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Short note: Swimlanes

Short answer

Swimlanes are partitions in UML activity diagrams that divide the workflow into lanes representing actors, departments, or roles. They show who performs each activity and the handover of work between parties. Lanes are separated by lines with names at top; activities placed in responsible lane, arrows cross lanes when work moves. They clarify responsibility, reveal bottlenecks, and aid business process modeling.

Write a short note on Swimlanes.

Swimlanes (partitions) are a feature of the UML activity diagram. They divide the diagram into parallel vertical (or horizontal) lanes, each lane representing a person, department, role, class or system that is responsible for the activities placed in it.

Purpose

  • Show who does what in a workflow.
  • Show the hand-over of work between actors or organisational units.
  • Combine the flow of control with responsibility, so a business process becomes easy to read.

Notation

Lanes are separated by vertical lines; the lane name is at the top. Activities (rounded boxes) are placed in the lane of the responsible party, and arrows cross lanes when the work moves from one party to another.

 |  Customer  |   Clerk    |  Warehouse |
 |------------|------------|------------|
 |  (start)   |            |            |
 |    v       |            |            |
 | [Place     |            |            |
 |  order] ---|-> [Verify  |            |
 |            |   order] --|-> [Ship    |
 |            |            |   goods]   |
 | [Receive <-|------------|--- /       |
 |  goods]    |            |            |
 |  (end)     |            |            |

Advantages

Responsibility is clear, bottlenecks and unnecessary hand-offs show up, and the diagram is useful for business process modelling and for assigning activities to classes or departments.

✓ Answer checked by Claude Opus 5.5 (high effort)

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