Pool
A Pool represents a participant in a collaboration — an organization, department, system, or role that owns a complete process. Pools act as containers for process flows and define boundaries for sequence flows, which cannot cross pool borders. For example, in an e-commerce order process, the Customer, the Online Store, and the Warehouse each get their own pool to show how they interact via messages. For example, in an order fulfillment collaboration, the "Customer" pool sends an order message to the "Retailer" pool, and the "Retailer" pool sends a shipping notification to the "Logistics" pool.
What is a Pool?
A Pool represents a participant in a business collaboration. It contains the process for that participant and acts as a boundary-sequence flows cannot cross between pools. When multiple organizations or systems interact, each gets its own pool, and they communicate via Message Flows.
Visual Representation
A Pool is shown as a large horizontal rectangle with a name label on the left side (or top). The entire process for that participant is contained within the pool's boundaries. Pools can be expanded (showing internal process) or collapsed (black box).
Key Characteristics
- Process container: All activities for a participant are placed inside their pool
- Boundary enforcement: Sequence flows stay within pools; only Message Flows cross between pools
- Naming: Represents the participant name (e.g., "Customer", "Sales Department", "Payment System")
- Collaboration modeling: Multiple pools show how different parties interact in a business scenario
Common mistake
Creating separate pools for departments within the same organization. Pools represent separate participants (organizations, systems). Use lanes within one pool for departments/roles.
How it connects
Common Use Cases
Cross-Organization Processes
Model interactions between your company and external parties-customers, suppliers, or partners-where each party has their own pool.
System Integration Views
Show how different systems communicate-e.g., an ERP pool exchanging messages with a CRM pool through APIs.
Departmental Handoffs
Visualize handoffs between departments that operate independently-Sales sends an order to Fulfillment via message flow between pools.
Frequently Asked Questions
Related BPMN Elements
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