Event storming
Alberto Brandolini's event-storming board in its canonical colours: orange domain events on a timeline, blue commands, yellow actors, purple policies, pink external systems, green read models and lilac aggregates — with hotspots called out in red. Swimlanes group by bounded context, and the engine flags the shapes DDD says are suspect: an event no command produces, a command with no aggregate, an aggregate with no events.
In the same space
Most users come to Event storming from Miro event storming boards, EventStorming.com kits or Whiteboard photos. flowss runs this engine in the browser — no install, shareable via URL, exportable to PNG / SVG / PDF / source.
Syntax at a glance
context "Retailing"
actor Passenger
aggregate Basket
command "Buy ticket" by Passenger on Basket emits "Ticket purchased"
event "Ticket purchased"
hotspot "Split ticketing?"Paste this in the Studio code pane to see Event storming render live. The full grammar is at the upstream-docs link above.
Sample templates
All 13 →Retail order fulfilment across ordering, warehouse and delivery contexts, with two cross-context policies and an uncommanded delivery event the storm leaves on the wall.
Reservation, payment authorisation and front desk for a hotel group, surfacing a search command that changes nothing and an authorisation expiry no command produces.
First notification of loss through assessment to settlement, showing a single validation command that fans out into an accept and a decline event.
Emergency department arrival through bed management to the ward, with the discharge event nobody commands and two hotspots concentrated on the bed-request boundary.
Trial, invoicing and dunning for a SaaS product: four policies chain the contexts together and a failed payment routes into collections.
Rider request, dispatch matching, trip and fare across four bounded contexts, with a driver cancellation event the model never causes.
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