At the end of the previous article in the Process Mapping Fundamentals series, I mentioned that I'd written the processes from two different perspectives. Swimlanes allow you to display who does what in a simple and easy-to-understand way, allowing you to combine the activities of several people and roles into one diagram.

Swimlanes

The swimlanes are usually horizontal rectangles running along the length of a landscape page with an additional box on the left-hand side for the role title. In this example, I've put credit-checker in the top lane and supervisor in the bottom lane. They can be vertical with the page in portrait orientation. That's rarer and may depend on the modelling notation being used. For instance, I've seen more UML Activity Diagrams in portrait than landscape. Sometimes it's simply a matter of which way fits on the page better.

We do not need one swimlane per person unless each is performing a different role. So this isn't about Dave does x or Sam does y, it's about the role that Dave plays and the role that Sam plays.

Roles

Part of process analysis is figuring out the different roles involved in the process. We're concerned with the difference in roles, not the fact that they're different people. Coming from a UML background, I often use the word actor instead of role. I find them generally interchangeable at this level.

For instance, if a process involves 10 people, 7 of them may perform the same process steps, so we could roll them up into one role. 2 of them may be supervisors, e.g. one supervisor for day shift, one for night. The other person could be a manager. That results in 3 roles. Since the roles are always by different people, we'll have 3 actors.

Add the process tasks

I've used the swimlanes from earlier and we still have 3 actors in the process. One for each of:

• Credit-checker
• Supervisor
• Manager

Now that we've made the swimlanes, we can put the process tasks in. Think of swimmers in their swimlanes in the competition pools, only one swimmer per lane and they're the only one allowed in their lane. It's similar for swimlanes with processes. The rule is one swimlane per role. The only process steps you can put in a swimlane are those performed by that role. If the step is performed by another role, then it should be in a different swimlane.

As one role performs a process step and passes the output of that step onto the next stage (often a different role), then the connector will cross the swim-lane boundary between the two boundaries.

Summary

To recap, Swimlanes:

• can be horizontal or vertical
• act as a boundary for a task
• are associated with roles and the tasks they perform
• enable us to differentiate between the tasks performed by different roles
• are about the role, not the person

Next

We'll discuss messages and then the difference between sequential and parallel processing.