Collapsed Pool
A Collapsed Pool (Black Box Pool) represents an external participant without showing internal process details. It indicates interaction with an outside party whose internal workings are hidden or unknown.
What is a Collapsed Pool?
A Collapsed Pool represents an external participant as a black box. You interact with it through message flows, but its internal process is intentionally hidden-either unknown, out of scope, or simply not detailed.
Visual Representation
A Collapsed Pool displays as a horizontal rectangle without any internal activities-just the participant label. It is visually compact compared to expanded pools with lanes and activities.
Key Characteristics
- Black box view: Internal process is not shown
- External participant: Represents parties outside your organization or focus
- Message flow only: Interacts only via message flows, not sequence flows
- Scope management: Keeps diagrams focused on relevant process areas
Common Use Cases
External Customer
Show customer as a collapsed pool that sends orders and receives notifications without detailing customer actions.
Partner System
Represent a partner API as a collapsed pool that receives requests and sends responses.
Out-of-Scope Dept
Show another department as a black box when their internal process is beyond the current scope.
Frequently Asked Questions
Related BPMN Elements
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