As discussed in Chapter 2, a swimlane is a visual region in an activity diagram that indicates the element that has responsibility for action states within the region. For example, the project management system may have the following swimlanes, which are illustrated in Figure 8-6:
Project Manager
Shows the action states that are the responsibility of a project
manager. The swimlane makes it obvious that the project manager is
responsible for entering data, thus the rather cumbersome action
state name of Project
Manager
Enters
Data
may be shortened to
Enter
Data
.
Project Management System
Shows the action states that are the responsibility of the project
management system. Again, because the swimlane makes it obvious who
(or what, in this case) is generating information, the rather
cumbersome action state name of Project
Management
System
Generates
Information
may be
shortened to Generate Information
.
Printer
Shows the action states that are the responsibility of a printer.
Because of this swimlane, the rather cumbersome action state name of
Printer
Prints
Information
may be shortened to
Print
Information
.
Notice how the use of swimlanes allows me to rename the action states to omit the responsible element for each action state.
In the UML, a swimlane is shown as a visual region separated from neighboring swimlanes by vertical solid lines on both sides and labeled at the top with the element responsible for action states within the swimlane. Figure 8-6 shows the swimlanes associated with the project management system.