Objects that are input to, or output by, an action can be shown as object symbols on the Activity diagram. To display this, a dashed arrow is drawn from an action to an output object, and a dashed arrow is drawn from an input object to an action state.
Frequently, the same object is manipulated by a number of successive activities. To show this, the object is drawn multiple times on the diagram, each appearance denoting a different point during its life.
Object state symbol
To draw an Object in State, use the Object State symbol. The Object State symbol represents the state of the object during the workflow. Therefore the name of the Object State symbol should be the name of the state that the object is in.
The Object State symbol contains three parts: the dashed flow line that enters the object in state, the object in state symbol itself, and the dashed flow line that exits the object in state.
When drawn, the Object State symbol can be defined by the class and the object (instance of class) that the Object State represents. As soon as an object is entered into the Action State's definition, the name of the object is displayed as the name of the symbol on the diagram, and the Object State name is placed in brackets.
Example
Perform the following steps to create the diagram below.
1 Create an object named Order (for example, right‑click Definition in the browser and select Object from the drop-down list).
2 Draw the Action states Request service, Pay, Take order, Fill order, and Deliver order.
3 Draw Action Transitions between Request service and Pay.
4 Draw an Object State symbol between Request service and Take order. The Object State is displayed as a three-part structure – a dashed input flow line, an Object in State rectangle, and a dashed output line. Name the Object State placed.
5 Open the definition of the Object State symbol and add a class named Order to the Class property list box. Click Choices and drag in the object named Order. Click OK to close the dialog.
6 Using the Object State symbol, draw an Object in State flow between Take order and Fill order, and name it entered. In the Object State definition, add the class Order and the object Order, as described in step 5 above.
7 Using the Object State symbol, draw an Object in State flow between Fill order and Deliver order, and name it filled. In the Object State definition, add the class Order and the object Order, as described in step 5 above.
