You notice the Ticket object changes state as it moves through this activity diagram. When the Ticket Agent performs the Generate Pass activity, the Ticket object has the valid state. After the Boarding Agent performs the Stamp Pass activity the Ticket changes to the used state.

 Tip   Use a connector when you run out of space in an activity diagram. For example, we ran out of room at the Receive Pass activity that the passenger performs. So, we placed a connector with the label A. Then we drew a control-flow line from Receive Pass to the A connector. Using the same technique, you can pick up the control-flow path at the connector with the same label A at the top of the Passenger’s swim lane, and then proceed to the Wait in line activity.

The Five Steps are as follows:

1. Define. Identify the requirements of your system via Use Case Diagrams. Add other diagrams where they shed light on the use cases.

2. Refine. Detail the steps in each requirement via scenarios captured in Activity Diagrams. Add other diagrams where they shed light on the activities.

3. Assign. Use the Activity Diagrams to assign the steps to elements of your system.

4. Design. Show the relations among the elements with Component Diagrams. Add other diagrams where they shed light on the components.

5. Repeat/iterate/drill down/divide and conquer. Narrow the scope of your process to individual elements (designed with Class Diagrams); or expand it out to whole systems (designed with Deployment Diagrams). Add other diagrams wherever they help you understand the system. Repeat Steps 1 through 4 as appropriate for the current scope. Like Boehm's Spiral development process, Evolutionary Development, and many other modern processes, Five-Step UML is an incremental, recursive approach.