Pools, Lanes, and Message Flows

Participants

Participants are responsible for performing the activities that comprise a process flow. Participants can be

• Organizations
• Roles
• Systems

Pools

Pools are containers for the sequence flow that a participant is responsible for.

• Every participant has their own pool.
• Every end-to-end process is contained within a single pool. In other words, sequence flows cannot cross pool boundaries.

“Black box” pools—such as the Customer pool below—are used when details of a participant’s process are unavailable or unimportant.

Lanes

Pools can be subdivided hierarchically to clarify responsibility for process activities.

In the example above,

• The Enterprise pool is divided into Sales and Operations lanes.
• The Operations lane is subdivided into Warehouse and Delivery lanes.

Message Flows

Message flows define how information flows between pools.

Message flow can connect flow objects in different pools, a pool and a flow object in a different pool, or two pools.

Incoming message flows must be received before an activity starts. Outgoing message flows are sent upon the completion of an activity. In the example above,

• Message 1 must be received before Task A can begin.
• Message 2 is sent immediately upon the completion of Task C.

Initiating Processes with Messages

Processes are often started upon the receipt of a message. In the following example, a customer order triggers Company’s order fulfillment process.