Section 3.11. Partitions (or Swimlanes)

3.11. Partitions (or Swimlanes)

Activities may involve different participants, such as different groups or roles in an organization or system. The following scenarios require multiple participants to complete the activity (participant names are italicized):

An order processing activity

Requires the shipping department to ship the products and the accounts department to bill the customer.

A technical support process

Requires different levels of support, including 1st level Support, Advanced Support, and Product Engineering.

You use partitions to show which participant is responsible for which actions. Partitions divide the diagram into columns or rows (depending on the orientation of your activity diagram) and contain actions that are carried out by a responsible group. The columns or rows are sometimes referred to as swimlanes.

Figure 3-24 shows a technical support process involving three types of participants: 1st level Support, Advanced Support, and Product Engineering.

Figure 3-24. Partitions help organize this activity diagram by clarifying responsible parties

You can also show responsibility by using annotations. Notice that there are no swimlanes; instead, the name of the responsible party is put in parentheses in the node, shown in Figure 3-25. This notation typically makes your diagram more compact, but it shows the participants less clearly than swimlanes.

Figure 3-25. Annotations can be used instead of swimlanes as a way of showing responsibility directly in the action