes place.
Another way to find where problems might lay is voting for a specific event or marking events that indicate where in our flow we are generating / losing money or value. For example by green stripes we indicate events where we are earning money, by red stripes where we are losing money or value.
It is like Pizzas
When all hotspots are addressed, you have found the biggest impediment, or you know on what part you have to focus on during next session. The only thing left to do is to close the workshop, thank all stakeholders and participants, schedule the next session and ask for feedback.
After the session you will have a clear business narrative on the board. What is more important, participants will share general understanding of the process. They have gone through the massive learning process, gained experience and shared the common knowledge — everybody uses the domain language. Due to the fact that we used simple building blocks, the outcome is understandable to everyone PMs, UX designers, developers etc.
The steps described above and their sequence should be regarded as optional during the session. There is no such thing as one recipe. For example, if during the timeline step you feel that introduction of people and systems is going to help, do not hesitate to do so. In other cases you will be interested only in finding impediments or where your system is delivering values and do not feel obligated to use all the steps. As Alberto says:
I like to think about it like Pizzas: there’s a common base, but different toppings.
Nobody is excluded
Big Picture EventStorming is the first and crucial step, its outcome is visible and valuable. Depending on what the team needs, it can be sufficient, but if we want to go deeper and explore more, next there are Process Level and Design Level EventStorming. We use the same stickies’ grammar enhanced with more colours to explain the complexity of our system. Due to the fact that we use the same grammar, developers and businesses can speak the same language — nobody is excluded, isn’t that great?
Those further steps (Process/Design Level) are getting us closer into the domain-driven-design and implementation. We ( developers/architects) can start thinking how to change what we have learned into working code, because
(…) it’s developer understanding that gets captured in code and released in production.
Call for action
If you are Allegro worker and you are interested in EventStorming, you want to develop, participate in workshops or help as a facilitator I strongly encourage you to join the guild. If you are not yet working at Allegro but are interested in how we use EventStorming maybe it is good opportunity to join us — #goodtobehere.
More about EventStroming
On the Internet you can find a lot of materials about EventStorming. Below is a list of those I found most valuable.
- Introducing EventStorming Alberto Brandolini’s book — EventStorming Bible — mandatory book!
- The EventStorming Handbook by Paul Rayner — a great summary of Introducing EventStorming with a lot of valuable tips, tricks and recipes. After that you will be able to explain EventStorming even to your own child.
- GameStorming A Playbook for Innovators, Rulebreakers, and Changemakers by Dave Gray, Sunni Brown, James Macanufo — if you want to use the full potential of your storming sessions.
- Facilitator’s Guide to Participatory Decision-making by Sam Kaner, Lenny Lind — how to be a better facilitator, not only for EventStorming. You will find precious information about divergent, emergent and convergent thinking and why it is important.
- Awesome EventStorming by Mariusz Gil — I belive this is the biggest source of links about EventStorming topics.
I would like to thank all of my colleagues from Allegro EventStorming Guild for their help in creating this article.