An Activity is a parameterized Behavior represented as a coordinated flow of Actions. An Activity specifies the coordination of executions of subordinate behaviors, using a control and data flow model. The subordinate behaviors coordinated by these models may be initiated because other behaviors in the model finish executing, objects and data become available, or events occur external to the flow. The flow of execution is modeled as activity nodes connected by activity edges. An Activity element is created in the Activity diagram. 
An Activity can be specified by changing its property values in the Activity Specification window. Each property is described in the description area on this window.
General specification pane properties | Property Name | Function |
|---|
Read Only | If true, this activity must not make any changes to variables outside the activity or to objects. (This is an assertion, not an executable property. It may be used by an execution engine to optimize model execution. If the assertion is violated by the action, then the model is not formed correctly.) The default is false (an activity may make non-local changes). | Single Execution | If true, all invocations of the activity are handled by the same execution. | Node | Nodes coordinated by the activity. |
In the Activity Specification window, choose Variables from the property group list. | 