Working with an Object Flow or a Control Flow - UML 2.0

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You can create control flow or object flow as an ordinary link between the two node elements. The valid nodes are highlighted when the link is established.

You can scroll to the target element if it is out of direct reach, or you can use the context menu command to avoid scrolling.

There are certain limitations stipulated by UML 2.0 specifications:

  • Object flow link must have an object at least on one of its ends.
  • It is impossible to connect two actions with an object flow except through an output pin on the source action.
  • Control flow link may not connect objects and/or activity parameters.

Use the following techniques with an object flow or a control flow:

  1. Create a flow
  2. Create a fork or a join
  3. Create a decision or a merge

To create a flow:

  1. Right-click the source element of the flow.
  2. On the context menu, choose Add > Control Flow or Add > Object Flow . The Choose Destination dialog box opens.
  3. In the Choose Destination dialog box, select the target and click OK. Note that the OK button is only enabled when the valid target is selected.

To create a fork or a join:

  1. Identify the actions involved. If necessary, place all of the actions on the diagram first. Lay them out as desired.
  2. Place either a fork or a join on the diagram. Resize as needed.
  3. If depicting multiple sources, draw control flow from each of the source actions to the join, and from the join to the target action. If depicting multiple targets, draw control flow from the source action to the fork, and from the fork to each of the target actions.

To create a decision or a merge:

  1. Identify the actions involved. If necessary, place all of the actions on the diagram first. Lay them out as desired.
  2. Place either a decision or a merge on the diagram. Resize as needed.
  3. If merging multiple actions, draw control flow from each of the source actions to the merge, and from the merge to the target action. If making a decision, draw control flow from the source action to the decision, and from the decision to each of the target actions.

See Also