4. Activity Diagram Toolbar Selection Tool Note State Start State State Transition Horizontal Synchronization Decision Text Box Anchor Note to Item Activity End State Transition to Self Vertical Synchronization Swimlane
To create an activity diagram in the Browser Click right to select the “owning” package or use case in the Browser and make the popup menu visible. Select the New:Activity Diagram menu command. While the diagram is still selected, enter the name of the diagram. To open an activity diagram Double click on the activity diagram in the browser. An activity diagram is used to model the workflow of a business process, an operation of a class or a use case flow of events (see RUP). It can be added to a package or a class. For simplicity, this course uses an activity diagram to describe the Create a Schedule scenario in the Register for Courses use case. Note that the main difference between an activity diagram and a statechart is that activity diagrams are activity centered; statecharts are state centered.
To customize the activity diagram toolbar Click right on the toolbar to make the popup menu visible. Select the Customize menu command. Click to select the button that you want to add or remove. Click the Add or Remove button to add or remove the button from the toolbar. Click the Close button to close the Customize Toolbar window.
To create an activity Click to select the Activity icon on the toolbar. Click on the activity diagram to place the activity. While the activity is still selected, enter its name. An activity represents the performance of a task in a workflow. It is similar to a state, but with no significant waiting (for events).
To create a state transition Click to select the State Transition icon on the toolbar. Click on the originating activity. Drag the state transition arrow to the successor activity. In an activity diagram, a state transition shows the path from one activity to the next. When one action completes, flow of control passes immediately to the next action.
To create a reflexive transition Click to select the Transition to Self icon on the toolbar. Click on the state. A reflexive state transition is when the successor activity is also the origination activity.
To create a start state Click to select the Start State icon on the toolbar. Click on the diagram to place the start state. Click to select the State Transition icon on the toolbar. Click on the start state on the diagram and drag the arrow to the successor activity. The start state is the initial state of an activity. There is only one start state.
To create a fork Click to select the Horizontal Synchronization icon on the toolbar. Click on the diagram to place the fork. Click to select the State Transition icon on the toolbar. Click on the originating activity on the diagram and drag the arrow to the fork. Click to select the Activity icon on the toolbar, and place the activity on the diagram. Repeat for each concurrent activity. Click to select the State Transition icon on the toolbar. Click on the fork, and drag the arrow to the destination activity. A fork represents splitting a single flow of control into two or more concurrent flows of control. A fork can also be drawn with a Vertical Synchronization.
To create a join Click to select the Horizontal Synchronization icon on the toolbar. Click on the diagram to place the join. Click to select the State Transition icon on the toolbar. Click on the originating activity on the diagram and drag the arrow to the join. Repeat this for each concurrent activity. A join represents the synchronization of two or more concurrent flows of control. A join can also be drawn with a Vertical Synchronization.
To create a decision Click on the Decision icon on the toolbar. Click on the diagram to place the decision. Click to select the State Transition icon on the toolbar. Click on the originating activity and drag the arrow to the decision. A decision is when the workflow branches based on guard conditions. If the decision has two outgoing transitions, the transitions should be determined by a boolean expression.
To create a guard condition Add a new activity to the diagram. Click to select the State Transition icon on the toolbar. Click on the decision on the diagram and drag the arrow to the new activity. Click right on the transition to make the popup menu appear. Select the Open Specification menu command. In the Specification dialog, select the Detail tab. Enter the guard condition in the Guard Condition edit control. Click OK to save the guard condition. The guard condition should be a boolean condition. The guard condition is evaluated only if the flow enters the branch.
To create a swimlane Click to select the Swimlane icon on the toolbar. Click on the activity diagram to place the swimlane. Swimlanes represent organizational roles or units in a business model or specific classes in the design model.
To assign a class to a swimlane Right mouse click on the swimlane title bar in the activity diagram to make the popup menu visible. Select the Open Specification menu command. Click on the Class dropdown list box to select a class. Select a class from the dropdown list box. Click OK to save your work. Assigning a class to a swimlane means that the class is responsible for the activity placed in that swimlane. You can also specify organizational units or business roles for a business model. In this case, the user names the swimlane and does not assign a specific class to the activities.
To move an activity to a swimlane Click to select the activity to be moved. Drag the activity to the appropriate swimlane.
To create an end state Click to select the End State icon on the toolbar. Click on the diagram to place the end state. Click to select the State Transition icon on the toolbar. Click on the originating activity on the diagram and drag the arrow to the end state. An end state is the final state of an activity diagram. An activity diagram can have multiple or no end states.
This is the activity diagram for the Create a Schedule scenario of the Register for Courses use case.
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