Structured Activity


Structured Activity elements are used in Activity diagrams. A Structured Activity is an activity node that can have subordinate nodes as an independent Activity Group. You can set an option to ensure that no other Activities or their side effects interfere with this Activity's processing (the Must Isolate checkbox in the Structured Activity element Properties dialog).

Enterprise Architect provides a number of  forms of Structured Activity, both basic and specialized, for creating composite Activity elements quickly and simply.

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See Also

Create Structured Activities

When you drag a Structured Activity icon from the Toolbox onto a diagram, a short menu displays from which you select one of the following options:

Loop Node
Conditional Node

The first two options specifically create a Loop Node or Conditional Node.

The Other option displays the New Structured Activity dialog, on which you can select to create one of the five following types of Structured Activity element.


Loop Node

Conditional Node

Simple Composite Activity

Provides a Composite Activity element with a child Activity diagram.


Composite Elements


Loop Node

Represents a sequence of Actions and Activities that are to be repeated within the object.


Loop Node

Conditional Node

Represents an arrangement of Actions and Activities where choice determines which Activities are performed.


Conditional Node

Structured Activity Node

Represents an ordered arrangement of executable Activity nodes (Actions, Decisions, Merges and so on) that can include branched and nested nodes; this is the base element from which the other types of Structured Activity are derived.


Structured Node

Sequential Node

Represents a sequential arrangement of executable Activity nodes.


Sequential Node

Nodes as Composite Elements

Loop Node and Conditional Node elements are composite elements, but the child element structures are created on the same diagram as the node element itself (in the same way as for a Composite State). Therefore:

The composite element symbol is not set
You cannot display a separate child diagram
The Show Composite Diagram facility is not available for these nodes

You could set these nodes as 'normal' composite elements and create and open a child diagram, but you should not use Loop or Conditional Nodes in this way.

The Show Composite Diagram facility is also not available on the Structured Activity Node, as this is the base element for the Loop and Conditional Nodes. You can, however:

Use the Sequential and Structured Activity nodes as composite elements, and
Display a child diagram structure on its parent Sequential node


Composite State


To protect the processing of a Loop or Conditional Node Structured Activity from interference from other Activities or their side effects, open the element's Properties dialog and select the Must Isolate checkbox on the Loop or Condition page

Toolbox icon


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