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Activity Parameter Nodes


An Activity Parameter Node accepts input to an Activity or provides output from an Activity.

This example depicts two entry parameters and one output parameter defined for the Activity.

A UML Activty Diagram example using Sparx Systems Enterprise Architect.

Define an Activity Parameter Node for an Activity

UML Activity Diagram example showing the use of an Parameter nodes on an Activity, in Sparx Systems Enterprise Architect.




Right-click on the element and select the 'New Element | Activity Parameter' option.


The 'Properties' dialog displays, which prompts for the name and other properties of the embedded element.


To further define the new Activity Parameter, select the 'Parameter' tab of the 'Properties' dialog and define:

  • Type
  • Default Value
  • Direction
  • Whether this is a fixed value
  • Multiplicity upper and lower bounds
  • Whether to allow duplicates and
  • Whether multiplicity is ordered

Activity Parameter Nodes also have the 'Exception' and 'Stream' options:

  • Exception indicates that a parameter can emit a value at the exclusion of other outputs, usually because of some error
  • Stream indicates whether or not a parameter can accept or post values during the execution of the Activity

Learn more

OMG UML Specification:

The OMG Unified Modeling Language specification, (v2.5.1, p.398) states:

As a kind of Behavior, an Activity may have Parameters (..). When the Activity is invoked, values may be passed into the Activity execution on input Parameters (i.e., those with direction in or inout) and values may be passed out of the Activity execution on output Parameters (i.e., those with direction inout, out or return).

Within an Activity, inputs to and outputs from an Activity are handled using ActivityParameterNodes. Each ActivityParameterNode is associated with one Parameter of the Activity that owns the node. The type of an ActivityParameterNode shall be the same as the type of its associated Parameter.