BPMN and swimlanes

The bpmn header models a business process. Groups become horizontal swimlane bands (one per participant or responsibility) and nodes rank across the lanes in flow order, so an edge that crosses a band reads as a handoff from one role to another.

bpmn
group Customer { Place order, Confirm receipt }
group Warehouse { Pick items, Ship }

Place order -> Pick items
Pick items -> Ship
Ship -> Confirm receipt

Two lanes; the edges between them are the handoffs.

Activities, events, and gateways#

BPMN has three core node roles, and each has an alias that draws the right shape:

Role alias	Draws	Means
`activity`	rectangle	a task someone performs
`event`	ellipse	something that happens (start, end, message)
`gateway`	diamond	a branch or merge in the flow

bpmn
group Applicant {
  Start [event]
  Submit form [activity]
}
group Reviewer {
  Review [activity]
  Complete [decision]
  Approved [event]
  Rejected [event]
}

Start -> Submit form -> Review
Review -> Complete
Complete -> Approved: pass
Complete -> Rejected: fail

event, activity, and a decision gateway across two lanes.

Lanes are groups#

A swimlane is just a group under the bpmn header, so everything you know about groups applies: a node can join a lane from its own declaration with [group: Name], and members can be declared inline or elsewhere. Nodes that belong to no lane fall into a trailing band.

bpmn

group Sales {
  Lead [event]
  Qualify [activity]
}
group Finance {
  Invoice [activity]
  Payment [event]
}

Lead -> Qualify
Qualify -> Invoice: won
Invoice -> Payment

An order-to-cash process across three responsibilities, with a decision gateway and a rejection loop.

bpmn
title: Order to cash

group Customer {
  Places order [event]
  Receives goods [event]
}
group Sales {
  Validate order [activity]
  Credit ok [decision]
  Approve [activity]
}
group Fulfilment {
  Pick and pack [activity]
  Dispatch [activity]
}

Places order -> Validate order
Validate order -> Credit ok
Credit ok -> Approve: yes
Credit ok -> Places order: no, revise
Approve -> Pick and pack -> Dispatch
Dispatch -> Receives goods