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UML Activity Partition element displayed as a horizontal swimlane.


Enterprise Architect supports two types of Activity Partition:

  • The Activity Partition feature, which is used to logically organize an Activity element
  • The Activity Partition element, described in this topic, which is used to logically organize an Activity diagram

These have similar effects - they partition the Actions of the Activity without affecting the token flow, helping to structure the view or parts of the Activity.

This example depicts the partitioning between the Classes Process Payment and Order Processor.

UML Activity Diagram example, demonstrating use of partitions, in Sparx Systems Enterprise Architect.

The Partition orientation defaults to horizontal. To turn it into a vertical Partition, right-click on it and select the 'Advanced | Vertical Partition' option.

You can neatly align and join the Activity Partitions on a diagram using the element context menu 'Dockable' option. For Partitions, the option defaults to selected.

Setting Opaque Fill

Whilst an Activity Partition usually contains a number of other elements, there might be reasons for hiding those elements as well as times to fully show them, or perhaps just indicate that they are there, depending on the immediate purpose of the diagram. You can apply these nuances in the display of the Partition contents by changing the opacity of the element's fill color.

Before setting the opacity, give the element a fill color.

You set the opacity using an icon from either of these two pop-up element toolbars:

  • Click on the Activity Partition element and on the icon:
  • Right-click on the Activity Partition element and look above the context menu:

Click on the icon and select:

  • 100% for total opacity, where the contents of the Activity Partition are hidden (you can first right-click on individual elements and select the 'Z-Order | Bring to Top' option to expose those elements only)
  • 0% for no opacity, where the fill color is not applied and the Activity Partition contents are fully visible
  • 75%, 50% or 25% to set the appropriate degree of opacity and make the content elements visible but over-shaded

Toolbox icon

Partition element

Learn more

OMG UML Specification:

The OMG UML specification (UML Superstructure Specification, v2.1.1, p.341) states:

Partitions divide the nodes and edges to constrain and show a view of the contained nodes. Partitions can share contents. They often correspond to organizational units in a business model. They may be used to allocate characteristics or resources among the nodes of an activity.

The OMG UML specification (UML Superstructure Specification, v2.1.1, p.341) also states:

An activity partition is a kind of activity group for identifying actions that have some characteristic in common.