Object Flows are used in Activity diagrams and State Machine diagrams. When used in an Activity diagram, an Object Flow connects two elements, with specific data passing through it. To view sample Activity diagrams using Object Flows, see the Using Object Flows in Activity Diagrams topic
In State Machine diagrams, an Object Flow is a specification of a state flow or transition. It implies the passing of an object instance between elements at run-time.
You can insert an Object Flow from the State or Activity pages of the Enterprise Architect UML Toolbox, or from the drop-down list of all relationships located in the header toolbar. You can also modify a transition connection to an Object Flow by selecting the ObjectFlow checkbox on the connection Properties dialog.
See Control Flow for information on setting up Guards and Weights on Object Flows.
OMG UML Specification
The OMG UML specification (UML Superstructure Specification, v2.0, p. 12) states:
"A state in an activity diagram that represents the passing of an object from the output of actions in one state to the input of actions in another state."
The OMG UML specification (UML Superstructure Specification, v2.0, p. 344) states:
"An object flow is an activity edge that can have objects or data passing along it."