Activity Diagrams

If you've ever taken an introductory course in programming, you've probably encountered the flowchart. The flowchart shows a sequence of steps, processes, decision points and branches. Novice programmers are encouraged to use flowcharts to conceptualize problems and derive solutions.

The UML activity diagram is much like the flowcharts of old. It shows steps (called, appropriately enough, activities) as well as decision points and branches. It's useful for showing what happens in a business process or an operation. You'll wind it an integral part of system analysis.

First and foremost, an activity diagram is designed to be a simplified look at what happens during an operation or a process. It's an extension of the state diagram. The state diagram shows the states of an object and represents activities as arrows connecting the states. The activity diagram highlight the activities.

Each activity is represented by a rounded rectangle - narrower and more oval-shaped than the state icon. The processing within an activity goes to completion and then an automatic transmission to the next activity occurs. An arrow represents the transition from one activity to the next. Also an activity diagram has a strating point represented by filled-in circle, and endpoint represented by a bull's eye.

Transition from one activity to another in the Activity Diagram

In next lesson will be explained ways of creating an activity diagram, rules between activities, and at the end an example for this diagram will be given to you.

The activity diagram is an extension of the state diagram. State diagrams highlight states and represent activities as arrows between states. Activity diagrams put the spotlight on the activities. Each activity is represented as a rounded rectangle, more oval in appearance than the state icon. The activity diagram uses the same symbols as the state diagram for the startpoint and the endpoint.