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Split an activation

Splitting an activation will result in two message calls that each do part of the work done by the original call. Both will return the result of the original message, so you will probably want to edit one of them.

The goal of splitting an activation is to distribute its responsibilities over separate messages so that the parts can be manipulated individually.

For example, when we split the call in the diagram below at the indicated position :

UML sequence diagram before a simple message split

Everything the call did will be divided over two messages with the same label and result :

UML sequence diagram after a simple message split

Splitting a message also takes into account any relevant combined fragments. For example,

UML sequence diagram before a complex message split

The two resulting calls will contain the same kind of combined fragment as the original did :

UML sequence diagram after a complex message split

You can only split a message using the mouse and when in diagram edit mode.

With the mouse

  1. Select the activation of the message call you want to split
  2. RIGHT-CLICK at the location where you want to split the activation, the message context menu will open.
  3. Select the 'Split here' menu item

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