In BPMN, swimlane is divided into types, pool and lane. A pool represents a participant who takes part in a process. It is a rectangular container that can contain flow objects vertically or horizontally, such as task and activity. On the other hand, a lane is a graphical sub-division in a pool. It is often used to organize and categorize activities within a pool according to function or role.
Pool and lane
A pool is usually used to represent a process in an organization, a lane, on the other hand, represents an activity of a department within that organization. By using pool and lane, you can identify how a process is done and which department performs that activity.
Defining black box pool
A pool can be shown either as a “white box” with all details exposed, or as a “black box” with all details hidden. When a pool presents as an empty box with no flow objects nor lanes, it is regarded as a “black box”. Since a black box pool merely represents a role, you can neither create flow objects in it, nor associate sequence flow with it, but you can attach message flows to its boundary.
Create a business process diagram beforehand. To create a pool, select either Horizontal Pool or Vertical Pool from diagram toolbar and click it on the business process diagram.
You can present an organization as a ‘black box’ pool in a business process diagram when the workflow of that organization isn’t the main concern in the issue or the workflow of that organization doesn’t relate to your process. That’s because drawing message flows to and from the black box pool can fully present the interaction between two organizations.
To define a black box pool, right click on an empty pool and select Black Box from the pop-up menu.
Creating nested lanes
Since a lane represents a sub-partition of a pool, it is possible to create lanes within a lane to form a hierarchical structure. These hierarchical lanes are called nested lanes.
In the following figure, you see the pool IT Consulting is divided into two lanes: Accounting and Customer Service, both representing departments within the same company. Customer Service can further be classified as two nested lanes named Hotline Support and On-site Support.
Create a pool in advance. To create a lane, select Lane from the diagram toolbar and click it inside the pool. Rename the pool as Account.
To create a nested lane, right click on a lane and select Add Child Lane from the pop-up menu.
On the other hand, you can make a lane to become a nested lane of an existing lane. Right click on a lane you want it to be nested lane, for example, Hotline Support and select a parent lane for it, for example, Customer Service. Select Set Parent Lane > Customer Support from the pop-up menu.
As a result, Hotline Support becomes a nested lane under Customer Service.