The whole room on one wall, in order.
Event storming works because the wall is wide and the order is visible. A room argues about what happens and in which sequence, and the disagreements show up as two events claiming the same moment — that is where the hotspot goes.
An aggregate opens its own board.
Order carries a green dot: under it is the board where its life is worked out on its own — every event that changes it, from placed to picked up, and the command that causes each one. The wall stays readable, and the detail has a place to go.
The colours are types, so the wall reads back.
A domain event is an object of its own type, and so is a command, a policy or an aggregate. After the workshop the wall is read back from the project page — what the aggregates were, which policy reacted to which event — instead of being photographed and retyped somewhere else.
| TYPE | OBJECTS | ON THE WALL |
|---|---|---|
| Domain Event | 6 | Order placed, Payment authorised, Ticket printed, Drink ready… |
| Command | 5 | Place order, Authorise payment, Mark ready, Hand over… |
| Policy | 1 | When paid, print a ticket |
| Aggregate | 1 | Order |
| External System | 2 | Payments provider, SoHo till |
| Read Model | 1 | Pickup shelf |
| Hotspot | 2 | Pay before or at pickup? · Two events at 8:15 |
Every figure, named.
The toolbar's own names — what you pick is what this list says: two groups, 16 figures.